Hot Isostatic Pressing (HIP)
HIP tends to use the coarser fraction of as-atomised powders, typically in the region of 45 – 106µm. Even the use of larger-sized powders with accompanying coarser microstructures still provides a beneficially refined structure in the final port compared to those of cast and wrought components.
However the use of coarser powders reduces the surface area of the powder in a given weight therefore reducing the amount of oxide a powder attracts during atomisation and when exposed to air.
This and careful control of melt chemistry prevents lines of weakness between the “prior particle boundaries” in the HIPped component, giving rise to better toughness and fatigue life in the product.
MPP, by careful selection of melt feedstock melting refractories and atomising parameters is able to minimise harmful oxides and tramp elements in the powder it produces.
