Alloy 17-7 PH SS Weldability

Stainless Steel 17-7PH® Precipitation Hardening Alloy is a semi-austenitic stainless steel which is austenitic in the annealed condition, however martensitic in the hardened condition. Stainless Steel 17-7 PH gives high strength and hardness, phenomenal fatigue properties, good corrosion resistance as well as minimum distortion upon heat treatment. It is effortlessly formed in the annealed condition, and then hardened to high strength levels by easy heat treatments. In the heat-treated condition, Type 17-7 PH provides magnificent mechanical properties at temperatures up to 900°F (482°C). It is corrosion resistance is superior to that of the hardenable straight chromium types. Corrosion resistance approximates that of the austenitic chromium-nickel stainless steels, in some environments. Using all common fusion and resistance techniques 17-7 is easily welded. Because of high Al content of this alloy 17-7 alloy is generally considered to have poorer weldability compared to more common PH grades (17-4 PH), which degrades penetration and improves weld slag formation during arc welding.

Applications
Stainless steel grade 17-7 PH is primarily used for applications requiring corrosion resistance, good strength, and mechanical properties up to 427°C (800°F) in operation. It is also commonly used for intricate parts due to its low distortion in heat treatment.

• Variety of springs and washers
• Chemical processing equipment
• Heat exchangers
• Power boilers
• Super heater tubes
• Components used in high-strength/high-temperature conditions