Steel SCMn5
JIS SCMn5
SCMn5 is the highest-strength manganese steel casting grade in the JIS G5111 SCMn series, offered as-cast, annealed, normalized, NT, quenched and tempered plus a higher-hardness Q&T class, and stress relieved.
Reference datasheet — SCMn5 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT condition
SCMn5 tempers and conditions
SCMn5 is supplied in 7 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition, chosen when heavy rough machining or maximum dimensional stability precedes final hardening. | 330 | 600 | 22 | 175 HB | — |
As fabricated | Foundry-raw condition only used for rough handling before heat treatment; does not meet JIS G 5111 mechanical requirements. | 360 | 640 | 10 | 12 HRC | 7.8 % IACS |
Normalized | Grain-refining normalize only; used for large or complex castings where quenching would crack or distort. | 420 | 700 | 15 | 16 HRC | 7.8 % IACS |
Normalized and tempered | Standard JIS delivery condition for thick-section SCMn5 castings that still must reach 690 MPa with reasonable toughness. | 470 | 730 | 17 | 215 HB | — |
Stress relieved | Applied after weld repair or heavy machining of an already heat-treated casting to remove residual stress with minimal property loss. | 495 | 750 | 17 | 20 HRC | 7.8 % IACS |
QTDefault Quenched and tempered | Most commonly supplied condition — highest strength/wear resistance combination for gearbox housings, crusher and rail castings. | 520 | 780 | 16 | 22 HRC | — |
Quenched and low-temperature tempered | Non-standard high-hardness variant ordered when abrasion resistance outweighs impact toughness (liners, wear plates). | 680 | 920 | 11 | 30 HRC | — |
What is SCMn5?
SCMn5 is the highest-strength manganese steel casting grade in the JIS G5111 SCMn series, offered as-cast, annealed, normalized, NT, quenched and tempered plus a higher-hardness Q&T class, and stress relieved. It is used for heavy gears, wheels and high-load structural castings, providing 520 MPa yield, 780 MPa tensile, 16 % elongation and 235 HB (22 HRC) in the default condition. Machinability and weldability both rate 45, the carbon equivalent of 0.6–0.7 requires preheat and stress relief, and the 400 °C limit with no corrosion resistance makes coatings mandatory. SCMn3 is the more weldable step down. SCMn5 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). SCMn5 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 67% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
What is SCMn5 used for?
- Heavy gears
- Wheels
- High-load structural castings
Limitations
- Limited formability — 15/100, worse than 87% of steel grades
- Low fracture toughness — 65 MPa·√m (59.2 ksi·√in), worse than 75% of steel grades
SCMn5 properties
Typical room-temperature values for SCMn5-QT; bars are the position among steel grades.
Physical3
SCMn5 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
SCMn5 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 67% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SCMn5 is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
SCMn5 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SCMn5 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 75%.
Manufacturability8
SCMn5's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (45/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. SCMn5 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SCMn5
Is SCMn5 easy to machine?
Machine in the annealed or normalized state where possible; in Q&T (≈235 HB) use rigid setups, coated carbide at ~120–180 m/min and expect hard skin/scale on unblasted cast surfaces.
Can SCMn5 be welded?
Carbon equivalent ~0.6–0.7: use low-hydrogen consumables, 150–250 °C preheat, controlled interpass and 580–650 °C post-weld stress relief to avoid HAZ cracking.
Can SCMn5 be formed, bent or molded?
Sand or shell cast with generous risering — Mn steel has moderate fluidity and appreciable solidification shrinkage (~2 %); avoid abrupt section changes and always heat treat after casting.
SCMn5 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CJIS G 5111 SCMn5 | 0.3 – 0.4 | 0.35 |
| Sitypically ≤0.80 max in some producer specs | 0.3 – 0.6 | 0.45 |
| Mn | 1.2 – 1.6 | 1.4 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Niresidual | ≤ 0.3 | |
| Crresidual | ≤ 0.3 | |
| Moresidual | ≤ 0.15 | |
| Curesidual | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SCMn5?
No natural corrosion resistance — shot blast to SA 2.5 then paint, zinc-rich primer, phosphate or hard chrome/thermal spray on wear faces; not anodizable.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
How much does SCMn5 cost?
SCMn5 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SCMn5 — frequently asked
What is SCMn5 used for?
SCMn5 is typically used for heavy gears, wheels and high-load structural castings. In short: strongest SCMn casting grade; wear-resistant Mn steel casting; requires preheat for welding.
What is the yield strength of SCMn5?
SCMn5 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SCMn5 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed or normalized state where possible; in Q&T (≈235 HB) use rigid setups, coated carbide at ~120–180 m/min and expect hard skin/scale on unblasted cast surfaces.
Can SCMn5 be welded?
With care — weldability is rated fair (45/100). Carbon equivalent ~0.6–0.7: use low-hydrogen consumables, 150–250 °C preheat, controlled interpass and 580–650 °C post-weld stress relief to avoid HAZ cracking.
What surface finishes work on SCMn5?
No natural corrosion resistance — shot blast to SA 2.5 then paint, zinc-rich primer, phosphate or hard chrome/thermal spray on wear faces; not anodizable.
Can SCMn5 be formed, bent or molded?
Sand or shell cast with generous risering — Mn steel has moderate fluidity and appreciable solidification shrinkage (~2 %); avoid abrupt section changes and always heat treat after casting.
What is the maximum service temperature of SCMn5?
SCMn5 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SCMn5-QT and SCMn5-A?
QT is the default condition — most commonly supplied condition — highest strength/wear resistance combination for gearbox housings, crusher and rail castings. A: softest condition, chosen when heavy rough machining or maximum dimensional stability precedes final hardening. Yield strength is 520 MPa in QT versus 330 MPa in A.
How much does SCMn5 cost?
SCMn5 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- JIS G 5111 — High tensile strength carbon steel castings and low alloy steel castings for structural purposes — JSA (2019)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Steel Castings) — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- GB/T 14408 / GB/T 11352 — (ZG30Mn analogue) — SAC (2009)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.