SUS420J2 stainless steel vs. SUS304: Key differences

If you are looking for stainless steel materials that meet high-strength, wear-resistant, or corrosion-resistant requirements, understanding the differences between SUS420J2 and SUS304 stainless steel is crucial. GNEE offers both grades in sheets, plates, and bars, with reliable quality, competitive pricing, and fast delivery for industrial projects.

What is the differences between SUS420J2 stainless steel and SUS304?

SUS420J2 is a martensitic stainless steel with a high carbon content (0.15%–0.4%) and a chromium content of 12%–14%. After heat treatment, it exhibits excellent hardness and wear resistance. In contrast, SUS304 is an austenitic stainless steel with a chromium content of 18%–20% and a nickel content of 8%–10.5%, possessing excellent corrosion resistance and ductility, but lower hardness.

 

 

SUS420J2 stainless steel vs. SUS304:Chemical composition

Property	SUS420J2	SUS304
Type	Martensitic	Austenitic
C (Carbon)	0.15 – 0.40%	≤0.08%
Cr (Chromium)	12 – 14%	18 – 20%
Ni (Nickel)	0 – 0.5%	8 – 10.5%
Mn (Manganese)	≤1%	≤2%
Si (Silicon)	≤1%	≤1%
P (Phosphorus)	≤0.04%	≤0.045%
S (Sulfur)	≤0.03%	≤0.03%

 

SUS420J2 stainless steel vs. SUS304:Mechanical properties

Property	SUS420J2	SUS304
Type	Martensitic	Austenitic
Tensile Strength	500 – 700 MPa (after heat treatment)	520 – 720 MPa
Yield Strength	205 – 450 MPa	205 – 310 MPa
Elongation	12 – 20%	≥40%
Hardness	Up to 500 HV (after heat treatment)	150 – 200 HV
Corrosion Resistance	Moderate	Excellent

 

Is SUS420J2 stainless steel magnetic?

SUS420J2 stainless steel is magnetic because it is a martensitic stainless steel, characterized by high carbon content and a crystal structure (ferrite) that makes it strongly attracted to magnets, even after heat treatment for hardening.

 

SUS420J2  vs SUS304 Stainless Steel: Corrosion Resistance

SUS420J2 stainless steel has moderate corrosion resistance due to its lower chromium content (12–14%) and high carbon content, making it suitable for dry or mildly corrosive environments, whereas SUS304 stainless steel, with 18–20% chromium and 8–10.5% nickel, provides excellent corrosion resistance in aggressive chemical, marine, and high-humidity applications.

 

SUS420J2 Stainless Steel vs SUS304 Stainless Steel: Hardness

After heat treatment, SUS420J2 stainless steel can achieve a hardness of up to 500 HV, offering superior wear resistance for cutlery, surgical instruments, and mechanical components, while SUS304 stainless steel has a lower hardness of 150–200 HV, prioritizing ductility and corrosion resistance over wear strength.

 

SUS420J2 Stainless Steel vs SUS304 : Weldability

SUS420J2 stainless steel is weldable but requires careful preheating and post-weld heat treatment to avoid cracking due to its martensitic structure, whereas SUS304 stainless steel, being fully austenitic, exhibits excellent weldability with minimal risk of intergranular corrosion, making it ideal for piping, tanks, and chemical processing equipment.

 

SUS420J2 vs SUS304 Stainless Steel: Price (2025 Reference)

Grade	Price per kg (USD)	Notes
SUS420J2	$4.50 – $6.50	Depends on thickness, size, and heat treatment
SUS304	$5.50 – $8.50	Depends on size, surface finish, and market fluctuations

 

GNEE supplies SUS420J2 and SUS304 stainless steel in forms including sheets, plates, bars, and pipes, with SUS420J2 offering high hardness up to 500 HV for wear-resistant applications and SUS304 providing excellent corrosion resistance for chemical and marine environments; all products meet ASTM, JIS, GB, and ISO 9001 standards and are carefully packaged with protective film, wooden crates, and palletized shipments to ensure safe international delivery.Email: info@gneestainless.com

SUS420J2 and SUS304 Stainless Steel Product Specifications

Grade	Form	Thickness	Width / Diameter	Length	Surface Finish
SUS420J2	Sheet / Plate / Bar	0.5 – 50 mm	100 – 2000 mm	1000 – 6000 mm	2B / Polished / Ground
SUS304	Sheet / Plate / Bar / Pipe	0.3 – 80 mm	10 – 2500 mm	1000 – 6000 mm	2B / BA / No.4 / Polished