Stainless Steel 420
Stainless Steel 420 is a grade of high-carbon stainless steel which is very hard, corrosion resistant and able to take a sharp cut. It is typically used in tools, cutlery and surgical instruments making it tough and wear resistant over a considerable period.
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Martensitic Stainless Steel
The full designation ‘Stainless Steel 420’ makes it clear that there are certain composition and properties. The alloy generally contains 12-14% of chromium, 0.15-0.50% of carbon and some other elements like manganese, silicon, sulfur in minor amounts.
They are appropriate for processes such as annealing or hardening, tempering or machining. They can be welded if done carefully and can be adapted to processes which require great hardness and medium resistance to corrosion.


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Stainless Steel 420 Properties
Mechanical Properties
- Tensile Strength: 655 - 1620 MPa (varies with tempering temperature)
- Yield Strength: 345 - 1420 MPa
- Elongation: 10 - 25%
- Hardness: Up to 50 HRC
Physical Properties
- Density: 7800 kg/m³
- Elastic Modulus: 200 GPa
- Thermal Conductivity: 24.9 W/m.K
- Specific Heat: 460 J/kg.K
- Electrical Resistivity: 550 nΩ.m
Thermal Properties
Coefficient of Thermal Expansion: 10.3 - 11.7 μm/m/°C (varies with temperature)
Electrical Properties
Electrical Resistivity: 550 nΩ.m
Post Treatments
- Annealing: Heat to 840-900°C, slow furnace cooling, then air-cooling.
- Hardening: Heat to 980-1035°C, followed by air or oil quenching.
- Tempering: Performed at 150-370°C for high hardness.
Common Applications
- Cutlery (e.g., carving knives, table knives)
- Surgical instruments
- Shear blades
- Needle valves
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Frequently Asked Questions (FAQs)
Q: What is 420 stainless steel?
A: 420 stainless steel is a higher carbon martensitic stainless steel which demonstrates good corrosion resistant properties and high hardness. It usually contains approximately 12% of chromium and is suitable for several applications requiring a strong and hard material.
Q: What are the properties of 420 stainless steel?
A: 420 stainless steel is highly known for its properties such as high strength especially when subjected to heavy hardness when heat treated. The hardened condition can achieve hardness with a rating of about 55 HRC which makes it suitable for applications such as surgical instruments and cutlery.
Q: Does heat treatment change the properties of 420 stainless steel?
A: The impact of heat treatment on 420 stainless steel is large in terms of its hardness and strength. The adjustment involves hardening it through quenching and tempering, which increases both wear resistance and mechanical properties of the material.
Q: In which fields is 420 stainless steel applicable?
A: 420 stainless steel has many applications where good corrosion resistance and high hardness are the requirements. Examples of such applications are knives, surgical instruments and other types cutlery, valve parts, and shear blades.
Q: Is 420 stainless steel subject to significant corrosion?
A: 420 stainless steel is better resistant to corrosion as compared with that of carbon steel due to the presence of chromium. It should be understood however that, austenitic grades of stainless steels rank higher in corrosion resistance than the 420 grade.
Q: What are the components included in 420 stainless steel?
A: 420 stainless steel consists – of 12 to 14% chromium, 0.15% carbon, and other alloying elements, including manganese and silicon. This particular composition enhances its mechanical strength and improves its corrosion resistance ability.
Q: Is it possible to carry out the welding of 420 stainless steel?
A: 420 stainless steel can be welded but measures should be taken even in performing the welding since there will be a drop in some mechanical properties. Preheating and post-weld heat extend will assist in alleviating some of the problems changing color, especially when welding.
Q: In what scope does 420 stainless steel lie in when compared to other grades with regards to its physical properties?
A: The physical properties of 420 stainless steel, such as density, thermal conductivity, and magnetic properties, behave like that of similar other martensitic stainless steel grades like 410. In spite of this, in its heat treatment process, the martensic number takes a higher order owing to its higher carbon content.
Q: Why are UNS S42000 specifications key stipulations?
A: The UNS S42000 specification covers the 420 stainless steel specification in the system of classification. This specification makes certain that the material has defined requirements for its composition and mechanical properties, thereby facilitating the proper selection of steel by the manufacturers and engineers for their purposes.