SUS440B – Medium-Carbon 440-Series Martensitic Alloy For Enhanced Wear Performance

Overview

SUS440B is the medium-carbon variant of the JIS 440-series, offering higher wear resistance than SUS440A while maintaining good toughness. With 0.75-0.95% carbon and 16.00-18.00% chromium, it achieves a hardness of 56-58 HRC after heat treatment, making it suitable for applications requiring increased wear durability. It contains molybdenum to improve corrosion resistance and hardenability, and is magnetic with good machinability when annealed. Compared to SUS440A, it requires more careful heat treatment to avoid brittleness, but delivers superior wear performance for heavy-duty applications.

Chemical Composition (wt%)

C: 0.75-0.95, Cr: 16.00-18.00, Mo: 0.75-1.25, Mn ≤ 1.00, Si ≤ 1.00, P ≤ 0.040, S ≤ 0.030, Ni ≤ 0.75

Typical Mechanical Properties (Quenched & Tempered Condition)

Tensile Strength (Rm): ≥ 1930 MPa; Yield Strength (Rp0.2): ≥ 1860 MPa; Elongation (A): ≥ 3%; Hardness (HRC): 56-58

Core Advantages

Higher wear resistance than SUS440A; good toughness and corrosion resistance; heat-treatable to high hardness; magnetic; good machinability in the annealed state; excellent edge retention for heavy-duty cutting tools; suitable for wear-intensive applications.

Applications

Heavy-duty knives, bearings, gears, valve components, surgical instruments, industrial cutting tools, and precision parts requiring enhanced wear resistance and moderate corrosion protection.

Equivalent Grades

EN 1.4125, UNS S44003, GB 9Cr18Mo, AISI 440B

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.