Stainless Steel Grade AISI 440A | EN 1.4109 | DIN X70CrMo15

AISI 440A | EN 1.4109 | DIN X70CrMo15 is a martensitic stainless steel with a high carbon content (high carbon stainless steel) developed to provide properties for maximum hardness and strength. It is magnetic both in the annealed and hardened condition. This grade is classified as a tool stainless steel.

Maximum hardness and corrosion resistance are only available in quenched and stress relieved conditions, so the alloy is not used in the annealed and tempered condition.

Mechanical processing

Stainless steel grade AISI 440A is easily machined in annealed condition. For machining, it is recommended to use carbide or ceramic tools. Chip-lamas allow easy processing of hard fibrous chips.

Welding

Since this steel has a tendency to air harden, welding is not performed. However, if welding is necessary, the steel should be preheated to 260 °C and post-weld treated at 732 °C - 760 °C for 6 hours. This is followed by slow cooling in a furnace to prevent cracking.

Hot processing

Stainless steel is annealed at 843 °C - 871 °C and then cooled very slowly 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. Finally, it must be fully annealed.

Tempering and hardening

For tempering, AISI 440A steel should be held at 148 °C. Similarly, for curing, the material should be slowly heated to 760 °C, then held at 1010 °C and finally cooled with air or oil.

Physical properties

Mechanical properties

Application

Stainless steel grade AISI 440A | EN 1.4109 | DIN X70CrMo15 is widely used in the following areas:
- cutlery;
- bearings;
- measuring blocks;
- moulds and dies;
- valve components;
- turbine components;
- medical instruments;
- aircraft structural parts;
- knives and measuring instruments.