Today we are going to discuss 420 stainless steel. Japanese standards divide 420 stainless steel into SUS420J1 and SUS420J2. The difference between these two stainless steel grades seems to be just one number. So what is the difference between these two materials? Please see below!
SUS420J1 stainless steel has certain wear resistance and corrosion resistance, high hardness, and is suitable for working environments with ordinary requirements for stainless steel.
SUS420J2 martensitic stainless steel is mainly composed of chromium (CR) and a small amount of carbon (C), usually containing about 0.26% to 0.40% carbon. Due to the high chromium content, it has certain corrosion resistance and is suitable for general daily use environments.
SUS 420J1 vs SUS420J2 stainless steel Chemical composition
| Chemical composition | SUS420J1 | SUS420J2 |
|---|---|---|
| Carbon (C) | 0.16-0.25 | 0.26-0.35 |
| Silicon (Si) | ≤1.00 | ≤1.00 |
| Manganese (Mn) | ≤1.00 | ≤1.00 |
| Phosphorus (P) | ≤0.040 | ≤0.040 |
| Sulfur (S) | ≤0.030 | ≤0.030 |
| Nickel (Ni) | ~ | ≤0.60 |
| Chromium (Cr) | 12.00-14.00 | 12.00-14.00 |
SUS 420J1 vs SUS420J2 stainless steel Physical properties
| Performance Category | parameter | SUS420J1 | SUS420J2 |
|---|---|---|---|
| Physical properties | (Density) | 7.75 g/cm³ | 7.75-7.76 g/cm³ |
| (Elastic Modulus) | 200-210 GPa | 219 GPa (approx.) | |
| (Thermal Conductivity) | 25-30 W/(m·K) | 25.1 W/(m·K) at 100℃ | |
| (Thermal Expansion Coefficient) | ~11-12 × 10⁻⁶/K | 10.5 × 10⁻⁶/K (0~100℃) | |
| Mechanical properties | (Yield Strength) | ≥225 N/mm² | |
| (Tensile Strength) | ≥440 N/mm² | ||
| (Reduction of Area) | ≥50% | ||
| (Hardness) | HRC 50-55 | ||
| (Elongation) | ≥12% / ≥50% |
SUS 420J1 vs SUS420J2 stainless steel Equivalent Standards
| standard | SUS420J1 | SUS420J |
|---|---|---|
| GB | 20Cr13 | 30Cr13 |
| JIS | SUS420J1 | SUS420J2 |
| ASTM |
S42000 420 |
S42000 420 |
| EN |
X20Cr13 1.4021 |
X30Cr13 1.4028 |
Characteristics and Uses
SUS420J1 stainless steel: high hardness and good corrosion resistance in quenched state. Used for turbine blades.
SUS420J2 stainless steel: higher hardness than SUS420J1 (20Cr13) stainless steel after quenching, used for cutting tools, nozzles, valve seats, valves, etc.
Heat treatment system
SUS420J1 stainless steel: annealing treatment is about 750℃ fast cooling or 800℃~900℃ slow cooling
SUS420J2 stainless steel: annealing treatment is about 750℃ fast cooling or 800℃~900℃ slow cooling; quenching is 980℃~1040℃ fast cooling; tempering is 150℃~400℃ air cooling.
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