1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1988 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001INFORMATIONREPORTAn American National StandardJ125REAF.MAY88Issued 1969-
4、09Reaffirmed 1988-05Superseding J125 SEP69ELEVATED TEMPERATURE PROPERTIES OF CAST IRONSForewordThis Document has not changed other than to put it into the new SAE Technical Standards Boardformat.This document is currently under revision.1. ScopeThe purpose of this SAE Information Report is to provid
5、e automotive engineers and designers with aconcise statement of the basic characteristics of cast iron under elevated temperature conditions. As such,the report concentrates on general statements regarding these properties with limited illustrative data,anticipating that those who may be interested
6、in more detail will want to use the bibliography provided at theconclusion of the report.2. References2.1 Related PublicationsThe following publications are provided for information purposes only and are not arequired part of this document.2.1.1 OTHER PUBLICATIONS1. “Mechanical Properties of Metals
7、and Alloys.“ U.S. Dept. of Commerce Circular C-447, NationalBureau of Standards, 1943.2. Kattus and McPherson, “Properties of Cast Iron at Elevated Temperatures.“ ASTM Special TechnicalPublication No. 248.3. Malleable Iron Casting Handbook. Malleable Founders Society, 1960.4. Gray Iron Castings Hand
8、book. Gray Iron Founders Society, Inc., 1958.5. Cast Metals Handbook. American Foundrymens Society, 1957.6. Colin J. Smithell, “Metals Reference Book.“ Washington Butterworths, 1962.7. Metals Handbook, 8th Edition. American Society for Metals, 1961.8. “Engineering Properties of Ductile Ni-Resist Aus
9、tenitic Irons.“ International Nickel Co., 1955.9. Schelleng and Eash, “Effect of Composition on the Elevated-Temperature Properties of Ductile Iron.“Proceedings of ASTM, Vol. 57, 1957.10. Greene and Sefing, “Cast Irons in High Temperature Service.“ Corrosion, Vol. 11, No. 7, July 1955.11. Turnbull a
10、nd Wallace, “Molybdenum Effect on Gray Iron Elevated Temperature Properties.“Transactions AFS, Vol. 67, 1959.12. F. B. Foley, “Mechanical Properties at Temperature of Ductile Cast Iron.“ Preprint No. 55-A-204,ASME, 1955.13. Engineering Properties of Ni-Resist Ductile Irons.“ International Nickel Co.
11、, 1958.SAE J125 Reaffirmed MAY88-2-14. Elevated Temperature Properties of Ductile Cast Irons.“ ASM Transactions, Vol. 47, 1955.15. Scholz, Doane, and Timmons, “Effects of Molybdenum on Stability and High Temperature Propertiesof Pearlitic Malleable Iron.“ AFS Transactions, Vol. 63, 1955.16. D. A. Pe
12、arson, “Stress-Rupture and Elongation of Malleable Iron at Elevated Temperatures.“ AFSTransactions, Vol. 74, 1966.17. W. L. Collins, “Fatigue and Static Load Tests of an Austenitic Cast Iron at Elevated Temperatures.“ASTM Proceedings, Vol. 48, 1948.3. IntroductionCast irons, like steels and other me
13、tals, lose strength as operating temperatures increase.Composition is of importance not only because of its effect on the basic properties of materials at elevatedtemperatures, but also because in cast irons it influences growth resulting from oxidation and microstructuralchanges. Irons may be used
14、in most atmospheres at temperatures up to 750 F without growth being a seriousfactor. Beyond 900 F graphitization can cause growth and above 1200 F internal oxidation can cause growthunless sufficient alloy is present to prevent it.Deterioration of properties at high temperatures is in general time-
15、dependent as well as temperature-dependent. Even at temperatures where strength has been greatly reduced, many useful hours of life can beobtained from a structure if proper allowances are made in the initial design. Where applications involvesustained stress at high temperature, the most valuable i
16、nformation for the designer is the creep rate at thetemperature and stress involved. However, creep rate data generally involve long time tests and as aconsequence complete information has not been generated for all materials under all conditions. Instead, ithas been the practice for many years to c
17、ompare materials in shorter duration tests. Such tests are calledstress-to-rupture tests or more simply stress-rupture tests. These are conducted in the temperature ranges ofinterest but usually at much greater loads than any realistic design. In general, materials showing superiorstress-rupture lif
18、e have the lowest creep rates. This type of information has been used primarily for materialdevelopment work. It can be used by the designer, however, to select better material on a comparison basis.Several types of iron are included in this section to show trends; they are representative of broad c
19、lasses ofirons used commercially, and for which thermal data are available in the literature.4. Effect of Elevated Temperature on Mechanical Properties4.1 Tensile StrengthThe tensile strength of ferrous materials generally shows small changes from roomtemperature up to 600800 F, at higher temperatur
20、e the strengths usually fall rather rapidly. The presence ofalloying elements which affect the stability of the higher strength microstructures tends to delay this effect orraise the temperature at which rapid loss of strength occurs. In some ferrous alloys, changes in microstructureoccur at tempera
21、tures between room temperature and 800 F which may cause small changes in strength and,in fact, may cause reversals in the strength versus temperature curve. In Figure 1, examples of tensile strengthversus temperature for some typical cast irons are illustrated in comparison with the behavior of low
22、 carbonsteel. Generally, the changes in structure which occur over this temperature range are associated withtempering after hardening. These changes are irreversible.SAE J125 Reaffirmed MAY88-3-FIGURE 1ELEVATED TEMPERATURE TENSILE STRENGTH4.2 Stress Rupture PropertiesWhere metals are required to su
23、stain loads over long periods of time at elevatedtemperatures, the stress-rupture test is used as an indication of the relative load-carrying ability at the testtemperature.TABLE 1CHEMICAL COMPOSITION FOR CAST IRONS SHOWN IN FIGURES 17Material Alloying, %T.C. C Si Mn P S Cr Ni Mo MgAlloy gray cast i
24、ron (ASTM A 48, No. 60) (2)(1)1. Parenthetical numbers indicate source of data in 2.2.3.06 1.79 0.70 0.04 0.09 0.61 0.04 0.84 Alloy gray cast iron (SAE G4500) (2) 3.31 1.56 0.68 0.19 0.114 0.08 0.08 0.73 Gray cast iron SAE G4000 (2) 3.27 1.74 0.72 0.26 0.156 0.08 0.15 0.07 Ferritic malleable (3) (Cr
25、eep and stress rupture data)2.16 1.01 0.29 0.11 0.074 0.017 2.29 1.17 0.38 0.148 0.095 0.000Pearlitic malleable (3) 2.27 1.01 0.89 0.135 0.098 0.019 2.29 1.15 0.75 0.110 0.086 0.000Ferritic malleable (3) (Elevated temperature tensile strength data)2.30 0.98 0.30 0.162 0.078 2.33 1.05 0.34 0.168 0.08
26、4Gray cast iron SAE G4500 (4) 2.84 1.52 1.05 0.07 0.124 0.31 0.20 Ferritic ductile iron (4) 3.7 2.6 0.40 1.0 Low carbon steel (7) 0.08 0.25 0.30 0.045 0.060 0.20 0.80Austenitic ductile + Cr and Mo (9) 2.38 1.99 0.62 3.05 30.18 0.95 0.13Austenitic ductile + Cr (9) 2.98 2.20 1.15 2.36 20.48 0.085Ferri
27、tic ductile iron (4) 3.64 2.66 0.46 0.032 0.014 0.66 0.076Austenitic cast iron (17) 2.63 2.14 1.23 0.16 0.059 2.09 14.9 SAE J125 Reaffirmed MAY88-4-The material is stressed in tension under a constant load at a constant temperature and the time that it takesthe sample to rupture under these conditio
28、ns is recorded. Separate samples of the material are stressedunder a number of different loads at the same temperature and the rupture times are plotted against load togive a stress-rupture curve for the material. Typical stress-rupture curves for a number of SAE cast irons andalloyed irons at 800 F
29、 are plotted in Figure 2. Stress-rupture curves for these and other cast irons at 1000 Fare plotted in Figure 3, which includes a stress-rupture curve for low carbon wrought steel for comparison.FIGURE 2STRESS RUPTURE PROPERTIES OF CAST IRONS AT 800 FFIGURE 3STRESS RUPTURE PROPERTIES OF CAST IRONS A
30、T 1000 FSAE J125 Reaffirmed MAY88-5-4.3 Creep Properties of IronsAnother important temperature effect on cast irons is the effect of creep orelongation per hour at a given stress and temperature. These tests are difficult to run on cast irons because ofthe growth and oxidation phenomena. Figure 4 sh
31、ows typical creep curves for some SAE and alloyed castirons at 800 and 1000 F. A creep curve for a plain carbon steel at 1000 F is included for comparison. Thevalues shown on the creep rate curves in Figure 4 include any growth that occurred during the tests. Thisallows these figures to be used as d
32、esign parameters.FIGURE 4CREEP PROPERTIES OF CAST IRONS4.4 Growth of Cast IronGrowth in irons is generally defined as the permanent increase in volume which occursafter prolonged exposure to constant elevated temperatures or after repeated heating and cooling.The mechanism of growth is rather comple
33、x in irons owing to the fact that it results from several different andindependent phenomena; which phenomena occur in any given case is dependent upon the temperatureinvolved, the environment, the chemical composition and structure of the iron, and the severity of cycling, if any.The main phenomena
34、 which cause growth in irons at temperature are as follows:1. Oxidation: This may progress into the body of an iron along graphite flakes or cracks, resulting in agreater dimensional change than in materials where oxidation is limited to the surfaces.2. Graphitization: If the iron has carbides in it
35、s structure and is heated to a temperature which willdecompose the carbide structures (this temperature will vary considerably with chemistry), theresulting ferrite and graphite will occupy considerably greater volume than the original carbide.3. Crazing or Thermal Cracking: When an iron is repeated
36、ly heated and cooled through a transformationrange, the stresses, imposed by the expansion and contraction resulting from the transformation, willcause crazing.Ductile and malleable irons are less affected by oxidation than gray iron. Some investigators have indicatedthat this difference is a result
37、 of graphite carbon shapes. Alloyed irons are usually less susceptible to growth,and this can either be due to an increased stability of the structure at the temperature involved, improvedoxidation resistance, or a change of the critical temperature so the part does not experience a transformation i
38、nthe temperature range. Examples of the growth experienced by some common SAE irons are shown in Figure5.SAE J125 Reaffirmed MAY88-6-FIGURE 5CAST IRON GROWTH AT 1000 F4.5 Endurance LimitRelatively little data are available on the endurance limit of cast irons at elevatedtemperatures. The curves in F
39、igure 6 show the relationship between the tensile strength and the endurancelimit of a low carbon equivalent low alloy gray cast iron up to a temperature of 1100 F. It can be seen that theendurance ratio is nearly constant from room temperature to 1100 F for this iron. It is probable that for mostgr
40、ay cast irons heated in air, the endurance ratio would remain nearly constant up to a temperature at whichchanges occur in the structure or severe oxidation takes place. A second set of curves for an austenitic grayiron are included in Figure 6. This shows how the endurance limit is affected by stru
41、cture.FIGURE 6EFFECT OF TEMPERATURE ON STRENGTH AND ENDURANCE LIMITSAE J125 Reaffirmed MAY88-7-5. Effect of Temperature on Physical Properties5.1 Modulus of ElasticityThe modulus of elasticity at room temperature varies considerably for the varioustypes of iron. It is difficult to give representativ
42、e figures; but, in general, it can be said that the cast irons do notshow a marked drop in modulus up to 800 F.5.2 Specific Heatof ferritic malleable iron:The specific heat of pearlitic malleable iron is substantially the same as that of ferritic malleable.In gray cast iron the specific heat varies
43、with the temperature and the structure; therefore, a temperature rangewhich causes a change in microstructure may result in a reversal in the specific heat versus temperature curvewhich will result in a curve such as Figure 7. A commonly used figure for average cast irons is 0.13 cal/g-C.FIGURE 7SPE
44、CIFIC HEAT VERSUS TEMPERATURE FOR A GRAY CAST IRON (4)5.3 Thermal ConductivityThe thermal conductivity of gray cast iron varies considerably with both temperatureand composition. Most plain and alloy gray irons will have a thermal conductivity of 0.10 to 0.135 cal-cm/s-cm2-C at 100 C and this will d
45、rop to about 0.09-0.115 cal-cm/s-cm2C at 400 C. Some specific cases aregiven in the following table:Temperature Range Mean Specific HeatF C Btu/lb-F Cal/g-C70- 210 20-100 0.122 0.12270- 570 20-300 0.128 0.12870- 750 20-400 0.139 0.13970-1300 20-700 0.159 0.159SAE J125 Reaffirmed MAY88-8-Malleable ir
46、on has a thermal conductivity of about 0.151 cal-cm/s-cm2-C at 100 C (437.9 Btu-in/h-ft2-F at212 F) and 0.139 cal-cm/s-cm2-C at 400 C (403.1 Btu-in/h-ft2-F at 750 F).Ductile cast iron has the following conductivity.5.4 Average Coefficient of ExpansionThe coefficient of expansion of cast irons varies
47、 with temperature, andto a lesser degree with alloy content and structure or heat treatment. The following table gives valuescommonly used:6. Bibliography1. “Mechanical Properties of Metals and Alloys.“ U.S. Dept. of Commerce Circular C-447, NationalBureau of Standards, 1943.2. Kattus and McPherson,
48、 “Properties of Cast Iron at Elevated Temperatures.“ ASTM Special TechnicalPublication No. 248.3. Malleable Iron Casting Handbook. Malleable Founders Society, 1960.4. Gray Iron Castings Handbook. Gray Iron Founders Society, Inc., 1958.5. Cast Metals Handbook. American Foundrymens Society, 1957.6. Co
49、lin J. Smithell, “Metals Reference Book.“ Washington Butterworths, 1962.7. Metals Handbook, 8th Edition. American Society for Metals, 1961.Grade or Type Cal-cm/s-cm2-C Btu-in/h-ft2-FAt 100 C At 400 C at 212 C at 750 FSAE G4000 +Low S 0.135 0.114 391.5 330.6SAE G5000 0.110 0.100 319 290Mo alloyed (ASTM A 48, No. 55) 0.118 0.108 342.2 313.2Mo+Ni alloyed (ASTM A 48, No. 55) 0.106 0.097 307.4 281.3Type Cal-cm/s-cm2-C Btu-in/h-ft2-FAt 100 C At 400 C At 212 F At
