HPM75

—High Hardness Wear-Resistant Non-Magnetic Mold Steel

Properties:

What material is HPM75? The non-magnetic steel grade HPM75 is a non-magnetic, high-hardness wear-resistant mold steel produced through special smelting processes. It maintains stable austenite in various states and has extremely low magnetic permeability. Therefore, it is most suitable for mold products requiring high wear resistance. Gas nitrocarburizing heat treatment can further enhance surface hardness and wear resistance, thereby extending the mold's service life. HPM75 non-magnetic stainless steel is prone to work hardening, so low-speed machining is recommended. The chemical composition of HPM75 non-magnetic steel is protected and not publicly disclosed.

Applications:

Non-magnetic steel HPM75 is suitable for manufacturing plastic and rubber molds requiring high wear resistance; producing mold components for semiconductor IC encapsulation; creating non-magnetic molds in the electronics industry; hot-work molds for industrial use at 700-800°C; non-magnetic cold-work molds, plastic and rubber molds; magnetic plastics and magnetic field forming molds; wear-resistant non-magnetic tools; mirror-polished molds, dust covers, TV filter plates, cosmetic cases, etc.; precision embossing molds, office automation equipment, automotive parts; EDM (electrical discharge machining) molds.

Characteristics:

Non-magnetic stainless steel grade HPM75 is a high-strength austenitic mold material. It maintains stable austenite in various states, and austenite is non-magnetic. Thus, HPM75 non-magnetic steel features ultra-low magnetic permeability, high high-temperature strength and hardness, excellent toughness and weldability, outstanding mechanical properties, and superior wear resistance. HPM75 non-magnetic steel is delivered in an age-hardened condition and requires no additional heat treatment. Its uniform structure makes it ideal for precision etching. HPM75 non-magnetic steel plates are available in thicknesses of 20-120mm, and non-magnetic steel bars in diameters of 20-160mm.

Heat Treatment Process:

The heat treatment for non-magnetic stainless steel HPM75 follows conventional solution and aging processes.

Heating temperature 1150-1170°C, heating time ≥8h, starting temperature 1100-1120°C, ending temperature ≥950°C, air cooling;

Holding temperature 1140-1160°C, heating time ≥8h, starting temperature 1080-1100°C, ending temperature ≥950°C, air cooling;

Quenching temperature

Tempering temperature

Quenching process

Annealing temperature 870-890°C, hold for 3-6h, furnace cool to below 500°C, then air cool. After annealing, HPM75 hardness is 28-30HRC, with a microstructure of fine-grained austenite + uniformly distributed granular carbides. High-temperature annealing improves the machinability of HPM75 non-magnetic steel.

Solution temperature 1150-1180°C, salt bath furnace hold 15-20min/mm, box furnace hold 30min/mm, water cooling. After solution treatment, HPM75 hardness is 20-22HRC, with a microstructure: austenite + undissolved primary carbides.

Aging temperature 650-700°C, aging time 15-20h, air cooling. After aging, HPM75 hardness is ≥45HRC.

Nitrocarburizing temperature 560-570°C, nitrocarburizing time 4-6h, surface hardness 950-1100HV, nitrided layer depth 0.03-0.04mm.