HIP Treatment

NovaCast provides high integrity cast components to some of the most demanding industries. Porosity and other casting defects are common with cast metals but these can be significantly reduced or eliminated entirely by post-casting treatments, such as Hot Isostatic Pressing (HIP). The HIP process uses elevated heat and gas pressure to densify metals and eliminate internal microporosity through plastic deformation and diffusion bonding.

NovaCast typically uses the HIPing process to produce high integrity, gas-tight valve bodies for use in specialist applications but the process is also commonly used in aerospace structural components, automotive engine parts, petrochemical processing equipment, tooling and die parts, and many other applications where enhanced mechanical properties are required.

NovaCast can use the HIP process to treat most metals including aluminium, stainless steel, and superalloys as well as alloys of aluminium, titanium, chromium, copper and iron.

Benefits of HIP treatment include:

  • Removal of internal defects, such as porosity, and shrinkage defects, such as creep voids and internal cracks.
  • Consistency is improved throughout the casting with less variation in mechanical properties.
  • Tensile and proof strengths can often be improved by about 5% and ductility by 50% although this will vary with other parameters.
  • Fatigue properties are considerably improved bringing cast properties close to the wrought equivalent.
  • Impact strength, toughness and machined surface finishes are all improved.
  • Enhanced mechanical properties allow geometry design modifications that can reduce component weight, size and cost.

The HIP Process

The HIP process involves the placement of castings into a pressurised, enclosed, high temperature furnace for a prescribed length of time. Within the furnace, inert gas (typically argon) is used to exert uniform isostatic pressure on the castings. This combination of heat and pressure allows material to flow into internal pores where diffusion bonding occurs, eliminating the defect. The purity of the inert gas ensures that the chemical composition of the casting remains unchanged.