440B Stainless Steel - 1.4112 - X90CrMoV18 - ~SUS 440B

440B stainless steel is frequently used for plastic processing and for chemically aggressive molding materials. 440B is hardenable with a high chemical resistance, good polishability, high cutting edge retention and cutting performance. In some aspects, 440B exhibits similar behavior to tool steel.

It is corrosion resistant in mild atmospheres, organic materials, mild acidic environments and fresh water steam.

Corrosion resistance

440B’s corrosion resistance is similar to stainless steel 410. It is resistant to a variety of petroleum products, organic materials, fresh water as well as steam. For the highest corrosion resistance all surfaces should be free of foreign particles, lubricants, other coatings and scale. Parts should be cleaned and/or passivated after manufacturing.

Heat treatment

Annealing

Heat 440B uniformly to a temperature of 1550-1600°F (843-871°C), then cool slowly in the furnace.

Stress relieving

Heat uniformly to a temperature of 1202°F (650°C) and hold for 1-2 hours in a neutral atmosphere, then cool slowly in the furnace.

Hardening

Heat the material to a temperature of 1832-1976°F (1000-1080°C) and soak. Quench in warm oil or cool air and take care not to overheat the material, as it cannot obtain full hardness then.

Tempering

Heat the work piece to a uniformly to a temperature of 300-350°F (149-177°C) and soak for at least 1 hour to remove peak stresses and yet retain maximum hardness.

For our tempering diagram, please click here.

Hot working

Preheat the material to a temperature of 1400-1500°F (760-816°C), then heat slowly and uniformly to 1900-2150°F (1038-1777°C). Do not let the temperature drop below 1700°F (927°C) and reheat as and when necessary. Finish with cooling the material in the furnace, dry lime or ash and let the temperature of the work piece drop to ambient temperature before annealing it.

Cold working

440B has moderate cold formability, if annealed to maximum softness. As the material is sensitive to surface decarburization, it should be considered to use a protective atmosphere in heat treatments of finished work pieces.

Machinability

To a degree 440B machines like high speed steel, due to it high carbon content. As chips are tough and stringy, chip curlers and breakers should be used. For the best results, this material should be machined in its soft annealed condition.

Forging

Heat the work piece slowly and uniformly to a temperature of 2156°F (1180°C) and be mindful not to overheat the material as this might cause the loss of ductility and toughness. A temperature below 1850°F (1010°C) should be avoided, reheat the material if necessary. When finished forging cool slowly in the furnace, then anneal immediately after. Air cooling should be avoided as it may cause the material to crack.

Welding

440B is not typically recommended for welding, as it hardens in air and its high hardening capability. Should it be necessary to weld this material, similar fillers should be used to maintain the mechanical properties. Preheat the work piece to a temperature of 500°F (260°C) and do not let the material drop below this temperature at all times. Straight after welding the parts should be annealed at 1350-1400°F (732-760°C) for 6-8 hours. Do not let the temperature between welding the part and annealing it drop below 500°F (260°C). Annealing should be followed up with a slow furnace cooling to avoid cracking.

Grinding and polishing

For some applications grinding and polishing is a very important step. A high quality finish helps with the corrosion resistance in cutlery applications, care has to be taken not to overheat the work pieces as this can lower the corrosion resistance.