SUS410 (JIS G4303) is the base hardenable martensitic stainless steel — 11.5–13.5% Cr with enough carbon (0.08–0.15%) to form martensite on quenching. Unlike the austenitic 300-series grades, SUS410 is magnetic, can be hardened to 35–45HRC by heat treatment, and has moderate corrosion resistance suited to mild environments. The practical choice for valves, pump internals, turbine blades, cutlery blanks, and general-purpose corrosion-resistant components where wear resistance or hardness matters more than the superior corrosion performance of SUS304. This guide covers the heat treatment conditions, the corrosion limits engineers often underestimate, and the two grades (SUS420J2 and SUS431) that replace SUS410 when hardness or corrosion requirements are higher.
- International Equivalent Grades
- Chemical Composition
- Mechanical Properties by Heat Treatment Condition
- Heat Treatment
- Corrosion Resistance
- Machinability & Weldability
- Common Mistakes
- When to Choose SUS410
- FAQ
1. International Equivalent Grades
| Standard | Grade | Region | Match Type |
|---|---|---|---|
| JIS G4303 | SUS410 | Japan | Reference |
| ASTM A276 / A582 | AISI 410 / Type 410 | USA | ✅ Nearest Exact |
| EN 10088-1 | 1.4006 / X12Cr13 | Europe | ✅ Nearest Exact |
| DIN 17440 | X12Cr13 | Germany | ✅ Nearest Exact |
| ISO 15510 | X12Cr13 | International | ✅ Nearest Exact |
| GB/T 4237 | 12Cr13 | China | ✅ Nearest Exact |
2. Chemical Composition
| Element | SUS410 (JIS G4303) | AISI 410 (ASTM) | 1.4006 (EN 10088-1) |
|---|---|---|---|
| C | 0.08–0.15% | ≤ 0.15% | 0.08–0.15% |
| Si | ≤ 1.00% | ≤ 1.00% | ≤ 1.00% |
| Mn | ≤ 1.00% | ≤ 1.00% | ≤ 1.50% |
| Cr | 11.50–13.50% | 11.50–13.50% | 11.50–13.50% |
| Ni | ≤ 0.60% | — | ≤ 1.00% |
| Mo | — | — | — |
Source: JIS G4303:2012, ASTM A276/A276M-17, EN 10088-1:2014. The 0.08–0.15% C range is the key: high enough to form martensite on quenching, low enough to maintain reasonable toughness and corrosion resistance after tempering.
3. Mechanical Properties by Heat Treatment Condition
SUS410’s properties vary widely depending on heat treatment. Annealed material is soft and machinable; hardened and tempered material provides the wear/strength performance the grade is selected for.
| Condition | Tensile Strength | 0.2% Proof Stress | Elongation | Hardness |
|---|---|---|---|---|
| Annealed | ≥ 440 MPa (64 ksi) | ≥ 205 MPa (30 ksi) | ≥ 20% | ≤ 200HBW |
| Hardened (as-quenched) | ~1200–1400 MPa | — | ~8–12% | ~45–50HRC |
| H+T (200°C temper) | ~1100–1300 MPa (160–190 ksi) | ~900 MPa (130 ksi) | ~10% | 38–44HRC |
| H+T (600°C temper) | ~760–900 MPa (110–130 ksi) | ~590 MPa (86 ksi) | ≥ 20% | 22–28HRC |
| H+T (700°C temper) | ~550–700 MPa (80–100 ksi) | ~380 MPa (55 ksi) | ≥ 25% | 16–22HRC |
4. Heat Treatment
Annealing
Heat to 750–900°C (1382–1652°F), hold for uniform temperature, then furnace cool or air cool. Produces the soft, machinable condition. Sub-critical anneal (730–760°C) is used after cold working to restore ductility without full recrystallization.
Hardening (Austenitizing + Quench)
Heat to 950–1050°C (1742–1922°F), hold to dissolve carbides, then quench in oil or air. Air cooling is often sufficient for thin sections — SUS410 has moderate hardenability. As-quenched hardness reaches ~45–50HRC but the material is brittle and must be tempered immediately.
Tempering
| Tempering Range | Resulting Hardness | Typical Application |
|---|---|---|
| 150–200°C (302–392°F) | 40–44HRC | Cutlery blades, wear-resistant components |
| 550–650°C (1022–1202°F) | 22–28HRC | Valves, pump shafts, general engineering |
| 650–750°C (1202–1382°F) | 16–22HRC | Maximum toughness, pressure vessel applications |
5. Corrosion Resistance
SUS410’s 12% Cr provides basic stainless behavior — it will not rust in dry indoor environments and resists mild atmospheric exposure. However, with no Ni and no Mo, its PREN is approximately 11–13, significantly below the 300-series grades.
| Environment | SUS410 | SUS304 | Notes |
|---|---|---|---|
| Indoor, dry | ✅ Adequate | ✅ Adequate | 410 sufficient |
| Mild atmospheric (urban/rural) | ⚠️ Light staining possible | ✅ Adequate | 410 requires periodic maintenance |
| Outdoor coastal | ❌ | ⚠️ Marginal | 316 minimum |
| Freshwater | ⚠️ Marginal | ✅ Adequate | Depends on temperature and pH |
| Dilute acids | ❌ | ⚠️ Limited | Neither suitable without testing |
| Steam / condensate | ✅ Adequate (tempered) | ✅ Adequate | 410 used for steam valves and turbine blades |
6. Machinability & Weldability
Machinability
In the annealed condition, SUS410 machines at approximately 60–70% of AISI 1212 free-machining carbon steel — better than austenitic grades (SUS304 ~50%) due to the absence of work-hardening tendency. In the hardened and tempered condition, machinability decreases significantly; most SUS410 parts are machined in the annealed state and then heat-treated.
Weldability
SUS410 is weldable but requires care: the HAZ becomes hard and brittle due to martensite formation. Preheat to 200–300°C (392–572°F) for sections over 6 mm, and post-weld temper immediately after cooling to minimize cracking risk. Recommended filler: ER410 (matching) or ER309 (austenitic buffer for dissimilar joints). Welded joints in the as-welded condition have significantly reduced toughness — post-weld heat treatment is mandatory for structural applications.
7. Common Mistakes
8. When to Choose SUS410
Hardness or wear resistance is needed alongside basic stainless behavior: valves, pump internals, turbine blades, fasteners in steam service, cutlery grade steel (before higher-C grades are needed). Mildly corrosive environments — steam, freshwater, mild atmospheric — where the 300-series’ higher corrosion resistance is unnecessary.
Higher hardness is required: blade cutting edges, mold cavities, surgical instruments. SUS420J2 (C 0.26–0.40%) hardens to 50–56HRC versus SUS410’s 45HRC maximum. The trade-off is slightly lower corrosion resistance.
Corrosion resistance is the primary requirement and hardness is secondary. For food processing, chemical equipment, and outdoor applications, the austenitic grades’ higher PREN and better weldability outweigh any advantage from SUS410’s heat-treatability.
9. FAQ
Q: Is SUS410 the same as AISI 410?
Yes. JIS G4303 SUS410 and ASTM A276 Type 410 share the same 11.5–13.5% Cr and 0.08–0.15% C composition limits. Mill certificates from either standard are acceptable for most engineering applications.
Q: What hardness can SUS410 reach?
After hardening (950–1050°C, oil or air quench) and low-temperature tempering (150–200°C), SUS410 reaches approximately 40–44HRC. As-quenched hardness is ~45–50HRC, but the material is too brittle for use without tempering. Higher hardness requires SUS420J2 (up to 56HRC).
Q: Is SUS410 magnetic?
Yes — SUS410 is martensitic and strongly ferromagnetic in all heat treatment conditions. Unlike austenitic SUS304, there is no non-magnetic condition.
Q: Can SUS410 replace SUS304 in corrosive environments?
No. SUS410’s PREN (~12) is significantly below SUS304’s (~20). In environments where SUS304 is specified for corrosion resistance — outdoor, chloride, acidic media — SUS410 would corrode more rapidly. The substitution runs in the other direction: SUS410 can replace SUS304 in mild environments where hardness justifies it.
Summary
- SUS410 = AISI 410 = EN 1.4006: 12% Cr martensitic stainless, hardenable to 44HRC
- Magnetic in all conditions; hardened by conventional quench-and-temper heat treatment
- Corrosion resistance is modest (PREN ~12) — suitable for mild environments, steam, freshwater; not for chloride or outdoor coastal use
- Preheat (200–300°C) and post-weld temper are mandatory for structural welds — procedures differ significantly from austenitic grades
- Temper embrittlement zone: avoid 400–600°C tempering range
- Step up to SUS420J2 for higher hardness; step up to SUS304/316 for higher corrosion resistance
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