Steel SCMn3-SR (Stress relieved)
Heat-treated state
JIS SCMn3
Sub-critical soak (550–650 °C) to remove casting/welding residual stress with minimal change to mechanical properties.
Values for the SR condition
Other SCMn3 tempers and conditions
SCMn3 is listed in 7 conditions; see the grade overview at SCMn3.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose when maximum machinability and dimensional stability matter more than strength, or before further heat treatment. | 320 | 580 | 22 | 170 HB | — |
As fabricated | Only for non-critical parts or as an intermediate state before heat treatment; coarse dendritic structure and low toughness. | 340 | 620 | 10 | 195 HB | 8 % IACS |
Normalized | Refines the as-cast grain and gives uniform properties at low cost; used where the tempered condition is not required. | 420 | 700 | 16 | 210 HB | 8 % IACS |
SRThis page Stress relieved | Sub-critical soak (550–650 °C) to remove casting/welding residual stress with minimal change to mechanical properties. | 420 | 680 | 17 | 200 HB | 8 % IACS |
N+TDefault Normalized and tempered | Default supply condition: meets the JIS G5111 SCMn3 minima (640 MPa UTS / 370 MPa YS / 13 % elongation) with balanced toughness in medium sections. | 430 | 690 | 17 | 205 HB | — |
Quenched and tempered | Pick for the highest strength and best toughness combination in sections up to ~100 mm — gears, links, heavy machine frames. | 620 | 830 | 15 | 25 HRC | — |
Quenched and tempered to a specified hardness band | Ordered when a hardness window is contractually required (wear surfaces, induction-hardened bases, gear blanks). | 760 | 950 | 13 | 30 HRC | — |
What is SCMn3-SR?
SCMn3-SR is SCMn3 heat treated to SR — sub-critical soak (550–650 °C) to remove casting/welding residual stress with minimal change to mechanical properties. SCMn3-SR has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 53% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi). SCMn3-SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). N+T is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Limited formability — 15/100, worse than 87% of steel grades
SCMn3-SR properties
Typical room-temperature values for SCMn3-SR; 22 are specific to this condition. Other listed values are SCMn3 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SCMn3-SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
SCMn3-SR has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 53% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SCMn3-SR 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 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
SCMn3-SR conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SCMn3-SR takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 85%.
Manufacturability8
SCMn3-SR's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (50/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SCMn3-SR
Is SCMn3 easy to machine?
Machines like a medium-carbon alloy steel (~55 % of 1212); rough-cut after normalizing, finish after final tempering, and expect abrasive skin/sand inclusions on unblasted surfaces.
Can SCMn3 be welded?
Weldable with low-hydrogen E7018/ER80S consumables but CE ≈ 0.6–0.7 — preheat 200–300 °C, control interpass, and stress-relieve or re-normalize/temper after major repair welds.
Can SCMn3 be formed, bent or molded?
Sand or shell cast with generous risering (solidification shrinkage ~5 %); avoid abrupt section changes and always heat treat to break up the coarse as-cast dendritic structure.
What surface finishes work on SCMn3?
No anodizing; shot-blast then phosphate + epoxy/zinc-rich paint, or zinc/hard-chrome plate wear faces — bare surfaces rust rapidly outdoors.
SCMn3 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 |
|---|---|---|
| Cdistinguishes SCMn3 from SCMn1/SCMn2/SCMn5 | 0.3 – 0.4 | 0.35 |
| Sideoxidation; upper limit per JIS G5111 | 0.3 – 0.8 | 0.5 |
| Mn | 1 – 1.6 | 1.35 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Febalance, incidental residuals (Cu, Ni, Cr, Mo) restricted by agreement | balance | — |
SCMn3-SR — frequently asked
What is SCMn3-SR used for?
SCMn3-SR is typically used for gear housings, heavy equipment brackets and structural castings. In short: mid-range SCMn strength; balanced strength and cost; heat-treatable Mn casting.
What is the yield strength of SCMn3-SR?
SCMn3-SR has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SCMn3-SR easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machines like a medium-carbon alloy steel (~55 % of 1212); rough-cut after normalizing, finish after final tempering, and expect abrasive skin/sand inclusions on unblasted surfaces.
Can SCMn3-SR be welded?
With care — weldability is rated fair (50/100). Weldable with low-hydrogen E7018/ER80S consumables but CE ≈ 0.6–0.7 — preheat 200–300 °C, control interpass, and stress-relieve or re-normalize/temper after major repair welds.
What surface finishes work on SCMn3-SR?
No anodizing; shot-blast then phosphate + epoxy/zinc-rich paint, or zinc/hard-chrome plate wear faces — bare surfaces rust rapidly outdoors.
Can SCMn3-SR be formed, bent or molded?
Sand or shell cast with generous risering (solidification shrinkage ~5 %); avoid abrupt section changes and always heat treat to break up the coarse as-cast dendritic structure.
What is the maximum service temperature of SCMn3-SR?
SCMn3-SR 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 SCMn3 N+T and SCMn3-A?
N+T is the default condition — default supply condition: meets the JIS G5111 SCMn3 minima (640 MPa UTS / 370 MPa YS / 13 % elongation) with balanced toughness in medium sections. A: choose when maximum machinability and dimensional stability matter more than strength, or before further heat treatment. Yield strength is 430 MPa in N+T versus 320 MPa in A.
Sources
- JIS G 5111 — Steel castings for structural, high-strength and low-alloy service — Japanese Standards Association (2019)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- GB/T 14408 / GB/T 11352 (comparable Chinese cast-steel grades, e.g. ZG35Mn) — SAC (2014)
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.