Effects of post weld heat treatment on friction welded duplex stainless steel joints

In the present work, the effects of post weld heat treatment (PWHT) on friction welded UNS S31803 duplex stainless steel samples at three different temperatures namely 1080 °C, 1150 °C and 1200 °C followed by water quenching were studied. Microstructural evaluations such as volume fraction of austenite/ferrite, grain size measurements, SEM-EDS, TEM and microhardness aspects were carried out. The volume fraction of ferrite to austenite ratio was balanced at 1080 °C. Ni element is more effective in controlling the dual phase balance. Finer grains were obtained at 1080 °C due to recrystallization effect. Microhardness was affected by reduction of ferrite percentage. Dual phase presence and absence of precipitates were conformed through XRD and TEM which follow Kurdjumov-Sachs relationship. Under the following: heating pressure: 40 heating time: 4 upsetting pressure: 80 upsetting time: 2 (Experiment no. 5) on PWHT at 1080 °C, the balance of dual phase ratio, finer grains and increased microhardness were obtained.