SUS440 – High-Carbon Martensitic Alloy For Extreme Wear & Edge Retention

Overview

SUS440 is a high-carbon martensitic stainless steel family under JIS G 4303, renowned for its exceptional hardness, wear resistance, and moderate corrosion resistance. With 16.00-18.00% chromium and 0.95-1.20% carbon, it achieves ultra-high hardness (up to 60 HRC) after heat treatment, making it one of the most wear-resistant JIS stainless steel grades. It contains a small addition of molybdenum to enhance corrosion resistance and hardenability. It is magnetic, has good machinability when annealed, and is specifically designed for applications requiring extreme wear resistance and edge retention, though careful heat treatment is needed to avoid brittleness.

Chemical Composition (wt%)

C: 0.95-1.20, Cr: 16.00-18.00, Mo ≤ 0.75, Mn ≤ 1.00, Si ≤ 1.00, P ≤ 0.040, S ≤ 0.030, Ni ≤ 0.75

Typical Mechanical Properties (Quenched & Tempered Condition)

Tensile Strength (Rm): ≥ 1900 MPa; Yield Strength (Rp0.2): ≥ 1700 MPa; Elongation (A): ≥ 2%; Hardness (HRC): 58-60

Core Advantages

Ultra-high hardness and wear resistance after heat treatment; excellent edge retention for cutting tools; moderate corrosion resistance in mild environments; magnetic; good machinability in the annealed state; high-temperature dimensional stability; suitable for extreme wear-intensive applications.

Applications

High-performance knives, surgical instruments, precision bearings, valve components, pump shafts, watch parts, and tactical tools requiring extreme wear resistance and edge retention.

Equivalent Grades

EN 1.4125, UNS S44004, GB 11Cr17, AISI 440C

Stainless Steel Suppliers

If you have project requirements for stainless steel, we welcome your order. GNEE has a large inventory of popular products for you to choose from. It can be processed into various practical product forms, including plates, coils, tubes, bars, wires, etc. For detailed chemical composition information and free samples, please contact our factory immediately. We offer competitive prices and excellent service.Email: info@gneestainless.com

 

Testing and Documentation: Factory test certificate, EN 10204 3.1, chemical report, mechanical report, destructive testing report, non-destructive testing report, PMI test report, visual inspection report, third-party inspection report, NABL certified laboratory report.
Packaging: Wooden crate packaging, bubble wrap packaging, steel strapping, or packaging according to customer requirements.