Hot Isostatic Pressing (HIP) technology involves placing a product in a sealed container, filling it with an inert gas, and then sintering or densifying the product at very high temperatures (typically near the material's forging temperature) and pressures (usually between 100 and 140 MPa). This process allows for the sintering or densification of the product. For metallic materials, HIP can eliminate defects and achieve densification because, at high temperatures, metals exhibit very low strength and excellent plasticity. The external gas pressure causes plastic deformation in the metal around voids, allowing the metal to flow and fill the voids, resulting in a defect-free, dense structure.

The main parameters in the HIP process include heating temperature, gas pressure, holding time, and the type of gas used. The specific parameters vary based on the material's phase change behavior and high-temperature strength and plasticity. For instance, the HIP process for TC4 titanium alloy typically involves heating to 920°C at a pressure of 110-120 MPa for 1-2 hours using argon as the inert gas.

HIP technology is widely applied in various fields, including the sintering of cemented carbides, densification of refractory metals and alloys like tungsten, aluminum, and titanium, defect repair in products (such as 3D printed metal parts), near-net shaping of large and complex components, and the production of composite and special materials.

HIP can significantly enhance the mechanical properties of materials. For example, materials formed by laser SLM (Selective Laser Melting) or electron beam EBM (Electron Beam Melting) often see a decrease in strength and an increase in plasticity after HIP treatment. This change occurs because the rapid cooling rates in SLM processes lead to the formation of martensite, which decomposes during HIP annealing, thus reducing strength but increasing plasticity. Additionally, HIP treatment can alter the hardness of materials, typically resulting in a 5-10% decrease in hardness. Overall, HIP improves the toughness and resistance to fatigue crack growth of materials, making them more durable and reliable for various applications.