Alloy 15-5 PH

Alloy 15-5 is a precipitation-hardened alloy that offers high hardness and moderate corrosion resistance. It is a modified version of the older 17-4 alloy, engineered to deliver higher toughness—especially in the transverse (through-thickness) direction. Alloy 15-5PH is used in applications requiring excellent transverse strength and toughness, such as engine parts, aircraft components, and nuclear reactor elements.

Corrosion Resistance

The general level of corrosion resistance of 15-5 PH stainless steel exceeds that of types 410 and 431 and is approximately equal to that of 17-4 PH. This has been confirmed by laboratory testing in both strongly oxidizing and reducing environments, as well as under atmospheric exposure. In all heat-treated conditions, this alloy shows very little rust after 500 hours of exposure to a 5% salt spray at 35°C.

Physical Properties

Mechanical Properties

Welding

Precipitation-hardened steels can be welded easily using procedures similar to those used for 300-series stainless steels.

Heat Treatment

The key to the properties of precipitation-hardened stainless steels lies in the heat treatment process. After solution treatment or annealing, a single-step low-temperature aging process is applied to achieve the desired mechanical properties. Since this process is carried out at a relatively low temperature, it does not cause distortion and only results in minor surface discoloration. A slight shrinkage occurs during the aging process—approximately 0.05% for H900 condition and 0.10% for H1150.