15-5PH stainless steel is a precipitation hardening stainless steel that is known for its high strength, corrosion resistance, and good toughness and wear resistance. It is commonly used in a variety of applications, including aerospace, oil and gas, and petrochemical industries. The “15-5” in the name refers to the chemical composition of the steel, which consists of 15% chromium and 5% nickel. The “PH” stands for precipitation hardening, which refers to the heat treatment process used to strengthen the material. 15-5PH stainless steel is a versatile material that is widely used in a range of applications due to its good combination of properties.
Heat treatment in the 900°F (482°C) range produces the highest strength, although it is slightly less than those of semi-austenitic alloys like S17700 or S15700. The latter precipitation hardening stainless steels generally require more steps to complete heat treatment. 15-5PH is generally better suited for plate applications than are the semiaustenitic alloys.
15-5PH stainless steel is often used for fasteners in the aerospace industry due to its high strength and corrosion resistance.
15-5PH stainless steel (S15500) is a variant of the older 17-4PH (S17400) chromium-nickel-copper precipitation hardening stainless steel.
Both alloys exhibit high strength and moderate corrosion resistance. High strength is maintained to approximately 600°F (316°C). This alloy is designated Grade or Type XM-12 in several specifications.
This Stainless Steel was designed to have greater toughness than 17-4PH, especially in the through-thickness (short transverse) direction. This improved toughness is achieved by reduced delta ferrite content and control of inclusion size and shape.
The composition and processing of 15-5PH is carefully controlled to minimize its content of delta ferrite, which is present in 17-4PH material. Inclusion control is done by consumable electrode remelting using the electro-slag remelting (ESR) process.
15-5PH is martensitic in structure in the annealed condition and is further strengthened by a relatively low temperature heat treatment, which precipitates a copper containing phase in the alloy. Like 17-4PH, 15-5PH Stainless requires only a simple heat treatment; a one-step process conducted at a temperature in the range 900°F (482°C) to 1150°F (621°C) depending on the combination of strength and toughness desired. A wide range of properties can be produced by this one-step heat treatment.