420 Stainless Steel: Uses, Composition, Properties

Among the many stainless steel grades available, 420 stainless steel stands out as a versatile martensitic alloy known for its high hardness, wear resistance, and moderate corrosion resistance.

Thanks to its ability to be heat-treated for enhanced strength, AISI 420 stainless steel is widely used in industries that require durable components such as cutlery, surgical tools, industrial parts, and mechanical equipment.

This guide explains the properties, chemical composition, heat treatment process, and common applications of 420 stainless steel, helping engineers, manufacturers, and buyers better understand when this material is the right choice.

Related Products:

420 Stainless Steel Coil    Stainless Steel Strip    420 Stainless Steel Sheet

What Is 420 Stainless Steel?

420 stainless steel is a martensitic stainless steel grade containing high carbon content and approximately 12–14% chromium, which provides a balance between hardness, strength, and corrosion resistance.

Key characteristics include:

  • High hardness after heat treatment

  • Excellent wear resistance

  • Moderate corrosion resistance

  • Good polishability

  • Magnetic properties

Due to these characteristics, AISI 420 stainless steel is commonly selected for applications that require sharp edges, mechanical durability, and abrasion resistance.

However, in highly corrosive environments such as marine or chemical exposure, grades like 304 or 316 stainless steel may provide better corrosion protection.

Chemical Composition of 420 Stainless Steel

Typical chemical composition of 420 stainless steel:

Element Content
Carbon 0.15 – 0.40%
Chromium 12 – 14%
Manganese ≤1%
Silicon ≤1%
Nickel ≤0.5%
Molybdenum ≤0.5%
Phosphorus ≤0.04%
Sulfur ≤0.03%
Copper ≤0.5%
Aluminum ≤0.15%
Iron Balance

The relatively high carbon content is responsible for the steel’s ability to achieve high hardness after heat treatment.

Mechanical Properties of 420 Stainless Steel

Typical mechanical properties of annealed 420 stainless steel include:

Property Value
Density 7.74 g/cm³
Elastic Modulus 200 GPa
Tensile Strength ~655 MPa
Yield Strength 40,000 psi (annealed)
Elongation 25%
Brinell Hardness ≤241 HB

After heat treatment, hardness can increase significantly, making 420 steel suitable for cutting tools and precision components.

Is 420 Stainless Steel Magnetic?

Yes, 420 stainless steel is magnetic.

This is because it belongs to the martensitic stainless steel family, which forms a ferromagnetic crystal structure after heat treatment. Unlike austenitic stainless steels such as 304 or 316, martensitic steels retain strong magnetic properties.

Thermal Properties of 420 Stainless Steel

Important thermal properties include:

Property Value
Melting Point ~1495°C
Thermal Conductivity (100°C) 25 W/m·K
Thermal Conductivity (500°C) 28.7 W/m·K
Specific Heat 0.46 kJ/kg·K
Thermal Expansion 10–12 µm/m·K

Because of its moderate heat resistance, 420 stainless steel is typically not recommended for continuous service above 500–550°C.

Heat Treatment of 420 Stainless Steel

One of the key advantages of AISI 420 stainless steel is its ability to be hardened through heat treatment.

Annealing

To soften the material for machining:

  • Heat to 840–900°C

  • Hold temperature for adequate time

  • Furnace cool slowly to about 600°C

  • Air cool to room temperature

This process reduces internal stresses and improves machinability.

Hardening

To increase hardness and strength:

  • Heat to 980–1035°C

  • Quench rapidly in oil or air

  • Temper at a controlled temperature depending on desired hardness

Tempering allows carbide formation and balances hardness with toughness.

Common Forms of 420 Stainless Steel

420 stainless steel is available in several product forms for industrial manufacturing:

Stainless Steel Sheet

Typically 0.5–3 mm thick, used for components requiring corrosion and wear resistance.

Stainless Steel Plate

Thicker sections used for structural components or machining parts.

Stainless Steel Bar

Round or rectangular bars used for shafts, fasteners, and mechanical components.

Cold Drawn Stainless Steel

Improves dimensional accuracy and surface finish.

Hot Rolled Stainless Steel

Offers improved ductility and is easier to form.

Applications of 420 Stainless Steel

Because of its high hardness and wear resistance, 420 stainless steel is widely used in applications requiring durable cutting edges and mechanical strength.

Common applications include:

  • Cutlery and knife blades

  • Surgical instruments

  • Needle valves

  • Pump shafts

  • Bearings

  • Valve components

  • Fasteners

  • Screens and filters

  • Steam and gas equipment

  • Turbine parts

  • Hand tools

Its ability to maintain sharp edges makes it especially popular for industrial cutting tools and medical instruments.

Equivalent Grades of 420 Stainless Steel

Standard Equivalent Grade
UNS S42000
EN 1.4021
DIN X20Cr13
JIS SUS420J1
Swedish SS 2303
British BS 420S37

These equivalents help engineers identify compatible materials across international standards.

Advantages and Limitations of 420 Stainless Steel

Advantages

  • High hardness after heat treatment

  • Excellent wear and abrasion resistance

  • Good corrosion resistance in mild environments

  • Cost-effective compared with higher alloy stainless steels

Limitations

  • Lower corrosion resistance than 304 or 316 stainless steel

  • Welding requires careful control to avoid cracking

  • Limited high-temperature resistance above 500°C

Conclusion

420 stainless steel is a versatile martensitic alloy valued for its high hardness, wear resistance, and heat-treatable strength. These properties make it a popular material for cutting tools, industrial components, and medical instruments.

While it may not provide the same corrosion resistance as 304 or 316 stainless steels, its excellent mechanical performance and cost efficiency make AISI 420 stainless steel a reliable option for many engineering and manufacturing applications.