JIS G4105 4130 Tubing
Japanese drawings call chromium-molybdenum steel SCM, and the grade closest to 4130 is SCM430. JIS G4105 was the standard that originally listed it.
SCM430 and 4130 — Comparison
SCM430 (JIS G4105) and AISI 4130 (ASTM A519) are close equivalents but are not automatically interchangeable without a formal engineering comparison. The carbon, chromium, and molybdenum limits in JIS G4105 and ASTM A519/A29 are similar but not identical. For procurement where the drawing specifies JIS G4105 SCM430, the substitution of AISI 4130 requires engineering review.
| Designation System | Grade | Standard |
|---|---|---|
| JIS (Japan) | SCM430 | JIS G4105 |
| AISI/SAE (North America) | 4130 | ASTM A519 (tube) / A29 (bar) |
| EN (Europe) | 25CrMo4 | EN 10297 (tube) / EN 10083 (steel) |
| UNS | G41300 | Cross-reference |
| Substitution | Requires formal engineering comparison | Not automatic |
Understanding the SCM430 Designation
In the JIS system, S stands for steel, C for chromium and M for molybdenum. The number that follows identifies the grade, with the last two digits indicating carbon: SCM430 has about 0.30 percent carbon, SCM435 about 0.35 percent and SCM440 about 0.40 percent. The pattern mirrors the American 4130, 4135 and 4140.
JIS G4105 has since been withdrawn and its grades moved into a consolidated standard for alloy steels for machine structural use, so current Japanese documents may quote a different standard number for the same SCM430 grade. Tube for machine structural purposes is covered by a separate JIS tube standard, where the grade carries a TK suffix.
If a Japanese drawing requires SCM430 and you intend to supply 4130, compare the composition limits and obtain approval for the substitution, as you would for any equivalent. The chemistry ranges for 4130 are given under chemical composition; other equivalents are listed under 4130 equivalent material.
Frequently Asked Questions
Can I supply AISI 4130 against a JIS G4105 SCM430 requirement?
A substitution requires a formal comparison of the composition limits in JIS G4105 (SCM430) and ASTM A519 (Grade 4130) for the specific heat supplied. If the actual ladle analysis falls within both sets of limits, the substitution may be approved by the responsible engineer. This must be documented and approved — it cannot be assumed.
What does SCM stand for?
Steel, chromium, molybdenum in the JIS designation system.
Which JIS grade corresponds to 4130?
SCM430 is the closest equivalent.
Is JIS G4105 still in force?
No. Its grades were transferred to a consolidated JIS standard for alloy steels for machine structural use.
What does the TK suffix mean on a JIS tube grade?
It identifies tube for machine structural purposes.
Are SCM430 and 4130 identical?
They are close equivalents with similar carbon, chromium and molybdenum, but their limits are not identical.
JIS G4105 / 4130 Procurement Enquiry
Specify your JIS standard, grade, and whether an AISI equivalent is acceptable to receive a relevant quotation.
- JIS G4105 SCM430 or AISI 4130 equivalent
- Product form (tube or bar)
- OD & Wall or diameter
- Condition
- MTC requirement
- Delivery