The Chinese standard blade steel — GB/T 1220 4Cr13, C 0.36–0.45%, Cr 12.0–14.0%, quenched and tempered to 48–53 HRC. Broadly equivalent to AISI 420HC, SUS420J2 and X46Cr13. Supplied annealed for blanking or hardened-and-tempered to your band.
4Cr13 sits at the sweet spot of the martensitic stainless family: enough carbon for a hard edge, enough chromium for useful corrosion resistance, and lean enough alloy content to stay cost-competitive at high volume.
More carbon means higher peak hardness (48–53 vs. 40–45 HRC) and better edge retention — the right call for blades and cutting edges. 2Cr13 is tougher and more ductile for valve stems and shafts.
Choose 4Cr13 when the part takes an edge or wears.Austenitic 301 and 304 resist corrosion better but cannot be quench-hardened. 4Cr13 is the only route when you need a 50 HRC edge in a stainless material — surgical blades are not made from 304.
Choose 4Cr13 when hardness is non-negotiable.7C27Mo2 adds molybdenum and higher carbon for premium edge retention in high-end knives. 4Cr13 delivers 90% of the performance at a lower material cost for high-volume blade and bearing production.
Choose 4Cr13 for cost-sensitive volume parts.Values below are the standard specification range for 4Cr13. Actual heat chemistry is reported on the Mill Test Certificate for every coil.
| Element | 4Cr13 (GB/T 1220) % | Notes |
|---|---|---|
| Carbon (C) | 0.36 – 0.45 | Primary hardening element; controls peak hardness |
| Chromium (Cr) | 12.0 – 14.0 | Provides corrosion resistance and forms hard carbides |
| Manganese (Mn) | ≤ 1.00 | Deoxidizer; mild hardenability contribution |
| Silicon (Si) | ≤ 1.00 | Deoxidizer |
| Phosphorus (P) | ≤ 0.035 | Residual; controlled for toughness and edge integrity |
| Sulfur (S) | ≤ 0.030 | Residual; controlled for shear-face quality |
| Nickel (Ni) | ≤ 0.60 | Residual; optional addition for toughness |
Reference: GB/T 1220 — Stainless steel bars. Strip product chemistry follows the same grade specification. Values typical per standard, actual confirmed on MTC. For SUS420J2 (JIS G4304), the carbon range is 0.26–0.40% with the same 12–14% Cr — broadly equivalent but not identical.
4Cr13 is supplied in two conditions. The annealed condition is for blanking and forming; the hardened-and-tempered condition is for finished wear and edge parts.
| Condition | Hardness (typ.) | Tensile (typ.) | Typical use |
|---|---|---|---|
| Annealed (soft) | ≤ 235 HB | ~600 – 750 MPa | Blanking, forming, stamping — part is quenched afterwards |
| Quenched & tempered (200–300°C) | 48 – 53 HRC | ~1,200 – 1,500 MPa | Surgical blades, knives, bearing races, valve seats |
| Quenched & tempered (400–500°C) | 40 – 45 HRC | ~900 – 1,100 MPa | Shafts, valve stems — toughness prioritized over peak hardness |
Values typical per GB/T 1220 and standard heat treat practice; actual confirmed on MTC. Hardness after quenching depends on section size, quench medium and tempering temperature. Thin strip (≤1 mm) achieves full hardness more readily than heavy sections.
4Cr13 is the Chinese designation. The same material family is known by different names in American, Japanese and European standards — chemistry ranges overlap but are not identical. Confirm against your governing standard before substitution.
| Standard | Grade | C (%) | Cr (%) | Notes |
|---|---|---|---|---|
| GB/T 1220 (China) | 4Cr13 | 0.36 – 0.45 | 12.0 – 14.0 | Base reference |
| ASTM / AISI (USA) | 420HC | ~0.40 – 0.50 | 12.0 – 14.0 | High-carbon 420 variant; knife and blade grade |
| JIS G4304 (Japan) | SUS420J2 | 0.26 – 0.40 | 12.0 – 14.0 | Cutlery and surgical instrument grade |
| EN 10088 (Europe) | X46Cr13 (1.4034) | 0.43 – 0.50 | 12.5 – 14.5 | European equivalent; slightly higher C and Cr |
| GOST (Russia) | 40Kh13 / 420 | 0.36 – 0.45 | 12.0 – 14.0 | Closest CIS equivalent |
Equivalents are approximate. Chemistry ranges differ between standards — for regulated or safety-critical parts, confirm the full chemistry against your governing specification and the MTC of the delivered heat.
The cycle below is the industry-standard route for 4Cr13 strip. Exact parameters should be confirmed for your section size and target hardness.
Heat to 1000–1050°C and hold for sufficient time (typically 5–15 minutes per mm of section) to fully dissolve carbides and form austenite. Too low → incomplete hardening; too high → grain growth and brittleness.
Oil quench is standard for 4Cr13 — faster than air, less severe than water. Thin strip (≤1 mm) may air-harden fully. Quench distortion is managed by fixturing or press-quenching for flat parts.
Temper at 200–300°C for 1–2 hours to reach 48–53 HRC with maximum edge retention. For tougher parts (shafts, valves), temper at 400–500°C to drop to 40–45 HRC. Avoid the 400–550°C temper embrittlement range if toughness is critical.
After heat treat and grinding, nitric or citric acid passivation restores the chromium oxide surface layer — required for medical and food-contact parts to meet corrosion and biocompatibility expectations.
0.10–0.40 mm strip, slit to 6–25 mm, blanked or etched in the annealed state, then quenched to 50–54 HRC and passivated. Chemistry aligns with ISO 7153-1 martensitic stainless types for surgical instruments.
Thin-gauge 4Cr13 takes a sharp, durable edge at high volume. Consistent carbon across the coil keeps the quench hardness within a tight band — critical for blade feel and edge life on automated production lines.
Packaging, textile and food-processing blades that see abrasion plus washdown. 4Cr13 resists corrosion from cleaning chemicals while maintaining a working edge — a step up from carbon tool steel in wet environments.
Thin-strip 4Cr13 formed into bearing races, through-hardened to 48–53 HRC. The chromium content gives corrosion resistance in humid or lightly corrosive environments where standard 52100 bearing steel would pit.
Valve seats, discs and trim parts in fluid-handling equipment. 4Cr13 provides wear resistance at the seating surface plus corrosion resistance to water, steam and mild chemicals — a common choice in the 420 stainless valve family.
Kitchen knives, scissors and hand tools where the consumer expects both sharpness and rust resistance. 4Cr13 / SUS420J2 is the workhorse grade for mid-range cutlery worldwide.
These grade families share material, processing or application territory with the topic on this page.
301 / 304 / 316 grades with excellent corrosion resistance and formability for springs, medical and food parts.
SK5 / SK7 / T8A / T10A grades with wear resistance and edge hardness for cutting tools.
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