SUS420J2 VS. SUS420J1 : Carbon Content & Hardness

What is SUS420J2 material?

SUS420J2 is a steel with a chromium content of 12-14%. Through heat treatment, it possesses high hardness and wear resistance, and moderate corrosion resistance in mild environments. SUS420J2 is commonly used in knives, cutlery, surgical instruments, and machine parts, making it an economical choice.

 

What is SUS420J1 stainless steel?

SUS420J1 is a martensitic stainless steel conforming to Japanese Industrial Standard (JIS) (containing 12-14% chromium and approximately 0.16-0.25% carbon). It has high hardenability, moderate corrosion resistance, and excellent wear resistance, and is commonly used in the manufacture of tableware, knives, and surgical instruments. Compared to SUS420J2, it has better toughness and machinability, and achieves higher hardness (typically greater than or equal to 50 HRC) through quenching and tempering processes.

 

420J2 vs 420J1 Stainless Steel: Which Is Best for Knife Making?

420J2 is generally considered the better choice for knife making between the two, offering higher carbon content, superior hardness, and better edge retention, making it ideal for kitchen knives, diving knives, and budget folding blades. While 420J1 is more corrosion-resistant and easier to sharpen, its lower hardness (approx. 48–50 HRC) makes it better suited for lower-cost items or utility knives that do not require high edge retention.

 

SUS420J2 VS. SUS420J1 : Chemical Composition (Weight %)

SUS420J2 is essentially a higher-carbon version of SUS420J1.

Element	SUS420J1 (%)	SUS420J2 (%)
Carbon (C)	0.16 – 0.25	0.26 – 0.40
Chromium (Cr)	12.00 – 14.00	12.00 – 14.00
Manganese (Mn)	≤ 1.00	≤ 1.00
Silicon (Si)	≤ 1.00	≤ 1.00
Phosphorus (P)	≤ 0.040	≤ 0.040
Sulphur (S)	≤ 0.030	≤ 0.030
Nickel (Ni)	≤ 0.60 (Optional)	≤ 0.60 (Optional)

 

SUS420J2 VS. SUS420J1 :Mechanical Properties (After Heat Treatment)

The performance gap is most noticeable after quenching and tempering. SUS420J2 can reach a significantly higher hardness.

Property	SUS420J1	SUS420J2
Hardness (Rockwell C)	42 – 48 HRC	50 – 54 HRC
Tensile Strength	≥ 590 MPa	≥ 735 MPa
Yield Strength (0.2%)	≥ 440 MPa	≥ 540 MPa
Elongation	≥ 15%	≥ 12%
Reduction of Area	≥ 45%	≥ 40%
Structure	Martensitic	Martensitic

 

What is the equivalent standard for SUS420J2 stainless steel?

SUS420J2 is a Japanese (JIS) martensitic stainless steel, whose main international corresponding standards include AISI 420 (USA), EN 1.4028 / X30Cr13 (Europe) and 3Cr13 (China).

 

SUS420J2 vs. SUS420J1 Stainless Steel: Heat Treatment

Both SUS420J2 and SUS420J1 are martensitic stainless steels, differing mainly in their carbon content, which affects their maximum hardness after heat treatment. SUS420J2 (0.26-0.40% carbon content) has higher hardness, strength, and corrosion resistance than SUS420J1 (0.16-0.25% carbon content). Both require quenching (980-1040℃) and tempering (150-400℃) to achieve optimal performance.

 

SUS420J2 vs. SUS420J1 Stainless Steel: Hardness

Due to its higher carbon content (0.26-0.40% vs 0.16-0.25%), SUS420J2 is generally harder than SUS420J1. Although both are martensitic stainless steels, the higher carbon content of J2 allows it to achieve a hardness of approximately 54-56 HRC after heat treatment, while J1 is softer, typically around 48-50 HRC. Therefore, J2 is better suited for high-strength/high-hardness applications, such as cutting tools, while J1 is better suited for corrosion-resistant applications.

 

SUS420J2 vs. SUS420J1 Stainless Steel: Applications

SUS420J2: High-quality kitchen knives, scissors, fasteners, and surgical tools.
SUS420J1: Turbine blades, industrial machinery parts, and general tools.

 

Delivery Conditions:
* Annealed (+A): Low factory hardness (≤ 225 HBW), facilitating machining operations such as cutting, drilling, and milling.
* Quenched & Tempered (+QT): Pre-treated to a specified hardness range (e.g., HRC 45-52) according to customer requirements, reducing the risk of deformation during subsequent heat treatment.

 

Why source SUS420J2 from GNEE?

We can provide batches with a carbon content consistently at the upper limit (close to 0.40%), ensuring a stable hardness of HRC 52 or higher after quenching. Our thick plates have high flatness and uniform internal structure, making them less prone to warping after processing.

 

SUS420J2 Stainless Steel Bars (Round Bars / Rods)

Product Form	Size Range	Surface Condition
Round Bar	Diameter: Φ 2 mm – Φ 600 mm	Black, Peeled, Bright, Centerless Ground
Hex Bar	Across Flats: S 4 mm – S 100 mm	Cold Drawn Bright
Square Bar	4 mm × 4 mm – 200 mm × 200 mm	Hot Rolled, Forged

 

SUS420J2 Stainless Steel Sheets & Plates

Product Form	Thickness Range	Width & Length	Surface Finish
Cold Rolled Sheet	0.3 mm – 6.0 mm	Width: 1000 / 1219 / 1500 mm	2B, BA, No.4, 8K Mirror
Hot Rolled Plate	3.0 mm – 150 mm	Max Width: 2500 mm	No.1, Pickled
Precision Strip (Coil/Strip)	0.05 mm – 2.0 mm	Slitting customization available	Bright, Hard / Soft Condition Customizable

Material Certification: EN 10204 3.1 Material Certificate (MTC) is provided with the shipment, including chemical composition (C, Cr, Mn, etc.) and mechanical properties.

Testing Methods: 100% PMI spectral analysis (ensuring the material is not 420J1 or 430); Ultrasonic testing (UT) ensures that thick plates and forgings are free of sand holes and cracks.

Export Packaging: Export-grade reinforced packaging (wooden pallets, wooden crates, rust-proof paper wrapping) ensures rust-free long-distance sea transport.