SCM440/SCM430 steel Manufacturer and Exporter,supplied with round,square,flat,block,and shaft etc.

SCM440/SCM430 steel beglongs to Japanese standard JIS G4105.As two representative steel grades of chrome molybdenum steel,they play roles equivalent to American grades AISI 4140 and 4130, and European grades 42CrMo4 and 25CrMo4.

SCM440/SCM430 steel belongs to medium hardenability steel with good comprehensive mechanical properties after heat treatment, such as good strength and plasticity, and good impact properties.They are usually delivered in a quenched and tempered condition.

WHAT DOES SCM440/SCM430 MEAN?

SCM440 and SCM430 steel, we all know that they are both Japanese grades and belong to structural steel for machinery manufacturing, so what is the meaning of their alphanumerics?

According to JIS (Janpanese Industrial Standard),alloy structural steel consists of the following parts.

S O O O X X X O

S –Steel

OOO–Major alloying element symbols（For details, see Table 1)

X–Digital code of main alloying element content（For details, see Table 2)

XX–Average carbon content，Wc%x100

O–Suffix notation

Table 1
Steel Group	Represent Letters	Steel Group	Represent Letters
Carbon steel	SXXC,SXXCK	Chrome-molybdenum steel	SCM
Manganese steel	SMn	Nickel-chromium steel	SNC
Manganese chrome steel	SMnC	Nickel-chromium-molybdenum steel	SNCM
Chrome steel	SCr	Aluminum Chrome Molybdenum Steel	SACM

Table 2
Alloy element content digital code	Manganese steel	Manganese chrome steel		Chrome steel	Chrome-molybdenum steel		Nickel-chromium steel		Nickel-chromium-molybdenum steel
Alloy element content digital code	Mn	Mn	Cr	Cr	Cr	Mo	Ni	Cr	Ni	Cr	Mo
2	>1.0 <1.3	>1.0 <1.3	>0.3 <0.9	>0.3 <0.8	>0.3 <0.8	>0.15 <0.30	>1.0 <2.0	>0.25 <1.25	>0.2 <0.7	>0.2 <1.0	>0.15 <0.40
4	>1.3 <1.6	>1.3 <1.6	>0.3 <0.9	>0.8 <1.4	>0.8 <1.4	>0.15 <0.30	>2.0 <2.5	>0.25 <1.25	>0.7 <2.0	>0.4 <1.5	>0.15 <0.40
6	>1.6	>1.6	>0.3 <0.9	>1.4 <2.0	>1.4	>0.15 <0.30	>2.5 <3.0	>0.25 <1.25	>2.0 <3.5	>1.0	>0.15 <1.0
8	-	-	-	-	>0.8 <1.4	>0.3 <0.6	>3.0	>0.25 <1.25	>3.5	>0.7 <1.5	>0.15 <0.40

I believe that here, you can basically understand the hidden meanings of the numbers and letters in the SCM440 and SCM430 grades.

SCM440 | SCM430 STEEL SUPPLY FORM & SIZE & TOLERANCE

Supply Form	Size(mm)	Process	Tolerance
Round	Φ6-Φ100	Cold Drawn	Bright/Black	Best H11
	Φ16-Φ350	Hot Rolled	Black	-0/+1mm
	Φ16-Φ350	Hot Rolled	Peeled/ground	Best H11
	Φ90-Φ1000	Hot Forged	Black	-0/+5mm
	Φ90-Φ1000	Hot Forged	Rough Turned	-0/+3mm
Flat/Square/Block	Thickness :120-800	Hot Forged	Black	-0/+8mm
Flat/Square/Block	Width:120-1500	Hot Forged	Rough Machined	-0/+3mm

SCM440 | SCM430 STEEL CHEMICAL COMPOSITION

Grade	C	Si	Mn	P	S	Cr	Mo
SCM440	0.38-0.43	0.15-0.35	0.6-0.85	≤ 0.035	≤ 0.04	0.9-1.2	0.15-0.30
SCM430	0.28-0.33	0.15-0.35	0.6-0.85	≤ 0.035	≤ 0.04	0.9-1.2	0.15-0.30

SCM440 | SCM430 STEEL RELATED STANDARD & EQUIVALENT GRADE

	SCM440	SCM430
CHINA	42CrMo	30CrMo
USA	4140/4142	4130
Europe	42CrMo4/1.7225	25CrMo4/1.7218
UK	EN19/708M40	708M25

SCM440 | SCM430 STEEL FORGING

	SCM440	SCM430
Initial Forging Temperature	1150℃	1180℃
Final Forging Temperature	850℃	800℃
Forging Ratio	≥4:1	≥4:1
Post-Forging Treatment	Slow cooling in sand	Slow cooling in sand

SCM440 | SCM430 STEEL HEAT TREATMENT

SCM440 | SCM430 Steel Normalizing & Annealing

	SCM440	SCM430
Normalizing Temperature	850~900℃	870~900℃
Cooling Method	Air Cooling	Air Cooling
AnnealingTemperature	850℃	830-850℃
Cooling Method	Furnance Cooling	Furnance Cooling

SCM440 | SCM430 Steel Quenching & Tempering

	SCM440	SCM430
QuenchingTemperature	830~880℃	830~880℃
Quenching medium	Oil/Water	Oil/Water
TemperingTemperature	530-630℃	530-630℃
Cooling Method	Air Cooling	Air Cooling
Hardness	241-302HB	285-352HB

SCM440 | SCM430 Steel Mechanical Property with Quenched and Tempered Condition

Grade	Tensile Strength	Yield Strength	Elongation	Reduction of Area	Impact Charpy-V
SCM440	>981Mpa	>834Mpa	>12%	>45%	>59 J/cm2
SCM430	>834Mpa	>686Mpa	>15%	>55%	>108 J/cm2