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420 Stainless Steel

420 Stainless Steel (UNS S42000) is a high-carbon, martensitic stainless steel well-regarded for its exceptional hardness and moderate corrosion resistance. Known as “surgical steel,” it has widespread applications in medical instruments, cutlery, and hand tools. With a minimum of 12% chromium, it provides satisfactory corrosion resistance and is notably hardenable through heat treatment, reaching a maximum Rockwell hardness of 50 HRC.

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Chemical Composition of 420 Stainless Steel

Element	Content (%)
Carbon (C)	0.15 max
Chromium (Cr)	12.0 – 14.0
Manganese (Mn)	≤ 1.00
Silicon (Si)	≤ 1.00
Phosphorus (P)	≤ 0.04
Sulfur (S)	≤ 0.03
Iron (Fe)	Balance

Technical Specifications of 420 Stainless Steel

Physical Properties

Property	Metric	Imperial
Density	7.74 g/cm³	0.280 lb/in³
Elastic Modulus	200 GPa	29 x 10⁶ psi
Thermal Conductivity (at 100°C)	24.9 W/m·K	15.1 BTU/hr·ft·°F
Coefficient of Thermal Expansion	10.3 µm/m°C	5.8 x 10⁻⁶ in/in°F
Specific Heat	460 J/kg·K	0.11 BTU/lb·°F
Electrical Resistivity	550 nΩ·m	23.68 µΩ·in
Melting Point	1454 – 1510°C	2650 – 2750°F

Mechanical Properties

Condition	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation (%)	Hardness (Rockwell B)
Annealed	655	345	25	241 max
Tempered (204°C)	1600	1360	12	444
Tempered (427°C)	1620	1420	10	461
Tempered (538°C)	1305	1095	15	375

Thermal Properties

Property	Metric	Imperial
Thermal Conductivity (at 100°C)	24.9 W/m·K	15.1 BTU/hr·ft·°F
Coefficient of Thermal Expansion	10.3 µm/m°C	5.8 x 10⁻⁶ in/in°F
Melting Point	1454 – 1510°C	2650 – 2750°F

Electrical Properties

Property	Metric	Imperial
Electrical Resistivity	550 nΩ·m	23.68 µΩ·in

Product Specifications by Solitaire Steel & Engineering LLP

Product Type	Standards	Sizes	Types	Applications
Sheets & Plates	ASTM A240	Thickness: 1.5mm – 50mm	Hot Rolled, Cold Rolled	Cutlery, medical tools, industrial blades
Pipes & Tubes	ASTM A268, A249	Diameter: 6mm – 1200mm	Seamless, Welded	Surgical equipment, valve components
Bars	ASTM A276	Diameter: up to 100mm	Round, Square, Hex	Tools, pump shafts, hand tools
Angles, Channels, Beams	ASTM A484	Custom sizes available	L-Angles, U-Channels, I-Beams	Structural support, general hardware
Fittings	ASTM A403	Size: 1/2″ – 72″	Buttweld, Socket Weld	Precision engineering, decorative hardware

Processing and Fabrication Properties of 420 Stainless Steel

Forming: Suitable for minor cold working, but extreme operations may lead to cracking.
Welding: Not typically welded due to high hardening; can be preheated to 150-320°C and post-heated to 610-760°C if welding is necessary.
Heat Treatment:
- Annealing: Heat to 840-900°C, followed by slow furnace cooling.
- Hardening: Heat to 980-1035°C, then oil quench for optimal hardness.
- Tempering: Temper at 150-370°C to improve hardness and mechanical properties; avoid tempering between 425-600°C.
Heat Resistance: Scaling resistance up to 650°C; avoid use above this to maintain mechanical properties.
Machinability: Easily machined in the annealed condition, challenging once hardened above 30 HRC.

Applications of 420 Stainless Steel

Due to its combination of hardness and corrosion resistance, 420 Stainless Steel is suitable for:

Medical Instruments: Surgical tools, dental instruments, and hypodermic needles.
Industrial Cutting Tools: Shear blades, knife blades, and scissors.
Hand Tools: Wrenches, screwdrivers, and general-purpose blades.
Pump and Valve Components: Used in high-wear environments requiring resistance to mild corrosion.