Martensitic stainless steels (MSS) are a specialized class of stainless alloys engineered for high strength, hardness, and wear resistance while maintaining moderate corrosion resistance. These steels achieve their properties through heat treatment, typically involving quenching and tempering, and are widely used in applications requiring cutting tools, bearings, and structural components under demanding conditions.
Fundamentals of Martensitic Stainless Steels
Martensitic stainless steels (MSS) are a specialized class of stainless alloys renowned for their high strength, hardness, and wear resistance, achieved through heat treatment (quenching and tempering). These steels combine moderate corrosion resistance with exceptional mechanical properties, making them ideal for cutting tools, bearings, surgical instruments, and structural components in demanding environments.
Chemical Composition of Martensitic Stainless Steel
| Grade | Carbon (C) % | Chromium (Cr) % | Nickel (Ni) % | Molybdenum (Mo) % | Other Elements |
|---|---|---|---|---|---|
| 410 (UNS S41000) | 0.08–0.15 | 11.5–13.5 | ≤0.75 | — | Mn ≤ 1.0, Si ≤ 1.0 |
| 420 (UNS S42000) | 0.15–0.40 | 12.0–14.0 | ≤0.60 | — | Mn ≤ 1.0, Si ≤ 1.0 |
| 440C (UNS S44004) | 0.95–1.20 | 16.0–18.0 | ≤0.60 | ≤0.80 | Nb/Ti ≤ 0.10 |
| UGINOX MA4 | 0.10–0.15 | 12.5–14.0 | 0.6–1.0 | — | Al: 0.01–0.03 |
Physical Properties of Staninless Steel
| Property | 410 (Annealed) | 420 (Quenched & Tempered, HRC 50) | 440C (Quenched & Tempered, HRC 60) | UGINOX MA4 (Aged, 250°C) |
|---|---|---|---|---|
| Hardness (HRC) | ≤20 | 48–52 | 58–62 | 45–50 |
| Tensile Strength (MPa) | 520–720 | 1,200–1,500 | 2,000–2,200 | 1,400–1,600 |
| Yield Strength (MPa) | 205–450 | 1,000–1,300 | 1,800–2,000 | 1,200–1,400 |
| Elongation (%) | 20–30 | 8–12 | 3–5 | 10–15 |
| Impact Toughness (J/cm²) | 40–60 | 20–30 | 5–10 | 30–40 |
| Density (g/cm³) | 7.75 | 7.75 | 7.75 | 7.75 |
Key Advantages of Stainless Steel
- High Strength & Hardness:
- 440C achieves 2,200 MPa tensile strength, ideal for cutting tools.
- UGINOX MA4 offers 1,600 MPa strength with improved toughness.
- Heat Treatability:
- Quenching from 1,020–1,060°C in oil/air, followed by tempering (150–300°C).
- Age-hardening (UGINOX MA4) at 250°C for 2 hours enhances yield strength.
- Corrosion Resistance:
- Passive Cr₂O₃ layer provides moderate resistance to mild acids/chlorides.
- 440C’s high Cr (16–18%) improves pitting resistance in aggressive environments.
- Wear Resistance:
- 420/440C grades excel in bearings, valves, and surgical instruments.
Applications of Stainless Steel
| Industry | Components | Key Requirements |
|---|---|---|
| Cutting Tools | Drill bits, knives, razor blades | Ultra-high hardness (HRC 58–62), edge retention |
| Aerospace | Landing gear bearings, turbine blades | High fatigue strength, corrosion resistance |
| Medical | Surgical scalpels, orthopedic implants | Biocompatibility, sterilization resistance |
| Oil & Gas | Valve seats, pump shafts | Wear resistance, H₂S/CO₂ corrosion resistance |
| Automotive | Exhaust valves, fuel injector components | Heat resistance (up to 400°C), fatigue life |
Manufacturing Costs and Processing Considerations
- Raw Material Cost:
- 410: 1,500/ton.
- 420: 2,200/ton.
- 440C: 4,500/ton (due to high Cr, Mo content).
- UGINOX MA4: 5,000/ton (Ni addition).
- Processing Cost:
- Heat Treatment: 600/ton (quenching + tempering).
- Grinding/Polishing: +500/ton (for precision components).
- Total Cost:
- 410: 2,100/ton.
- 420: 2,800/ton.
- 440C: 5,100/ton.
- UGINOX MA4: 5,600/ton.
In Conclusion
HuaDa Metals has the good quality products and contact us. Martensitic stainless steels are indispensable in industries demanding high strength, hardness, and wear resistance with moderate corrosion resistance.
- 410 Grade: Cost-effective for general-purpose applications.
- 420 Grade: Balances hardness and toughness for mechanical components.
- 440C Grade: The benchmark for ultra-hard applications (cutting tools, bearings).
- UGINOX MA4: Offers superior toughness via age-hardening for critical aerospace/nuclear uses.