SUS420J2 Stainless Steel: High-Carbon Martensitic Grade for Wear-Resistant Components

SUS420J2 is a high-carbon martensitic stainless steel (C=0.26%-0.35%, Cr=12.0%-14.0%) with higher hardenability than SUS420J1. After heat treatment, it can reach a hardness of 52-57HRC, with excellent wear resistance and edge retention, suitable for components requiring high wear resistance.

Core Parameters

Chemical Composition (wt%): C=0.26-0.35, Si≤1.00, Mn≤1.00, P≤0.040, S≤0.030, Cr=12.00-14.00, Fe=Balance

Mechanical Properties (Quenched & Tempered): Tensile Strength ≥820MPa, Yield Strength ≥620MPa, Elongation ≥12%, Hardness 52-57HRC

Service Temperature: -20℃ to 300℃ (continuous service)

Equivalent Grades: EN 1.4028, UNS S42020, GB 30Cr13

Performance Advantages: Higher carbon content ensures high hardness and wear resistance; good grindability, can be polished to a mirror finish; moderate corrosion resistance in dry environments; suitable for making components with high wear requirements.

Typical Applications: High-hardness kitchen knives, hunting knives, utility knives, bearing balls, valve seats, mold cores for wear-resistant requirements, measuring tools, textile machine needles.

Practical Q&A

Q1: What heat treatment process is required for SUS420J2 to achieve high hardness? A1: Quenching at 1000-1070℃, oil cooling + tempering at 150-200℃, air cooling. This process maximizes hardness (52-57HRC) and wear resistance. Avoid tempering at 300-450℃ to prevent temper brittleness.

Q2: Is SUS420J2 suitable for making cutting tools? A2: Yes. Its high hardness (52-57HRC) and good edge retention make it suitable for making cutting tools such as knives and scissors. However, it is not suitable for tools used in corrosive environments due to its limited corrosion resistance.

Q3: What is the wear resistance of SUS420J2 compared to SUS420J1? A3: The wear resistance of SUS420J2 is 1.5-2 times that of SUS420J1. In the abrasive wear test, the wear loss of SUS420J2 is only 0.02g after 1000 cycles, while that of SUS420J1 is 0.035g.

Q4: Can SUS420J2 be cold worked? A4: Cold working is difficult in the hardened state due to high hardness. It should be cold worked in the annealed state (hardness ≤229HB), and the single deformation should not exceed 20% to avoid cracking. Intermediate annealing is required after cold working.

Q5: How to improve the corrosion resistance of SUS420J2 cutting tools? A5: After heat treatment, perform passivation treatment with 20% nitric acid solution to form a dense oxide film; apply anti-rust oil to the surface when not in use; avoid contact with acidic foods or liquids during use.