What Does Hot Isostatic Processing (HIPping) Mean?
Hot isostatic processing (HIPping) involves the application of high gas pressure at an elevated temperature to components in order to completely remove internal porosity and voids.
This process is an excellent option for the improvement of a wide variety of materials, such as:
Using this process, voids within a casting can be reduced or eliminated and encapsulated powders can be consolidated to create fully dense materials. Dissimilar materials can also be bonded together to manufacture unique, cost-effective components.
Hot isostatic processing is also known as hot isostatic pressing.
Corrosionpedia Explains Hot Isostatic Processing (HIPping)
Hot isostatic processing technology was developed during the 1950s, initially as a means of diffusion bonding nuclear reactor components and removing porosity in hard metals, such as tungsten carbide. However, commercial use is now mainly focused on the densification of high-performance castings and consolidation of metal powders, the aerospace industry being only one of a wide range of industries to utilize the process.
HIPping involves the simultaneous application of high pressure and temperatures on materials through the medium of a pressurizing gas to completely remove internal porosity and voids, improving the material's mechanical properties and workability. Pressure is applied to the material from all directions, hence the term "isostatic."
The HIP process falls into three categories:
- Powder Metallurgy
- Composites, diffusing two like or unlike metals together
Primary applications include:
- Reduction of microshrinkage
- Consolidation of powder metals, ceramic composites, plastics
- Metal cladding
- Fabrication of metal matrix composites
Benefits of HIPping include:
- Stabilizing a material
- Removing residual stresses
- Eliminating voids and occlusions
The process homogenizes an alloy and in most cases, the properties of the material are enhanced, providing greater stability and wear characteristics. The HIP process can produce materials from metallic compositions that are difficult or impossible to forge or cast.