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Definition

Hot Isostatic Processing (HIP)
Application of high temperature and high pressure to remove internal porosity, consolidate powder for alloys, and diffuse bond.
Materials that can be HIPped
Titanium, beryllium, steel, aluminum, superalloys


Overview
Equipment used
Applications
Powder consolidation
Healing of casting defects
Diffusion bonding
Aerospace application
Pressures reach 200 Mpa
Temperatures reach 2000 degrees Celsius
Size of pressure vessel ranges from smaller than 4X12 up to 46X80


Powder Consolidation
Alloys are sometimes created using Powder Metallurgy
Alloys have trouble becoming chemically homogeneous
When they are allowed to form on their own they form large grains that do not mix as shown at right


Healing of Casting Defects
Casting defects such as internal pores causes weakness in materials
Dark spaces at right are internal pores
Voids act as stress risers
Leads to inaccuracy when predicting yield and ultimate strengths, scatter
With HIPping it is possible to change the material to a plastic state, collapse the voids, and bond the voided surfaces together (right)
The result is a stronger material that has less scatter with ultimate and yield strengths.
Accomplished though creep mechanisms and/or compressive plastic deformation


Diffusion Bonding

Components can be joined through Hot Isostatic Processing using Diffusion Bonding
Two materials undergo no more than a few percent macroscopic deformation
Important because welding and fastening produce larger deformation which leads to stress points and weakening of material

Major Aerospace Application
Turbine blades
Need for a blade that has cooling channels to encounter high temperatures
Using HIP it is possible to form a component from multiple components that are diffusion bonded
Can maintain low weight while being able to withstand high temperatures and stresses


Conclusion
Hot Isostatic Equipment
HIP applications
Heal defects
Diffusion bonding
Powder consolidation
Aerospace Application