Machinability

Machinability of stainless steel grade 17-7 PH is rated at 75 % of B1112. On machining, this alloy displays long gummy chips and requires chip breakers. It is recommended that slow speeds and constant feeds while machining will provide excellent results.

Heat Treatment

For heat treating stainless steel grade 17-7 PH, three important steps need to be carried out – austenite conditioning, cooling to transform the austenite to martensite, and precipitation hardening to condition TH 1050 or RH 950.

Forming

Forming characteristics of stainless steel grade 17-7 PH are similar to stainless steel grade 301. For radical forming operations, intermediate annealing may be required.

Welding

Common arc and resistance methods can be used with stainless steel grade 17-7 PH. It is recommended that during fusion welding inert gas shielding should be performed to reduce the oxidation of aluminum during the process.

Annealing

Annealing of stainless steel grade 17-7 PH is performed at 1066°C (1950°F) for 3 min for every 0.1 inch (2.5 mm) of thickness, and then air cooled.

Aging

Stainless steel grade 17-7 PH is solution annealed at 1177°C (2150°F) for 4 h and air cooled. Same step is performed at 1079°C (1975°F) for 4h and air cooled, then at 843°C (1550°F) for 24h and air cooled, and at 760°C (1400°F) for 16h and air cooled. This completed the precipitation hardening process. For excellent results and performance, the material should be clean and free from scale and impurities.