Martensitic Stainless Steel is a heat-treatable class of stainless steels primarily alloyed with 12–18% chromium and controlled carbon content (0.10–1.20%). When quenched from high temperature, the steel transforms into a martensitic microstructure, delivering exceptional hardness, strength, and wear resistance.
Unlike austenitic grades, martensitic stainless steels are magnetic and can be hardened and tempered over a wide range of mechanical properties. Their corrosion resistance is moderate but sufficient for many mechanical, engineering, and industrial environments where strength is the dominant requirement.
Typical Chemical Composition
| Element | Typical Range (%) | Role |
|---|---|---|
| Chromium (Cr) | 12.0 – 18.0 | Corrosion resistance & hardenability |
| Carbon (C) | 0.10 – 1.20 | Hardness & strength |
| Nickel (Ni) | 0 – 2.0 | Improves toughness (select grades) |
| Manganese (Mn) | ≤ 1.0 | Deoxidation |
| Silicon (Si) | ≤ 1.0 | Oxidation resistance |
| Molybdenum (Mo) | ≤ 1.0 | Pitting resistance |
| Iron (Fe) | Balance | Base metal |
Microstructure & Metallurgical Behavior
Martensitic Structure
• Formed by rapid quenching from austenitizing temperature
• Hard, needle-like crystal structure
• Hardness increases with carbon content
• Tempering required to balance hardness and toughness
Heat-Treatability
• Can be quenched, tempered, or annealed
• Properties precisely tailored for application needs
Typical Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 750 – 1,750 MPa |
| Yield Strength | 450 – 1,500 MPa |
| Hardness | 30 – 58 HRC (heat treated) |
| Elongation | 8 – 20% |
| Density | 7.7 – 7.8 g/cm³ |
| Modulus of Elasticity | ~200 GPa |
| Impact Toughness | Moderate (improves after tempering) |
Key Characteristics
✔ Very high strength and hardness
✔ Heat treatable for tailored performance
✔ Moderate corrosion resistance
✔ Magnetic in all conditions
✔ Excellent wear and fatigue resistance
Refining & Processing Properties
• Produced via EAF with AOD or VOD refining
• Austenitized at 950–1,050 °C
• Quenched in oil, air, or gas
• Tempered at 150–600 °C depending on application
• Machinable in annealed condition
Available Forms
✔ Sheets & plates
✔ Coils
✔ Bars (round, square, flat, hex)
✔ Rods & forgings
✔ Pipes & tubes
✔ Wire & precision strips
Applications
Industrial: Pump shafts, valves, gears, bearings, springs
Automotive: Engine parts, transmission components, turbo shafts
Cutlery & Tools: Knives, blades, surgical instruments
Oil & Gas: Downhole tools, drilling equipment
Defense & Aerospace: High-strength wear-resistant components
Advantages
✔ Extremely high mechanical strength
✔ Adjustable hardness through heat treatment
✔ Good wear resistance
✔ Magnetic properties
✔ Precision engineering capability
Limitations
⚠ Lower corrosion resistance than austenitic stainless steel
⚠ Requires controlled heat treatment
⚠ Limited weldability in high-carbon grades
⚠ Reduced toughness in fully hardened condition
Why Choose Martensitic Stainless Steel
Martensitic stainless steel is selected when mechanical strength, hardness, and wear resistance are critical and corrosion exposure is moderate. Its heat-treatability and versatility make it indispensable for automotive, industrial, oil & gas, aerospace, and tool-making applications.