JIS G4304 / G4312 SUS 420J2 Stainless Steel Composition & High‑Hardness Martensitic Properties
SUS 420J2 is a high‑hardness martensitic stainless steel defined in JIS G4304 / G4312. With 12–14% chromium and about 0.30% carbon, it can be hardened to 48–52 HRC, making it a common material for cutting tools.
It is widely used for knives, scissors, surgical instruments, measuring tools, shafts, and wear‑resistant components. Its corrosion resistance is moderate and suitable for mildly corrosive environments. SUS 420J2 is supplied as sheets, strips, bars, and forgings. It is a preferred material for toolmaking, medical devices, and precision mechanical parts requiring high hardness.
It is widely used for knives, scissors, surgical instruments, measuring tools, shafts, and wear‑resistant components. Its corrosion resistance is moderate and suitable for mildly corrosive environments. SUS 420J2 is supplied as sheets, strips, bars, and forgings. It is a preferred material for toolmaking, medical devices, and precision mechanical parts requiring high hardness.