Table 3 CrMo steels for machine structural use (Excerpted from
JIS G 40532003 and supplemented with AISI/SAE)
JISgrade(AISI/SAE)*4Chemical composition(%)Tensile
testBrinellhardnessHeat
treatment()Carbon*2equivalentWeldability*3
CSiMnCrMoTensilestrength(MPa)Elongation(%)QuenchingTempering
SCM415()0.13~0.180.15~0.350.60~0.900.90~1.200.15~0.2583016235~3211st
850~900Oil cooling2nd 800~850Oil cooling150~200Aircooling0.56
SCM418()0.16~0.210.15~0.350.60~0.900.90~1.200.15~0.2588015248~3311st
850~900Oil cooling2nd 800~850Oil cooling150~200Aircooling0.59
SCM420()0.18~0.230.15~0.350.60~0.900.90~1.200.15~0.2593014262~3521st
850~900Oil cooling2nd 800~850Oil cooling150~200Aircooling0.61
SCM421()0.17~0.230.15~0.350.70~1.000.90~1.200.15~0.2598014285~3751st
850~900Oil cooling2nd 800~850Oil cooling150~200Aircooling0.62
SCM430(4130)0.28~0.330.15~0.350.60~0.900.90~1.200.15~0.3083018241~302830~880Oil
cooling550~650Rapidcooling0.71
SCM432()0.27~0.370.15~0.350.30~0.601.00~1.500.15~0.3088016255~321830~880Oil
cooling550~650Rapidcooling0.71
SCM435(4137)0.33~0.380.15~0.350.60~0.900.90~1.200.15~0.3093015269~331830~880Oil
cooling550~650Rapidcooling0.76
SCM440(4140,4142)0.38~0.430.15~0.350.60~0.900.90~1.200.15~0.3098012285~352830~880Oil
cooling550~650Rapidcooling0.81
SCM445(4145,4147)0.43~0.480.15~0.350.60~0.900.90~1.200.15~0.30103012302~363830~880Oil
cooling550~650Rapidcooling0.86
SCM822()0.20~0.250.15~0.350.60~0.900.90~1.200.35~0.45103012302~4151st
850~900Oil cooling2nd 800~850Oil cooling150~200Aircooling0.68
