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.

SCM440 Forged round steel

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 GroupRepresent LettersSteel GroupRepresent Letters
Carbon steelSXXC,SXXCKChrome-molybdenum steelSCM
Manganese steelSMnNickel-chromium steelSNC
Manganese chrome steelSMnCNickel-chromium-molybdenum steelSNCM
Chrome steelSCrAluminum Chrome Molybdenum SteelSACM
Table 2
Alloy element content digital codeManganese steel Manganese chrome steel Chrome steel Chrome-molybdenum steel Nickel-chromium steel Nickel-chromium-molybdenum steel
MnMn CrCrCrMoNiCrNiCrMo
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 FormSize(mm)ProcessTolerance



Round
Φ6-Φ100Cold DrawnBright/Black Best H11

Φ16-Φ350

Hot Rolled
Black-0/+1mm
Peeled/ground Best H11

Φ90-Φ1000

Hot Forged
Black-0/+5mm
Rough Turned-0/+3mm

Flat/Square/Block
Thickness :120-800
Hot Forged
Black-0/+8mm
Width:120-1500
Rough Machined-0/+3mm

SCM440 | SCM430 STEEL CHEMICAL COMPOSITION

GradeCSiMnPSCrMo
SCM4400.38-0.430.15-0.350.6-0.85≤ 0.035≤ 0.040.9-1.20.15-0.30
SCM4300.28-0.33 0.15-0.35 0.6-0.85 ≤ 0.035≤ 0.040.9-1.2 0.15-0.30

SCM440 | SCM430 STEEL RELATED STANDARD & EQUIVALENT GRADE

SCM440SCM430
CHINA42CrMo30CrMo
USA4140/41424130
Europe42CrMo4/1.722525CrMo4/1.7218
UKEN19/708M40708M25

SCM440 | SCM430 STEEL FORGING

SCM440SCM430
Initial Forging Temperature1150℃1180℃
Final Forging Temperature850℃800℃
Forging Ratio≥4:1≥4:1
Post-Forging TreatmentSlow cooling in sandSlow cooling in sand

SCM440 | SCM430 STEEL HEAT TREATMENT

  • SCM440 | SCM430 Steel Normalizing & Annealing

SCM440SCM430
Normalizing Temperature850~900℃870~900℃
Cooling MethodAir CoolingAir Cooling
AnnealingTemperature850℃830-850℃
Cooling MethodFurnance CoolingFurnance Cooling
  • SCM440 | SCM430 Steel Quenching & Tempering
SCM440SCM430
QuenchingTemperature830~880℃830~880℃
Quenching mediumOil/WaterOil/Water
TemperingTemperature530-630℃530-630℃
Cooling MethodAir CoolingAir Cooling
Hardness241-302HB285-352HB

SCM440 | SCM430 Steel Mechanical Property with Quenched and Tempered Condition

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