What is 1.4021 Stainless Steel?

1.4021 stainless steel, commonly known as 420 or UNS S42000, is a martensitic stainless steel with moderate corrosion resistance and the ability to be hardened to achieve high strength and wear resistance. It is widely used for cutlery, surgical instruments, and various mechanical components where hardness, edge retention, and moderate corrosion resistance are required.

 

This hardenable martensitic grade is standardized under several international systems.

Standard	Equivalent Grade
EN (Europe)	1.4021
ASTM/AISI (USA)	420, UNS S42000
JIS (Japan)	SUS420J1
KS (Korea)	STS420

Its composition is centered around chromium for corrosion resistance and carbon for hardenability.

Element	C	Si	Mn	P	S	Cr
Content (%)	0.16 - 0.25	≤ 1.0	≤ 1.5	≤ 0.04	≤ 0.03	12.0 - 14.0

Mechanical properties vary significantly based on heat treatment (annealed vs. hardened & tempered).

Condition	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HRC)
Annealed	~ 345 MPa	~ 655 MPa	~ 20%	~ 20 HRC
Hardened & Tempered	≥ 550 MPa	≥ 740 MPa	≥ 12%	50 - 55 HRC

 

Key Characteristics and Applications of 1.4021 / 420

High Hardness and Wear Resistance: Can be heat treated to achieve high surface hardness (up to ~55 HRC), providing excellent wear resistance and edge retention.

Moderate Corrosion Resistance: Provides reasonable resistance to water, mild chemicals, and atmospheric conditions, but is not suitable for severe corrosive environments.

Magnetic and Machinable: Strongly magnetic in all conditions. In the annealed state, it offers fair machinability.

 

Primary Applications:

Cutlery and Blades: Knives, scissors, razors, and surgical scalpels.

Surgical and Dental Instruments: Forceps, clamps, and dental tools.

Industrial Components: Pump shafts, valve seats, bearings, and molds.

General Engineering: Wear plates, guides, and other components requiring hardness.

 

What is the typical heat treatment process for 420 (1.4021) stainless steel?
The process involves hardening: heating to 980-1050°C, holding to achieve full austenitization, followed by oil or air quenching to form a hard martensitic structure. This is followed by tempering: reheating to a temperature between 150-400°C (depending on desired hardness/toughness balance) to relieve internal stresses and achieve the final mechanical properties. Lower tempering temperatures yield higher hardness but lower toughness; higher temperatures increase toughness with some reduction in hardness. Annealing is performed at 830-900°C with slow cooling to soften the material for machining.

 

How does 420 stainless steel compare to 440C in terms of performance?
Both are martensitic cutlery steels, but 440C contains higher carbon (0.95-1.20%) and chromium (16-18%), allowing it to achieve much higher hardness (up to 62 HRC) and slightly better corrosion resistance. 420 is considered a "softer" stainless with better toughness and easier machinability in the annealed state. 440C is used for high-end knives and bearings where maximum wear resistance is needed, while 420 is common for general-purpose cutlery and surgical tools where a balance of hardness, toughness, and corrosion resistance is required.

 

Looking for a Reliable Supplier of 1.4021 / 420 Stainless Steel?
GNEE Steel supplies versatile 420 (1.4021) martensitic stainless steel in bar, wire, sheet, and strip forms, available in annealed or heat-treated conditions to meet specific hardness and strength requirements. We provide material certification and processing support. If you have any requirements, please feel free to contact us.