Precipitation hardening stainless steels, like the martensitic types, can be strengthened by heat treatment. The mechanism is metallurgically different to the process in the martensitic types. This means that either martensitic or austenitic precipitation hardening structures can be produced. This family of stainless alloys utilizes a thermal treatment to intentionally precipitate phases, which cause a strengthening of the alloy. The principle of precipitation hardening is that a supercooled solid solution changes its metallurgical structure on aging. The advantage is that products can be fabricated in the annealed condition and then strengthened by a relatively low temperature treatment, minimizing the problems associated with high temperature treatment. Precipitation hardening stainless steel has high strength and relatively good ductility and corrosion resistance at high temperature. They reach these high strengths by precipitation of intermetallic compounds.