Ideal method for consolidation of powders of nickel and cobalt base super alloys, tool steels, maraging steels, titanium alloys, refractory metal powders, cermets. It has got variety of applications including bonding of dissimilar materials, consolidation of plasma coatings, processing hard and soft magnetic materials etc.
- HIP is the application of pressure at elevated temperatures to obtain net or near net shape parts from metal, ceramic, cermet powders.
- HIP unit consists of a pressure vessel, high temperature furnace, pressurizing system,controls and auxiliary systems (material handling, vacuum pumps, metering pumps).
- The pressure vessel is made of low alloy steel. Its function is to heat the powders while applying uniform gas pressure on all the sides. Furnaces are of radiation or convection type heating furnaces with graphite or molybdenum heating elements. Nichrome is also used. The furnace heats the powder part, while pressurizing medium (a gas) is used to apply a high pressure during the process. Generally, argon, nitrogen, helium or even air is used as pressurizing medium.
- The pressurizing gas, usually argon, is let into the vessel and then a compressor is used to increase the pressure to the desired level. The furnace is then started and both temperature and pressure are increased to a required value.
HIP presses are available in diameters up to 2m with pressures ranges from 40 to 300 MPa with temperature range from 500 to 2200 °C. The processing time can last up to 4 hours depending on the material and size of the part.
- during HIP, the pores are closed by flow of matter by diffusion and creep, but also bonded across the interface to form a continuous material.
- Commonly used heating elements: Kanthal heating element – up to 1200 °C; Molybdenum heating element – 1200 to 1700 °C; Graphite heating element – 2000 to 2600 °C
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