Steel SCMn5-NT (Normalized and tempered)
Heat-treated state
JIS SCMn5
Standard JIS delivery condition for thick-section SCMn5 castings that still must reach 690 MPa with reasonable toughness.
Values for the NT condition
Other SCMn5 tempers and conditions
SCMn5 is listed in 7 conditions; see the grade overview at SCMn5.
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 |
NTThis page 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-NT?
SCMn5-NT is SCMn5 heat treated to NT — standard JIS delivery condition for thick-section SCMn5 castings that still must reach 690 MPa with reasonable toughness. SCMn5-NT has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 57% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi). SCMn5-NT 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). QT is the default condition FabDigit quotes; NT is available on request or by drawing note.
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-NT properties
Typical room-temperature values for SCMn5-NT; 10 are specific to this condition. Other listed values are SCMn5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SCMn5-NT 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-NT has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 57% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SCMn5-NT 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-NT 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-NT 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-NT's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (45/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SCMn5-NT
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.
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.
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 | — |
SCMn5-NT — frequently asked
What is SCMn5-NT used for?
SCMn5-NT 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-NT?
SCMn5-NT has a typical yield strength of 470 MPa (68.2 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 57% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SCMn5-NT 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-NT 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-NT?
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-NT 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-NT?
SCMn5-NT 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.