How Do You Know Ductile Iron Is Fusion Bonded
Bandage iron and cast steel
Ramesh Singh , in Applied Welding Engineering (3rd Edition), 2020
Nodular (spheroidal graphite) cast iron
Nodular fe is as well called ductile iron. The graphite is present as tiny assurance or spheroids. Because the spheroids interrupt the matrix much less than graphite flakes, nodular cast fe has higher force and toughness than gray bandage iron. The formation of nodules or spheroids occurs when eutectic graphite separates from the molten iron during solidification. The separation of graphite in nodular grade is similar to separation of graphite in greyness cast atomic number 26 except that the additives facilitate the graphite to take nodular shape.
Spheroidal graphite (SG) cast iron has excellent toughness; it has higher elongation and is used widely, for example, in crankshafts. Unlike malleable fe, nodular iron is produced directly from the melt and does not require heat treatment. Magnesium or cerium is added to the ladle just before casting. The matrix can be either ferrite or pearlite or austenite. The quality of SG iron is excellent, and X-ray quality castings are regularly produced.
The latest quantum in cast irons is where the matrix of SG bandage iron is non pearlite but bainite. The chemical limerick of the SG cast iron is similar to that of the gray cast iron but with 0.05 wt% of magnesium. This results in a major improvement in toughness and strength. The bainite is obtained by isothermal transformation of the austenite at temperatures below which pearlite forms. The process of graphitization is discussed in some detail in the chapter on rut treatment.
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Selection and testing of metalworking fluids
R. Evans , in Metalworking Fluids (MWFs) for Cutting and Grinding, 2012
Ductile bandage fe
Ductile (nodular) iron has and continues to find wide use in the production of many industrial components. Ductile iron is similar to gray cast iron in composition, however during casting of ductile fe the graphite nucleates as spherical particles as opposed to flake-similar structures. The graphite construction is a primary reason for the higher strength and ductility exhibited by ductile irons and subsequently for their apply in the product of many industrial parts which include crankshafts, gears, rocker arms and disc brake calipers. With its higher forcefulness, the machinability of ductile iron tends to exist lower and the demands for lubrication provided by the fluid greater than that needed for gray cast iron. To attain the necessary level of lubrication, specific additives designed to provide friction reducing and anti-welding properties under more severe atmospheric condition of pressure and temperature can be utilized to enhance the machining of ductile irons. Such additives typically known as extreme pressure (EP) lubricants, function by reacting with the workpiece surface nether high temperature atmospheric condition, forming a low shear force organometallic or intermetallic motion picture, which serves to reduce friction and prevent metal-metal adhesion or localized welding betwixt the tool and the workpiece surfaces. Such additives have been shown to offer utility in more than severe ferrous metalworking operations. Three common classes of chemical types are known to effectively offer such backdrop, these beingness chlorinated hydrocarbons, organosulfur compounds and organophosphorus compounds.
Chlorinated paraffins have been used for many years as effective EP lubricants in metalworking fluids. Their utility has been demonstrated in the machining of ferrous metals equally well as in the machining of certain not-ferrous metals such as aluminum. 38–40 Although extensive studies have been conducted to elucidate the mechanism of the EP lubrication provided past chlorinated paraffins, at that place yet remains a degree of uncertainty with regard to the actual mechanism of activity. Even so, it is generally felt that at the elevated temperatures which are produced from the friction and/or deformation that occurs during the cutting procedure, the release of chlorides from the alkane with subsequent germination of a surface layer of metallic chlorides (Al or Fe) occurs, producing an constructive EP lubricating film. The chemical structures of two normally used chlorinated additives are shown in Fig. 2.21.
two.21. Chemical structures of common chlorine-containing lubricant additives.
Organosulfur compounds have also been long known to provide effective lubrication under EP conditions. 41–43 Such additives are believed to function by reacting with the metal surface, forming a lubricating picture comprising metal sulfides which offering effective friction-reducing and load-bearing properties. The formation of the lubricating metal sulfide flick is thought to go along via initial adsorption of a di or polysulfide moiety onto the workpiece surface, followed by rapid homolysis of the sulfur-sulfur bond, generating the metal sulfide layer (Fig. 2.22). The chemical structures of commonly used sulfur-based lubricant additives are shown in Fig. 2.23.
ii.22. Schematic of sulfur reactivity with metal surface.
2.23. Chemical structures of sulfur-containing lubricant additives.
Organophosphorus compounds are not by and large considered to be every bit constructive under EP lubrication conditions as chlorine- or sulfur-containing lubricants. All the same, depending on the structure of the compound, phosphorus-based additives are known to provide a degree of load bearing and anti-welding properties. 44–46 Many phosphorus-based additives used in today'southward metalworking fluids are full or partial phosphate esters prepared via the reaction of phosphoric acrid or anhydride with selected ethoxylated fat alcohols. Such additives tend to accept good surface active backdrop and under atmospheric condition of high temperatures during sliding in a metal-metallic contact, offer effective EP lubrication backdrop. Examples of commonly used phosphorus-based EP additives are shown in Fig. 2.24.
two.24. Chemical structures of phosphorus-containing lubricant additives.
While previous speculation near the structure and mechanism of lubricant movie formation with phosphorus-based additives involved the formation of a metal phosphate layer on the metallic surface, more than recent work conducted supports the formation of a more circuitous structure whereby the organic ligand on the phosphate plays a significant role in the formation and properties of a lubricating film comprising a viscous organometallic-organophosphate complex.
The use of effective EP lubricating additives tin offering notable benefits to the machining of ductile irons. Figure 2.25 shows the cutting forces measured for a water-based fluid used to machine form 65–45–12 ductile fe. The cutting forces measured for the fluid without the presence of EP lubricants, too as those measured for the same fluid containing effective levels of a chlorine, sulfur and phosphorus-based EP additive, are shown. The bear upon of the additives on the cutting forces is conspicuously seen. Consistent with the cutting forces measured, Fig. ii.26 shows microphotographs of the tool cut edges post-obit machining. While noticeable wear and chipping of the cutting border can exist seen with the additive-free fluid, the same fluid containing the various EP lubricants machines with much reduced clothing and devastation of the cutting edge.
2.25. Graph showing the impact of high force per unit area lubricants on axial cutting forces in 65–45–12 ductile atomic number 26 machining (1 lb = four.448 N; 1 lb-foot = 13.8 kg-cm).
2.26. Microphotographs of tool flank face following machining of 65–45–12 ductile cast atomic number 26. It shows college wear and noticeable chipping on the tool cut edge used with the fluid containing no extreme pressure level lubricating additive.
While the effectiveness of the EP additives in metalworking fluids can, and in nigh cases should, be assessed via machining tests prior to selection of the fluid, conventional benchtop lubrication testers tin can also exist useful for initial screening of the fluid and additive performance. Such testers include the Falex Pin on Vee Block Tester and the Beat Four Ball Tester. Both of these tribometers can be used to assess fluid performance under loftier pressure and temperature weather condition.
The do good of using EP-containing additives in water-based fluids tin also be seen in more severe ferrous machining operations such equally the gun drilling of ductile iron. Gun drilling is a metallic removal process involving a drilling machine, a high pressure coolant system and a high quality drill with a single or double flute along the shank. In a gun drilling operation, the drill is positioned and held in the spindle olfactory organ, then guided into the workpiece through a pre-started hole or guide bushing to forestall vibration and ensure accuracy. The drill tip'south cutting edges produce thin curled chips that are carried back along the shank by a loftier pressure menstruation of coolant. The off-centre pattern of the cutting edges creates pressure within the bore, which is carried by pads behind the drill tip.
The metalworking fluid used must sufficiently affluent out the chips and also lubricate the pads, which brighten the surface and develop the fine finish for which gun drilling is known. Thus the principal roles of the metalworking fluid in ductile iron gun drilling operations are to provide lubrication and cooling besides as to disperse and heighten chip removal effectively through the tool's flute. Every bit it is one of the more hard cutting operations, most fluids that perform well in a gun drilling operation will typically perform well in the remaining cutting operations. While diverse types of water-based and straight oil fluids have been used in deep hole drilling operations, the apply of a h2o-based macroemulsion type fluid containing a suitable EP additive is unremarkably the most effective. This is specially true when machining softer grades of ductile iron, such as course 65–45–12, which tends to soften and become more adhesive with increasing surface temperatures.
The use of EP additives can minimize heat generation during the drilling process and, equally a issue, limit localized welding also as more than catastrophic tool failure during the process. An example of this tin be seen in results obtained in the deep hole drilling of a grade 85–55–06 ductile iron using a unmarried fluted carbide drill and water-based emulsion type metalworking fluids. In assessing the inside angle flank clothing also as margin wearable and chipping which occur, it can be seen that the apply of an organophosphorus-based additive in the fluid finer reduces both flank face tool vesture equally well as wear and chipping of the drill margin (Fig. two.27 and two.28).
2.27. Within angle flank wear deep hole drilling of 85–55–06 ductile fe. The vesture expanse was measured and recorded in mmtwo. The article of clothing areas measured for the products tested are shown.
2.28. Metal adhesion on drill margin; deep pigsty drilling of ductile iron.
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Casting alloys and foundry data†
In Smithells Metals Reference Book (Eighth Edition), 2004
26.9.3 Compacted graphite irons
Although the existence of compacted graphite containing irons has been known for many years, it is but relatively recently that they have been commercially exploited. Such irons are characterised by the graphite being present in the form of relatively curt, thick flakes with rounded extremities and undulating surfaces.
In full general compacted graphite irons have mechanical and concrete backdrop intermediate between those of conventional chip graphite irons (grayness irons) and nodular graphite irons. The outstanding characteristics are skillful thermal conductivity combined with useful ductility and college tensile and fatigue strengths than for grey irons.
At nowadays no British Standard exists for these materials.
The presence of certain element combinations in irons which would otherwise solidify with a conventional flake graphite form may promote the formation of the compacted type of graphite. Now the production of compacted graphite irons is largely based on additions of magnesium and/or cerium to irons of depression sulphur content. The magnesium based treatments are similar to those employed for nodular graphite iron production while the cerium methods are usually simple ladle add-on processes.
In the magnesium procedure, equally the magnesium content is increased, the graphite construction changes from conventional flake, through compacted flake to fully nodular. The range of magnesium contents to facilitate compacted flake structures is very narrow and it is usually necessary to employ additions of titanium and cerium to extend the range and provide a practical ladle based process. Magnesium and titanium are unremarkably nowadays in the ranges 0.015–0.035 per cent and 0.08–0.15 per cent respectively with a trace of cerium.
Fully compacted graphite irons take combinations of properties intermediate between those of conventional chip and nodular irons, every bit shown in Tabular array 26.64. They behave elastically over a range of stresses although their limit of proportionality is lower than nodular irons. The tensile properties of compacted graphite irons are less sensitive to variations in carbon equivalent than conventional flake irons (Fig. 26.v) but they are section sensitive (Fig. 26.six).
Table 26.64. A COMPARISON OF THE MECHANICAL Properties OF Scrap, COMPACTED AND NODULAR GRAPHITE Bandage IRONS IN 30 MM BAR SECTIONS
| Flake graphite iron Grade 260 | Compacted graphite iron * (CEV = 4.iii) | Nodular graphite fe Form 500/7 | ||
|---|---|---|---|---|
| Ferritic | Pearlitic | |||
| Tensile strength, MN/mtwo | 260 | 365 | 440 | 500 |
| 0.i% Proof stress, MN/1000ii | 73 | 260 | 305 | 323 |
| 0.ii% Proof stress, MN/mtwo | — | 290 | 330 | 339 |
| 0.5% Proof stress, MN/m2 | — | 325 | 365 | 356 |
| Elongation % | 0.57 | iv.5 | 1.5 | 7 min–xv |
| Modulus of elasticity, GN/m2 | 128 | 162 | 165 | 169 |
| Hardness, HB 10/3000 | 185–226 | 140–155 | 225–245 | ~172 |
- *
- Irons produced by magnesium–titanium–cerium treatment.
Figure 26.5. Effect of carbon equivalent on the tensile strengths of flake, compacted and nodular graphite irons cast into 30 mm-diameter confined
Figure 26.6. Variation of tensile forcefulness with cast-department size for ferritic and pearlitic compacted graphite irons of various carbon equivalents. Each curve is the centre of a band of variation in force of about ±xxx MPa (± 2tonf/in2)
Compacted graphite irons have intermediate thermal electrical conductivity values betwixt flake and nodular iron and comparative figures are given in Table 26.65.
Table 26.65. A Comparing OF THE THERMAL CONDUCTIVITIES OF FLAKE, COMPACTED AND NODULAR GRAPHITE Bandage IRONS
| Thermal conductivity Due west/m 1000 | |||||
|---|---|---|---|---|---|
| 100°C | 200°C | 300°C | 400°C | 500°C | |
| Flake graphite fe (Grade 17) | 48.8 | 47.8 | 46.8 | 45.8 | 44.8 |
| Compacted graphite atomic number 26 (CEV = 4.three) | 41.0 | 43.5 | 41.0 | 38.5 | 36.0 |
| Nodular graphite iron (Form 500/7) | 35.5 | 35.35 | 35.ii | 35.05 | 34.9 |
Table 26.62. MECHANICAL PROPERTIES OF NODULAR IRONS
| Grade BS 2789: 1985 | Tensile force R m min | Proof stress R p0.2 min | Elongation A min % | Hardness HB | Impact Charpy 5-notch J * | Construction † | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| MPa | ksi | MPa | ksi | xx°C | −20°C | −xl°C | ||||
| 350/22L40 | 350 | 51 | 220 | 32 | 22 | ≤ 160 | — | — | 9(12) | F |
| 350/22 | 350 | 51 | 220 | 32 | 22 | ≤ 160 | 14(17) | — | — | F |
| 400/18/L20 | 400 | 58 | 250 | 36 | 18 | ≤ 179 | — | 9(12) | — | F |
| 400/18 | 400 | 58 | 250 | 36 | 18 | ≤ 179 | 11(14) | — | — | F |
| 420/12 | 420 | 61 | 270 | 39 | 12 | ≤ 212 | — | — | — | F |
| 450/10 | 450 | 65 | 320 | 46 | 10 | 160/221 | — | — | — | F/P |
| 500/seven | 500 | 72 | 320 | 46 | seven | 170/241 | — | — | — | F/P |
| 600/3 | 600 | 87 | 370 | 54 | iii | 192/269 | — | — | — | P/F |
| 700/two | 700 | 102 | 420 | 61 | ii | 229/302 | — | — | — | P |
| 800/2 | 800 | 116 | 480 | 70 | 2 | 248/352 | — | — | — | F or TS |
| 900/ii | 900 | 131 | 600 | 87 | 2 | 302/359 | — | — | — | TM |
Notes:
Verification of hardness and 0.2% proof stress is optimal.
- *
- Individual value. Value in brackets is mean of 3 tests.
- †
- F =ferrite, F/P = ferrite/pearlite, P/F = pearlite/ferrite, P =pearlite, TS =tempered structure, Th =tempered martensite.
The combination of relatively high strength and practiced thermal conductivity has resulted in compacted graphite irons primarily finding awarding where containment of stress at high temperature or under thermal cycling conditions are important. Applications for ingot moulds, cylinder heads, brakedrums and discs and manifold castings are typical.
British Standards are summarised for Austenitic irons BS 3468: 1986 Table 26.66, for alloy bandage irons BS 4844: 1986 in Tabular array 26.67 and for corrosion resisting high silicon irons BS 1591: 1975 in Table 26.68.
Table 26.66. AUSTENITIC CAST IRONS
| Form BS 3468:1986* | Composition % | Tensile forcefulness R m min | Proof strength R p0.2 min | Elongation A ** % | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C max | Si | Mn | Ni | Cr | Nb | P max | Other | MPa | ksi | MPa | ksi | ||
| General engineering | |||||||||||||
| F1 (FG) | 3.0 | 1.v/2.8 | 0.5/one.5 | xiii.5/17.5 | 1.0/two.5 | — | 0.2 | Cu 5.5/7.5 | 170 | 25 | — | — | — |
| F2 (FG) | 3.0 | 1.5/2.eight | 0.5/one.5 | 18.0/22.0 | one.5/2.5 | — | 0.two | Cu 0.5 max | 170 | 25 | — | — | — |
| S2 (SG) | three.0 | one.5/2.8 | 0.v/i.5 | 18.0/22.0 | i.five/ii.5 | — | 0.08 | Cu 0.5 max | 370 | 54 | 210 | xxx | 7 |
| S2W1 (SG) | three.0 | 1.five/two.2 | 0.5/1.five | 18.0/22.0 | 1.5/ii.5 | 0.12/0.2 | 0.05 | Cu 0.5 max | 370 | 54 | 210 | xxx | 7 |
| S5S (SG) | 2.2 | iv.8/5.four | 1.0 max | 34.0/36.0 | one.five/2.five | — | 0.08 max | — | 370 | 54 | 210 | thirty | 7 |
| Special purposes | |||||||||||||
| F3 (FG) | ii.five | 1.v/two.viii | 0.5/1.v | 28/32 | two.5/three.v | — | 0.two | Cu 0.5 max | 190 | 28 | — | — | — |
| S2B (SG) | iii.0 | ane.v/2.8 | 0.5/1.five | 18/22 | 2.5/3.5 | — | 0.08 | Cu 0.five max | 370 | 54 | 210 | 30 | 7 (4) |
| S2C (SG) | 3.0 | 1.5/2.8 | 1.5/2.v | 21/24 | 0.5 max | — | 0.08 | Cu 0.five max | 370 | 54 | 170 | 25 | 20 (20) |
| S2M1 (SG) | 3.0 | i.5/two.8 | 4.0/4.5 | 21/24 | 0.five max | — | 0.08 | Cu 0.five max | 420 | 61 | 200 | 29 | 25 (15) |
| S3 (SG) | 2.5 | one.5/2.8 | 0.5/1.five | 28/32 | 2.v/iii.five | — | 0.08 | Cu 0.5 max | 370 | 54 | 210 | 30 | 7 |
| S6 (SG) | 3.0 | 1.v/2.8 | vi.0/7.0 | 12/xiv | 0.ii max | — | 0.08 | Cu 0.five max | 390 | 57 | 200 | 29 | 15 |
- *
- (FG)= Chip graphite, (SG) = speroidal graphite.
- **
- Value in bracket is Charpy V notch strength at 20°C in J.
Table 26.67. Alloy CAST IRONS
| Course BS 4844: 1986 | Composition % | Hardness | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| P | HB | HV | |||||||||
| C | Si | Mn | Ni | Cr | max | Other | (Department thickness mm) | ||||
| Low alloy grades | |||||||||||
| 1A | ii.4/3.iv | 0.five/one.v | 0.two/0.8 | — | 2.0 max | 0.fifteen | — | 400(<50) | 350(>l) | 428(<50) | 368(>50) |
| 1B | 2.4/3.4 | 0.5/1.5 | 0.2/0.8 | — | two.0 max | 0.v | — | 400(<50) | 350(>fifty) | 428(<50) | 369(>50) |
| 1C | 2.4/3.0 | 0.5/1.5 | 0.2/0.eight | — | 2.0 max | 0.xv | — | 250(<50) | 225(>l) | 225(<50) | 205(>50) |
| Nickel chromium grades | |||||||||||
| 2A | 2.7/3.ii | 0.3/0.8 | 0.ii/0.8 | 3.0/5.five | ane.five/iii.five | 0.15 | Mo 0.five | 500(<125) | 450(>125) | 542(<125) | 485(>125) |
| 2B | 3.2/3.six | 0.3/0.8 | 0.2/0.8 | 3.0/5.five | ane.5/three.5 | 0.15 | Mo 0.5 | 550(<125) | 500(>125) | 599(<125) | 542(>125) |
| 2C | two.4/ii.viii | 1.five/2.two | 0.two/0.8 | 4.0/vi.0 | 8.0/ten.0 | 0.ten | Mo 0.v | 500(<125) | 450(>125) | 542(<125) | 485(>125) |
| 2D | 2.eight/three.2 | 1.5/2.two | 0.2/0.8 | four.0/6.0 | 8.0/x.0 | 0.10 | Mo 0.v | 550(<125) | 500(>125) | 599(<125) | 542(>125) |
| 2E | 3.2/3.six | 1.5/ii.2 | 0.ii/0.8 | 4.0/vi.0 | 8.0/10.0 | 0.10 | Mo 0.five | 600(<125) | 550(>125) | 655(<125) | 599(>125) |
| Loftier chromium grades | |||||||||||
| 3A | i.eight/three.0 | 1.0 max | 0.5/ane.5 | 2.0 max | 14/17 | 0.10 | Mo/Cu 2 max | 600 min | 655 min | ||
| 3B | iii.0/3.six | 1.0 max | 0.5/i.5 | 2.0 max | 14/17 | 0.x | Mo/Cu ii max | 650 min | 712 min | ||
| 3C | 1.viii/iii.0 | ane.0 max | 0.5/i.5 | 2.0 max | 17/22 | 0.10 | Mo/Cu 2 max | 600 min | 655 min | ||
| 3D | 2.0/ii.8 | one.0 max | 0.five/i.five | two.0 max | 22/28 | 0.ten | Mo/Cu 2 max | 600 min | 655 min | ||
| 3E | 2.8/3.five | 1.0 max | 0.5/one.5 | 2.0 max | 22/28 | 0.10 | Mo/Cu ii max | 600 min | 655 min | ||
| 3F | 2.0/ii.7 | ane.0 max | 0.5/1.5 | two.0 max | 11/xiii | 0.10 | Mo/Cu 2 max | 600 min | 655 min | ||
| 3G | 2.7/three.four | 1.0 max | 0.5/1.v | two.0 max | eleven/13 | 0.ten | Mo/Cu ii max | 650 min | 712 min | ||
Table 26.68. CORROSION RESISTING HIGH SILICON Bandage IRONS
| Grade BS 1591: 1975 | Composition % | Application | |||||
|---|---|---|---|---|---|---|---|
| C max | Si | Mn max | P max | S max | Cr | ||
| Si10 | 1.2 | ten.0/12.0 | 0.5 | 0.25 | 0.1 | — | Strength greater than S14 |
| Si14 | 1.0 | 14.25/15.25 | 0.5 | 0.25 | 0.ane | — | General corrosion |
| Si Cr 144 | 1.four | 14.25/15.25 | 0.5 | 0.25 | 0.1 | 4.0/v.0 | Cathodic protection anodes |
| Si16 | 0.8 | 16.0/18.0 | 0.v | 0.25 | 0.1 | — | Corrosion resistance at expense of strength |
Heat treatment: Castings to be stripped from moulds while hot and as soon as possible after solidification, the hot castings to be charged to a furnace preheated to approximately 600°C and kept at this during charging. And so oestrus to non less than 750°C and not more 850°C. Soak for 2 hours for castings of simple course and thickners less than 18 mm and for viii hours for heavy castings. Absurd slowly after soak to 300°C before unloading.
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Reciprocating compressors
Maurice Stewart , in Surface Product Operations, 2019
9.8 Materials of construction
The post-obit is a description of the materials bachelor for the major components of a reciprocating compressor.
9.8.ane Crankshafts
Crankshafts are normally jumpsuit forgings or castings. Steel or nodular atomic number 26 castings are sometimes used for machines up to 1500 HP. The advantages of castings are that counterweights tin be an integral part of the shaft. Most companies prefer forged steel for ratings of 200 HP and higher. A typical material designation is ASTM A688 Form F.
nine.8.2 Piston rods
The most mutual cloth used is estrus-treated AISI 4140 steel with a maximum Rockwell "C" hardness of 40 at the core and a minimum of 50 at the surface. If stress corrosion is a design cistron, this fabric is annealed to a hardness of 22C maximum (cadre) and 50C minimum (surface). AISI 8620 with the aforementioned hardness provides college working stresses for stress corrosion applications.
Rods of 17-4 pH stainless steel are used for corrosive services. Core and surface hardness are 40-50C for standard applications. When stress corrosion is nowadays, the through-hardness is limited to 33C.
9.8.3 Crossheads
Crossheads are available in cast gray iron, nodular iron, or steel. Most companies prefer bandage steel for all loftier-horsepower applications. It is recommended that cast grayness iron be allowed only on smaller machines with ratings less than about 200 HP.
9.viii.iv Connecting rods
Connecting rods should be forged steel. A typical material designation is ASTM A235.
9.8.5 Compressor cylinders
The maximum allowable working pressure (MAWP) respective to materials is typically limited to the valves given in Table 9.v . Note that nodular iron may be used in machines in a higher place 1000 psig merely in special cases. Nodular fe is an first-class engineering science material, but homogeneity of the material throughout the casting can sometimes exist a problem. Thus the yield strength may not be as high as anticipated. API 618 calls for specimen testing and other NDE in an endeavour to ensure the quality of nodular atomic number 26 castings.
ix.8.6 Compressor valves
Valve materials are selected for both durability (long-term functioning) and compatibility with the gas existence handled. Table 9.6 presents materials for valve guards and seats. Valve plates are bachelor in various types of stainless steels and thermoplastics, every bit given in Tabular array 9.7. Table 9.eight presents the broad variety of spring materials available, from music wire to Inconel. Other super alloys, such as Elgiloy and Haynes 25, are existence used to avoid hydrogen embrittlement for springs.
Table 9.6. Typical baby-sit and seat materials for compressor valves
| Material | Application |
|---|---|
| 1141 | Light duty noncorrosive service |
| Heat Treated 1141 | Calorie-free to medium noncorrosive service |
| Ductile Atomic number 26 | Light to medium service—resistance to some chemic attack |
| 4140 | Medium to high forcefulness—resistance to some chemical attack |
| Heat Treated 4140 | High strength service—resistance to some chemical attack |
| 400 Series Stainless Steel | Corrosive service |
| 300 Series Stainless Steel 17-4 PH Stainless Steel | Extreme corrosive service |
Table 9.7. Typical valve plate materials
| Material | Application |
|---|---|
| Glass-filled nylon thermoplastic | Practiced impact and corrosion resistance 270°F temperature limit |
| Peek—Polyetheretherketone | Loftier strength—high temperature (up to 375°F) |
| Linen-Based Phenolic Laminate | Clean gas. depression compression ratios. 225°F temperature limit |
| Laminated cloth-based phenolic | High-temperature applications up to 400°F—available for ported plate application only |
| 410 Stainless steel | moderate corrosion resistance, good bear on resistance |
| 17-7 PH stainless steel | Moderate corrosion resistance, skilful impact resistance |
| Inconel X-750 | High corrosion resistance and loftier forcefulness properties in high-temperature applications |
Tabular array 9.8. Typical valve bound materials
| Material | Application |
|---|---|
| Music Wire | Low corrosion resistance. proficient durability in clean gas environments and depression temperatures |
| 302 Stainless Steel | Moderate corrosion resistance. Average durability in moderate temperatures |
| 17-7 FH Stainless Steel | Excellent corrosion resistance, high strength properties in moderate/high temperatures (700°F Max) |
| Inconel 10-750 | Loftier corrosion resistance, high strength properties in high-temperature applications (1100°F Max) |
Surface terminate and parallel face surfaces are the most serious considerations for metallic plates. Dimensional stability or thermoplastic plates in boiling and high-temperature environments is essential. 1 disadvantage to the use of thermoplastic plates is their affinity for wet, called hygroscopicity. Newer materials, such equally PEEK and TORLON, have lower assimilation rates (0.06%) than nylon glass composites (1%). Likewise, some of the materials accept a lower coefficient of thermal expansion. A low thermal expansion factor makes the plate more resistant to deformation at higher temperatures and meliorate able to hold dimensional integrity.
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Casting Alloys
John Campbell , in Complete Casting Handbook (Second Edition), 2015
6.v.ix Chunky Graphite
Chunky graphite is oftentimes observed concentrated in the centers of heavy sections of nodular iron castings. 'Chunky' is not a specially helpful descriptive adjective for this variety of graphite. Its 'chunkiness' is only apparent under the microscope at high magnification; otherwise, it simply appears to exist fine, irregular, branched and interconnected fragments ( Figures 6.52(c) and 6.55). Once once more, the properties of nodular iron are reduced. However, it seems the loss of properties may, again, exist at least partly associated with the short diffusion distances between branches of the graphite filaments, promoting the development of ferrite instead of the stronger pearlite eutectoid phase (Liu et al., 1983).
Figure half dozen.55. Graphite nodules and areas of fine, mesomorphic graphite in the thermal heart of a 200 mm cube casting (Kallbom, 2006).
Liu and co-workers (1980, 1983) found evidence that chunky graphite grows along the C-centrality direction, as does both nodular and compacted graphite. Furthermore, they reported observations on spheroids that exhibit gradual degeneration, gradually taking on the growth forms of chunky graphite. Thus they concluded that mesomorphic graphite is a degenerate class of spheroidal graphite, and their work implied that mesomorphic graphite grows out from spheroids. Itofugi and Uchikawa (1990) confirmed the identical growth modes of spheroidal, compacted and chunky graphites equally illustrated schematically in Figure half-dozen.52.
All these workers observed the feature form of chunky graphite, as an apparently 'terminate/start' growth in the C-direction consisting of most carve up pyramidal 'chunks' linked by a narrow neck, similar beads on a string (Figure vi.52(c)). The individual clamper sections comprise layers parallel to the basal plane, just simply nanometres thick. This characteristically lumpy growth may be the result of a pulsating or irregular advance of the growth front, with the austenite advancing to nearly grow over the top of the graphite, forming the almost pinched-off neck of the graphite, only to be overtaken once again because the carbon in solution will now buildup in the liquid ahead of the front, accelerating the next stage of growth of the graphite until the local carbon concentration is depleted once again.
Observations by Kallbom and co-workers (2006) are consistent with an origin associated with bifilms. They observe the mesomorphic graphite to be concentrated in the center of heavy sections, explained by the growth of the freezing front pushing bifilms ahead, and explaining their observations of 'stringers' of graphite nodules. These features are almost certainly sheets of oxides decorated with graphite nodules that have been nucleated on the oxide (analogously to those seen in Figure 6.32). The earlier paper by these authors (Kallbom, 2005) described how the outer several centimetres of the casting tin can be perfect, with good nodularity, good forcefulness and ductility, but the structure can change abruptly, over a short distance equivalent to but a nodule diameter, to chunky graphite. Thus the cardinal volume of the casting is weak and brittle. Because the problem is buried in the center of thick section castings it can be difficult to find past non-destructive methods.
All previous evidence that suggests chunky graphite requires both the presence of bifilms combined with an absence of nuclei. It is possible to imagine a mechanism in which following a turbulent pour, many bifilms will be pushed alee of the forest of growing dendrites, forming, at times, a singled-out and abrupt separation of the outer dendritic region from the inner residual liquid. The presence of the concentration of bifilms in the centre volition suppress the normal pattern of free circulation that would ensure a expert supply of nodules from the outer, cooler regions into the hot central region. Furthermore, because so much time is bachelor, particles such as nuclei and nodules already in suspension in the eye will have fourth dimension to float out, or existing nodules to dissolve (because they will be unstable at these college temperatures) depleting the centres of nuclei so that spheroids cannot form.
For those nuclei now floated out to the edge of this region of higher temperature and enhanced segregation, any nodules formed on the nuclei volition not enjoy the benefit of a surrounding austenite shell, so that their growth machinery will more well-nigh resemble that of an exploded spheroid. Because these volition be at the boundary of the central region, their growth is most likely to be an extension of the nodules along the C-axis (Liu et al., 1980) in the management of the gradually advancing solidification front. In the absence of nuclei, the whole region would be expected to make full with this continuous growth course. The extended size of chunky graphite regions, much larger than cells of other types of graphite (Itofugi and Uchikawa, 1990), corroborate the absence of nuclei in these regions.
The presence of bifilm cracks full-bodied in the chunky graphite regions would explain the poor backdrop that are observed; it is difficult to see how otherwise a continuous graphite stage could reduce properties, specially considering in other irons (such equally CGI) a continuous graphite phase is associated with excellent and reproducible tensile properties.
It is hoped that in the nearly future the explanation for the origin of chunky graphite might be clarified and confirmed by further careful experiments. The cardinal word here is 'careful'. For instance, the experiment by Asenjo and co-workers (2009) involving the placement of inoculants in unlike branches of a runner system to simulate the casting of separate moulds from one cook. In this way, it should have been possible to compare the effects of different mould inoculation in split heavy castings. The idea was clever, but regrettably experimentally flawed because, in common with virtually iron casting, the runners were not designed to be pressurised and fill on a single pass. Thus a opposite catamenia is probable to have contaminated the mould cavities, and all the bandage material would have suffered from turbulence and air entrainment. All the cavities would therefore have been contaminated with varying amounts of inoculants from neighbouring cavities, and all would have contained unknown quantities of oxide bifilms. Clearly, in the futurity, much greater sophistication of melting and casting will be required for experiments designed to clarify the solidification mechanisms for cast irons.
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Life Cycle Tribology
Simon C. Tung , ... Xianghuai Dong , in Tribology and Interface Engineering Serial, 2005
3.2 TOOLING Material Comparison
Three tooling materials were evaluated in the nowadays study at a constant load of 200N: GM 238 grey cast iron and 246 pearlitic nodular iron, and 1040 steel. The tooling materials were evaluated using a variety of lubricants and tested both with the lubricant simply on the tooling (summarized in Table ii), and too with lubricant on both the tool and the 5083 aluminum sample. No significant differences in behavior were observed among the three tooling materials. Still, there are some modest differences which may suggest that larger differences in beliefs could exist, particularly when larger numbers of panels are run in a product environment. The all-time condition for distinguishing betwixt die materials occurred when the aluminum sheet was lubricated and no lubricant was applied to the dice (Table 2). Under these conditions, the 1040 steel showed slightly higher friction when boron nitride and molybdenum disulfide were used, and slightly more wearable (along with GM 238) when magnesia was used. While these differences may not exist pregnant, additional research should exist conducted to sympathise the effect of tooling fabric on friction and wear.
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Reciprocating pumps
Maurice Stewart , in Surface Production Operations, 2019
four.iv.one.2 Crankshaft
The crankshaft (Figs. 4.thirty–4.32 ) varies in construction depending on design and ability output. In horizontal pumps, the crankshafts are unremarkably constructed of nodular iron or cast steel. Vertical pumps are constructed of forged steel or machined billet for high pressure. Since crankshafts operate at relatively low speeds and mass, counterweights are not used. Except in the case of duplex pumps, crankshafts are usually made with an odd number of throws to obtain the best pulsation characteristics. The firing social club in a revolution depends upon the number of throws on the crankshaft, every bit presented in Tabular array 4.8. Many designs incorporate rifle drilling between throws, thus furnishing lubrication to the crankpin bearings.
Fig. 4.30. Schematic diagram of a cast crankshaft.
Courtesy of Ingersoll Rand Company. 
Fig. iv.31. Example of a crankshaft machined from a billet. Top: prior to machining; Heart: barracks during the machining procedure; and Lesser: final production.
Courtesy of Ingersoll Rand Company. 
Fig. 4.32. Example of a cast crankshaft with an integral gear.
Courtesy of Continental EMSCO. Tabular array 4.8. Order of pressure level buildup, or firing order
| Throw from caster end | No. of plungers or pistons | Pressure level buildup order | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | v | vi | 7 | 8 | 9 | ||
| Duplex | 2 | 1 | 2 | |||||||
| Triplex | 3 | 1 | 3 | 2 | ||||||
| Quintuplex | 5 | 1 | iii | 5 | 2 | 4 | ||||
| Septuplex | vii | 1 | 4 | vii | 3 | 6 | two | 5 | ||
| Nonuplex | nine | 1 | v | 9 | 4 | eight | 3 | 7 | ii | 6 |
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Gas turbines: operating weather, components and material requirements
A.Westward. James , Due south. Rajagopalan , in Structural Alloys for Power Plants, 2014
1.two Overview of materials systems and their office in gas turbines
Materials and materials systems play a central role in the part of the gas turbine, and appropriate materials choices are essential to maximizing gas turbine efficiency and operational longevity. The compressor section of the gas turbine is predominantly manufactured from ferrous alloys, namely steels and nodular irons. The temperature within the compressor increases from ambient at the inlet to nearly 600 °C in the final stages towards the compressor exit. Materials used for the blades and vanes in the rear compressor stages must have adequate high temperature strength and oxidation resistance to withstand these conditions. Other important material property requirements include good corrosion resistance and high cycle fatigue strength. Stainless steels are the preferred materials for compressor blades and vanes. Examples of the prominently used grades include 17-4 PH (a precipitation hardenable grade) and 400 series martensitic stainless steels. Where additional protection against corrosion is required, coatings (such as alumina) may exist practical.
The compressor external flow path is defined by the casing. While the casing for the inlet portion of the compressor is typically made of either carbon steel or nodular fe, the remainder of the compressor casing is commonly made of a depression blend steel. Stainless steels maybe used towards the rear finish of the compressor, where the temperatures are also loftier for depression alloy steel. Combustion and turbine casings operate at college temperatures than the compressor. The casings materials for the turbine and combustor are ofttimes manufactured from heat-resistant steels: alloy steels such as 2.25%Cr steel or stainless steels such as 400 series martensitic stainless steels.
The rotor is a disquisitional component, extending from the front of the compressor to the rear of the turbine section carrying both the compressor and turbine blades. The rotor consists of a series of disks that either are bolted or welded together to form the rotor or affixed to a central shaft. The rotor disks experience pregnant centrifugal loads resulting from the blades fastened to the outer diameter. Disk materials must have relatively loftier tensile forcefulness, too as very skilful fatigue and fracture properties. Disks at the front stages of the compressor may be exposed to low ambient temperatures, and the need for good fracture toughness at sub-nada temperatures is important for these stages. In contrast, the disks at the rear cease of the compressor experience relatively high temperatures and must therefore exhibit skilful pitter-patter properties. High forcefulness low alloy (HSLA) steels, e.thou. three.5NiCrMoV steel, meet the mechanical property requirements for forepart compressor disks and are likewise relatively depression price. There is a need to transition from low alloy steels to creep-resistant steels once the temperatures start to exceed 300–350 °C. Twelve pct chromium steels or martensitic stainless steels are oft preferred for the last compressor stages, where temperatures exceed 400 °C, due to their good elevated temperature forcefulness and creep properties. At temperatures beyond well-nigh 550 °C steels practise not have sufficient creep strength for deejay applications, and at these higher temperatures information technology is necessary to employ solid solution strengthened or gamma prime (γ′) strengthened nickel-based alloys. With the appropriate composition and microstucture, nickel-based superalloys may exist used for deejay applications at temperatures of upwards to effectually 700 °C (Reed, 2008).
From a materials and design perspective the turbine department probably represents the most challenging environment in the gas turbine. The temperature of the working fluid entering the turbine section frequently exceeds the useful working temperature limit of nickel-base superalloys, and in the most advanced industrial gas turbines the gas path temperatures can hands exceed the melting temperature of the blade and vane alloys past several hundred degrees Celsius. This demands the use of effective cooling schemes and protective thermal barrier coatings.
Superalloys are typically the material of choice for turbine hot gas path components (blades, vanes and ring segments). The γ′ strengthened superalloys exhibit a unique behavior, maintaining their strength and creep properties up to approximately 0.vii times their melting temperature. The superalloys have been the subject of extensive evolution efforts driven primarily by the aero engine industry. The development has focused both on compositional modifications and on processing. The nickel-base alloys take progressed through a number of 'generations' characterized by increasing amounts of rhenium (Re) and ruthenium (Ru). However, while the creep resistance of the alloys has increased significantly, so has the cost. While the superalloys with half dozen% Re and 6% Ru are tailored specifically for aero engine applications, they are non well suited to use in big industrial gas turbines. The casting of large monolithic single crystal industrial gas turbine components can be very challenging, and the high bit rates accompanied past the very loftier cost of the alloy brand the employ of these alloys prohibitively expensive for industrial gas turbine (IGT) applications.
Coatings are an integral part of many IGT materials systems, contributing several primal functions including thermal and oxidation protection, clearance command and habiliment resistance (Clarke and Phillpot, 2005; Padture et al., 2002). With the push towards increased efficiency, reduction in cooling air for blades and vanes is an essential design requirement driving the need for increased thermal protection from the coating organization. Porous abradable coatings deposited on ring segments enable the reduction of gaps between bract tips and the ring segments arising from engine build tolerances. The reduced leakage over the blade tips leads to further increases in efficiency and power. Component mating interfaces, such every bit combustor bound clips, experience significant sliding move resulting in local component wear, and article of clothing-resistant coatings serve to alleviate this distress.
Thermal barrier blanket (TBC) systems consist of an oxidation-resistant metallic coating, deposited on top of a superalloy substrate, with a porous ceramic coating on top. The ceramic coating provides thermal insulation to the underlying superalloy and bail glaze. The metallic coating performs the dual functions of providing adherence for the ceramic coating and oxidation resistance for the superalloy. Such oxidation protection is particularly of import following spallation of the TBC. The metallic bail coat is typically applied to the component using a thermal spray process such as depression pressure plasma Spray (LPPS) or loftier velocity oxy-fuel (HVOF). Figure one.3 schematically represents a department through such a multi-layer protection system. The thickness of the coatings are typically one-tenth to i-fifth the thickness of the superalloy substrate, depending upon the component. Typically, coatings on blades and vanes are thinner (300–500 μm) than those used in combustors (about 1 mm or higher). Zirconia-base TBCs are widely used as the ceramic blanket on the surfaces of high-temperature engine components. The microstructures and properties of TBCs are largely defined by the processing parameters. For case, plasma spray (PS) and electron beam–physical vapor deposition (EB-PVD) produce distinctively different microstructures and thermomechanical characteristics. Each of these processing techniques has advantages and disadvantages. The size of the underlying component, performance requirements, and price are key factors in the choice of a TBC organisation.
1.three. Schematic representation of a department through a multilayer thermal and oxidation protection system.
Used with permission from Siemens Energy, Inc.Ceramic abradables are used in the turbine section of both aero and industrial gas turbines to allow reduced hot running clearances between the rotating blades and stationary shrouds or band segments. The benefits of tighter running clearances include increased power, efficiency and reduced emissions. For a modern industrial gas turbine, a i mm reduction in the Row 1 and Row 2 turbine blade tip clearance is worth in backlog of United states$1 million. This benefit does not come up without some risk, however. If the abradable system is not called correctly for the specified awarding, the blade tips can be damaged, removing cloth from the tips and resulting in increased gas leakage for that row of blades. Criteria for choosing abradables include operating temperature, incursion rate (rate at which the radial gap changes during bract rubbing) and fourth dimension before cut occurs (ideally the blades would brainstorm to cut into the abradable blanket during the first rotation on starting the engine). The blade tips themselves may be left uncoated or coated with an annoying for improve cut of the abradable coating.
Wear-resistant coatings have been disquisitional to the performance of gas turbines in aircraft and land-based applications. Gas turbine components are subjected to harsh environments that include rigorous mechanical loading weather condition. Many compressor, combustion and turbine components experience vibrations and dynamic forces that cause wear. These components tin can be coated with vesture-resistant coatings to increase maintenance intervals and ensure that components come across their intended design lives.
Coatings are a disquisitional component of the 'materials organization' for hot department turbine components. The commencement 2 rows of turbine blades, vanes and ring segments are commonly protected with two dissever coatings, a metallic bond glaze and a ceramic thermal barrier coating. The bond glaze is unremarkably in the form of an MCrAlY (where G is either Co or Ni). Equally the name suggests, the bond coat is an interlayer between the substrate blend and the TBC which helps 'bond' the TBC to the underlying alloy.
Towards the rear of the turbine section where the temperatures are lower, TBC are not required. All the same, metallic overlay coatings are very often applied to provide oxidation and corrosion protection to the underlying superalloy. Some cooled components utilize internal coatings for oxidation or corrosion protection. Internal coatings are often applied using chemic vapor deposition (CVD). A summary of the typical temperatures ranges and materials at the various locations within an industrial gas turbine is given in Table 1.one.
Table 1.1. Typical operating temperature ranges and materials for gas turbine components
| Location | Component | Typical temperature (°C) range | Typical class of materials |
|---|---|---|---|
| Compressor inlet | Compressor blades | Ambience (− 30 to + 45) | Precipitation hardenable stainless steels |
| Compressor vanes | Ambience (− 30 to + 45) | Martensitic stainless steels | |
| Compressor disks | Ambient (− xxx to + 45) | High force low alloy steels | |
| Compressor outlet | Compressor blades | Upwardly to 450 Upwards to 600 | Martensitic stainless steels γ′ strengthened nickel-base superalloys (cast or wrought: equiaxed) |
| Compressor vanes | Up to 450 Up to 600 | Martensitic stainless steels γ′ strengthened nickel–base superalloys (bandage or wrought: equiaxed) | |
| Compressor disks | Up to 550 | High force low alloy steels; 12%Cr creep-resistant steels | |
| Combustor | Combustor | Upwardly to 800 | Solid solution strengthened nickel-base of operations superalloys Stainless steels |
| Combustor to turbine | Transition duct | Upwards to 800 | Solid solution strengthened nickel-base superalloys |
| Turbine inlet | Turbine blades | 1200–1600 | γ′ strengthened nickel-base of operations superalloys (cast: unmarried crystal, directionally solifidied or equiaxed) |
| Turbine vanes | 1200–1600 | γ′ strengthened nickel-base superalloys (cast: unmarried crystal or equiaxed) Cobalt-based superalloys | |
| Turbine disks | 450–550 500–650 | Loftier force low blend steels; 12%Cr steels | |
| γ′ strengthened nickel-base superalloys (wrought: equiaxed) | |||
| Turbine get out | Turbine blades | 500–600 | γ′ strengthened nickel-base superalloys (cast: equiaxed) |
| Turbine vanes | 500–600 | γ′ strengthened nickel-base superalloys (cast: equiaxed) Cobalt-based superalloys | |
| Turbine disks | 450–550 | Steel | |
| Outer casing | Outer casing | Up to 600 | Cast atomic number 26 |
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Fatigue Design of Components
Kenneth Hamberg , ... Anders Robertson , in European Structural Integrity Society, 1997
INTRODUCTION
Nodular bandage iron is a textile that has found a increasing number of applications in the automotive industry during the last decade. It has a static strength comparable to bandage steels and a greater fatigue forcefulness and ductility than grey irons. Castability and machinability is good, and all these properties makes information technology an economic culling for medium stressed components and for rubber critical applications. A reduction of 30% or more in component cost tin can exist fabricated when nodular atomic number 26 is substituted for cast or forged steel [1]. Nodular iron is however a material that contains different kinds of defects, such every bit inclusions, dross, surface defects, slag stringers and micro shrinkage pores. It has been plant that cracks will initiate and propagate from these defects. The degree to which these different defects will lower a components service life is not fully investigated [2,3]. A dominion of thumb is that the rough bandage surface lowers the fatigue functioning to the same level independently of the grade of the material.
The present work is a study of the lifetime for exam specimens in nodular bandage iron with an as cast surface marred past surface defects. The assay and calculations are based on fracture mechanics.
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Rolls-Royce/MTU
Malcolm Latarche , in Pounder'southward Marine Diesel Engines and Gas Turbines (Tenth Edition), 2021
BV engine
The first BV engines—twin V12-cylinder models, each developing 5294 kW at 750 rev/min—were delivered in 1998 for powering a large anchor handling/tug/supply vessel (Fig. 23.1 ). The BV design is based on a single-slice engine block cast in GGG500 nodular iron carrying 2 banks of cylinders in a 55° 5-configuration ( Fig. 23.2), an underslung crankshaft (Fig. 23.3) and two camshafts; it too incorporates the accuse air receiver between the cylinder banks. The camshafts are located outside each banking concern and housed in open up-sided recesses in the cake, allowing the consummate camshafts to be removed sideways. At the forepart of the block is an opening for the accuse air cooler and some other for the auxiliary gear drive; the timing gears are arranged at the rear of the engine. The whole structure is designed for firing pressures in excess of 200 bar. An advantage of the block material is that it can be repaired past welding in the effect of accidental harm.
Fig. 23.1. A Bergen B32:forty engine in V12-cylinder form.
Fig. 23.2. The BV engine cake is a nodular fe casting.
Fig. 23.3. Crankshaft of the BV engine.
A new cylinder liner pattern specified for the BV engines features a thicker upper wall department than the in-line cylinder BR models and a revised bore-cooling layout (Fig. 23.4). The liner, rated for mean effective pressures up to 32 bar and elevation pressures in excess of 220 bar, was later on standardized for all B-series engines. Small changes were fabricated to the BV cylinder heads, mainly a new head gasket matching the redesigned liner. The two-piece piston is essentially the same as that used in the BR engines, with a nodular iron skirt and bore-cooled steel crown. The connecting rods were diffuse simply the aforementioned bearings were used as before.
Fig. 23.4. BV engine cylinder liner with the bore-cooled upper office, also applied to the in-line cylinder BR models.
Shorter fuel injection periods dictated strengthened camshafts to encounter the increased loads, with a larger bore both for the shaft and for the cam base circles. The fuel pumps are the aforementioned equally those for BR engines but the fuel supply arrangement was modified, chiefly by increasing pipe volumes and changing the layout to avoid cavitation and smooth out vibration caused by pressure pulses from the pumps.
Twin turbochargers mounted above the two insert-type charge air coolers operate on the impulse system, the pipework enclosed in an insulated box between the cylinder banks. A choice of electronic governors is offered, operating in conjunction with a standardized hydromechanical actuator. All electrical transducers on the BV engine are linked to a mutual electric runway, one on each side of the engine, in a neat layout enabling faulty transducers to be rapidly changed.
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