17-7 PH is a chromium-nickel-aluminum semi-austenitic precipitation-hardening stainless steel developed to combine high mechanical strength with good corrosion resistance and excellent fatigue properties.

The alloy can be readily formed in its relatively ductile condition before subsequent conditioning and precipitation-hardening treatments develop the required high strength and hardness. Aluminum plays an important role in its precipitation-hardening response.

One of the major advantages of 17-7 PH is its excellent spring performance and fatigue resistance. It is particularly suitable for thin sections and precision-formed components subjected to repeated mechanical loading.

17-7 PH is commonly supplied as sheet, strip, coil and wire rather than being focused primarily on heavy forgings. Typical applications include springs, diaphragms, bellows, retaining rings, clips and aerospace precision components.