Optimization of PWHT on Dissimilar Friction Welding for Piping Material of A105 to A312

A study on dissimilar friction welded joints were performed using 22 mm diameter tube-to-bar in forging bar steel(ASTM A105) to stainless pipe steel(ASTM A312) for piping materials. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, Virkers hardness surveys of the bond of area and HAZ, and macrostructure investigations. The specimens were tested as-welded and post-weld heat treated(PWHT). The tensile strength of the friction welded joints was increased up to 100â€ ï¼ of the A105 base metal under the condition of heating time(HT). Optimal welding conditions were n=2,000†rpm, HP=50†MPa, UP=100†MPa, HT=5†sec and UT=10†sec when the total metal loss(Mo) is 11†mm. The peak of hardness distribution of the friction welded joints can be eliminated by PWHT. Two different kinds of materials are strongly mixed to show a well-combined structure of macro- particles without any molten material and particle growth or any defects. In addition, the results of the radiological examination(RT) showed that there was no blowhole in the friction welding area. Key words: Friction welding, As-welded, Post weld heat treatment(PWHT), Base metal(BM), Heat affected zone(HAZ), Weld interface(WI), Radiographic examination(RT)