# # SAE8620 Carburized Case+Core composite Surface HRc=58 # MacSteel Ht.:1M35594 ElecFurnace, RotaryCast, HotRolled to 25.4mm bar # Specimens were machined, Carburized, then ground and polished. # Hardness gradient: Rc=58 on surface, decreases to Rc=45 0.04 inch below # surface, then about Rc=46 for most of core. Eff Case 0.022" # Chem.: 0.20wt%C .96Mn .008P .030S .24Si .15Cu .53Ni # .55Cr .22Mo 0Ca .007Sn 88ppm_Ni # Inclusions: type A= 1 to 1.5, Type B,C,D=0 # ASTM grain size 5-6, martensite structure. Inclusions: TypeA=1-1.5Thin # Note: Subsurface fisheye failures observed. See fatigue report. # Test: UoToledo, F.Yin and A.Fatemi, Aug.2004 #FileType= strain_life #DataType= raw #Name= SAE8620 #Name= Case+Core #Name= AisiIt_70 #Stress_units= MPa #Strain_units= strain #Sy= 1401.7 #Su= 1677.2 #eu= 0.03 strain at Su, variable.See plot. #E= 207800 avg. of 12 #monotonic_K= 2524.1 #monotonic_n= 0.092 #FractureStrain= .153 #FractureStress= 1852. #%RA= 14.2 #%Elongation= 10.7 over 0.3" gauge #MaterialForm= bar #FailureDef= 50% load drop #BHN= 615 from surface HRc=58 #Some Init.Modulus below are average Emod #StrAmp 2Nf StsAmp So CalcPlasStr InitialModulus 0.0200 2 1798 -40.9 0.01131 211000 #IGL 0.0200 8 1694 -36.4 0.01179 200000 #IGL 0.0150 38 1546 -32.4 0.00748 208000 #IGL 0.0100 414 1284 56.0 0.00378 207800 #IGL #avg.Emod 0.0100 522 1286 -21.0 0.00378 210000 #IGL 0.0099 722 1309 -24.2 0.00360 207000 #IGL 0.0065 6986 1112 -2.9 0.00107 210000 #IGL 0.0065 7378 1096 37.6 0.00119 207800 #IGL #avg.Emod 0.0065 9424 1123 -18.0 0.00103 207000 #IGL 0.0050 25162 993 44.5 0.00018 210000 #IGL 0.0050 28156 987 77.9 0.00021 207000 #IGL 0.00500 33390 979 67.0 0.00026 208000 #IGL 0.00400 223310 837 3.3 0.00000 207800 #fisheye #avg.Emod 0.00400 236506 836 3.3 0.00000 207800 #IGL #avg.Emod 0.00400 400498 837 49.7 0.00000 208000 #fisheye 0.00325 9922112 669 5.6 0.00000 207600 #fisheye #avg.Emod 0.00325 10000000 672 0.0 0.00000 207800 #Runout 0.00325 10000000 672 0.0 0.00000 207800 #Runout #Electric Furnace= True #Continuous Cast= True #ASTM Grain Size No. (Min to Max)= 5 to 6 #Carbon, %= 0.2 #Manganese, %= 0.96 #Phosphorus, %= 0.008 #Sulfur, %= 0.3 Typo in database. 0.030S in report #Silicon, %= 0.24 #Copper, %= 0.15 #Nickel, %= 0.53 #Chromium, %= 0.55 #Molybdenum, %= 0.22 #Calcium, %= 0.00 #Tin, %= 0.007 #Nitrogen, ppm= 88 # #