Stainless Steel grades

The basic martensitic stainless steel — 12% chromium with moderate carbon. Hardenable by heat treatment to provide good strength with moderate corrosion resistance. Used for steam turbine blades, pump shafts, valve components, bolts, and mining equipment.

Medium-carbon martensitic stainless steel. Higher hardness than 410 but lower than 420C (1.4034). Good balance of strength, corrosion resistance and machinability. Used for turbine blades, pump shafts, valves, bolts, surgical instruments, and cutlery.

High-carbon martensitic stainless steel. Higher hardness than 410 (up to 56 HRC). The standard knife steel for European cutlery. Used for kitchen knives, pocket knives, surgical scalpels, machine blades, roller bearings, and valve components. Not weldable.

Nickel-bearing martensitic stainless steel with higher corrosion resistance than 410/420. Highest strength of the standard martensitic grades (up to 1100 MPa). Used for marine shafts, propeller shafts, high-strength fasteners, valves, and pump components.

High-carbon martensitic stainless steel with molybdenum and vanadium. Hardenable to 58+ HRC while maintaining moderate corrosion resistance. Used for cutlery, surgical instruments, valve components, bearings, and pump parts where hardness and corrosion resistance are both needed.

Highest-hardness standard martensitic stainless steel. Achieves 57-60 HRC — the hardest commonly available stainless grade. Excellent wear resistance from chromium carbides. Used for bearings, races, valve components, surgical instruments, high-end cutlery, and precision molds.

Soft martensitic (supermartensitic) stainless steel with good corrosion resistance and high toughness. Low carbon prevents embrittlement. The standard material for hydraulic turbine runners, pump impellers, compressor components, and offshore valves.

Japanese martensitic stainless steel — the higher-carbon variant of the 420 family (C 0.26-0.40%). Achieves HRC 50-55 after heat treatment. Very good corrosion resistance for a martensitic grade. THE budget knife/cutlery steel worldwide. Also used for surgical instruments, haircutting scissors, and industrial blades. ≈ EN X30Cr13 (1.4028) / Chinese 3Cr13.

Martensitic stainless for steam turbine blades and discs — 12Cr-3Ni-Mo-V. Higher Ni (2.5-3.5%) than X20Cr13 gives better toughness and corrosion resistance. V addition for creep strength at elevated temperatures. Used for LP/HP turbine blades, compressor discs, pump shafts, and valves in power generation. Service temperature to ~550°C.

Martensitic CrNi stainless — AISI 431. Best corrosion resistance of ALL martensitic stainless steels due to high Cr (15-17%) + Ni (1.5-2.5%). Hardenable to HRC 46-50. Used for shafts, bolts, valve stems, pump components, fasteners in marine/offshore environments. Also aerospace (WL4044) and medical instruments. Service to 400°C.

Basic martensitic stainless steel — 0.16-0.25% C + 12-14% Cr. Hardenable to HRC 48-52. THE workhorse martensitic stainless: cheap, available, and adequate corrosion resistance for mild environments. AISI 420 equivalent. Used for cutlery, surgical instruments, shafts, valve spindles, bolts, and turbine blades. Better corrosion resistance than X12Cr13 (1.4006/410) due to higher C and slight Cr advantage.

Supermartensitic stainless steel with high Ni and Mo. Excellent combination of high strength (up to 1000 MPa) and good corrosion resistance. Superior to CA6NM (1.4313). Used for offshore flow lines, subsea Christmas trees, hydraulic cylinders, and pump shafts.

High-carbon martensitic stainless steel — 0.9% C + 18% Cr. Achieves HRC 58-60 after hardening — among the hardest stainless steels. Better corrosion resistance than 440C (1.4125) due to higher Cr (17-19% vs 16-18%). THE premium European cutlery/surgical instrument stainless. Used for kitchen knives, surgical scalpels, razor blades, ball bearings in corrosive environments, and valve seats.