Stainless Steel Grade AISI 440B | EN 1.4112 | DIN X90CrMoV18

AISI 440B | EN 1.4112 | DIN X90CrMoV18 - martensitic stainless steel, belongs to high-carbon martensitic stainless steel. It is used for the production of stainless steel cuts, mechanical cutting tools and cutting tools, surgical instruments and blades, wear-resistant equipment parts, etc.

This steel is designed to provide stainless steel properties with excellent toughness. In some respects, it behaves similarly to tool steel. AISI 440B resists corrosion in moderate non-aggressive atmospheres, fresh water, ammonia, many petroleum products and organic materials, and some mild acidic environments.

Used in a hardened and tempered condition for good corrosion resistance. To ensure optimum corrosion resistance, the metal surface must be free of scale and foreign particles.

Heat treatment

Stainless steel is annealed at 843 °C - 871 °C followed by very slow cooling in a furnace. To perform hot working, materials must be heated to 760 °C, then slowly increased to 1038 °C - 1204 °C before continuing. The material must then be cooled slowly after working and cooled again at room temperature to anneal it as much as possible.

Cold processing

Steel can be cold worked with some difficulty by conventional cold working methods in the tempered condition.

Welding

Welding of this grade of stainless steel is generally not recommended because it has a tendency to air harden. When welding this grade of steel, the recommended heating temperature is 260 °C, and for post-weld treatment, the recommended temperature is 732 °C - 760 °C. Post-weld treatment should be carried out for 6 hours, and then the material should be cooled slowly in a furnace to avoid cracking. Similar high heat inputs and appropriate filler metal should be used in the work.

Mechanical processing

Best machined in annealed condition. Chip scrapers are used to machine hard, fibrous stainless steel chips. Ceramic or carbide tools are best suited for this grade of stainless steel.

Tempering and hardening

For tempering, AISI 440B steel must be maintained at a temperature of 148 °C. Stainless steel is heated to 760 °C, soaked to 1010 °C and finally cooled in oil or air.

The maximum hardness that can be achieved is 57 - 59 HRC (578 - 600 HB).

Physical properties