HPM75 non-magnetic steel

HPM75 is a non-magnetic, high-hardness, easy-cut plastic mold steel, which is produced by a special melting process. It is a non-magnetic, high-strength, austenitic, non-magnetic die steel in the HPM series steel. It remains austenitic stable under all conditions and has very low magnetic permeability. HPM75 non-magnetic steel has many mold characteristics such as high hardness, wear resistance, corrosion resistance, and non-magnetism comparable to stainless steel SUS304; therefore, it is most suitable for mold products that require high corrosion resistance and wear resistance. Gas nitrogen carbonitriding heat treatment can further improve the surface hardness and wear resistance, thereby increasing the service life of the mold.

Heat treatment process of HPM75 non-magnetic steel

The heat treatment process mainly includes: high temperature annealing process, solid solution softening process, and age hardening process; they are as follows:

(1) High temperature annealing process

The mold material has high hardness and poor machining performance; the purpose of high-temperature annealing of the mold is to improve the machining performance, eliminate forging stress, facilitate mold manufacturing and processing, and shorten the processing cycle; annealing process: annealing temperature 870-890°C, heat preservation 3-6h, Control the cooling rate from the annealing temperature to 500°C, the cooling time is not less than 6 hours, the hardness: 28-30HRC.

(2) Solid solution softening treatment process

The solid solution process is to dissolve material carbides into the matrix in preparation for age hardening treatment, while also improving cutting performance. It is also called softening treatment in production; equipment: box-type electric furnace (preheating), high-temperature salt bath furnace (solid solution) or box-type high-temperature electric furnace; solid solution softening process: when the margin is greater than 1.5-2mm, use high-temperature box-type The furnace is used for solid solution heating, heating temperature 1150-1180 ℃, salt bath furnace heat preservation 15-*20min/mm, box furnace heat preservation 30min/mm, water cooling, HPM75 solid solution hardness 20-22HRC, material microstructure: Austenitic body undissolved primary carbides.

age hardening process

The age hardening treatment after the mold manufacturing process is to disperse and deposit the carbides dissolved on the matrix on the matrix, thereby strengthening the matrix, improving hardness and wear resistance, and is also called hardening treatment in production; using a box-type electric furnace, aging temperature 650-700℃, aging for 15-20h, water-cooled or air-cooled, the hardness can reach 45-50HRC.