Investigation On Temper Bead Welding Technology Of SA508-3Steel For Nuclear Vessel

TBW (temper bead welding) is a novel repair welding technology which mayeliminate PWHT (post welding heat treatment).This technology has attractedextensive attention. TBW techniques have been used successfully for the weldingrepairof nuclear facility components by foreigners.Theimplementation condition,improvement mechanism and welding performances of TBW are lack of systematicresearch in China. Using the automatic TIG method, TheHAZmicrostructure andweld properties,weld bead geometry,welding process windows and implementationconditions of temper bead for SA508-3forged steel were discussedin this paper.The implementation conditions are obtained for SA508-3forged steel.Theimplementation criterion is presented for Tempering&Quenching Mode andTempering mode TBW. Thermal simulation experiment results showed thattheCGHAZ and IC-CGHAZ got mainly tempered sorbite after experiencing awelding thermal cycle which peak temperature is650℃or950℃whichsubsequently experiencing a welding thermal cycle of650℃.TBW can be realizedwith the precise control of weld bead geometry.The welding process window is established for Tempering&Quenching Modeand Tempering mode TBW of SA508-3forged steel. The wire feedrateand weldingcurrent improve the weld bead geometry configuration significantly. TBW can beachieved by changing the welding current and Wire feed ratewhile welding speedcan be regarded as fabrication weldability variables. Temper modes, Quenching andtempering modes can be achieved when the welding current is100A~200A.In order to confirm the research results, The microstructure and properties ofTBW compared with ordinary welding joint forSA508-3forged steel of60mmthickness. Both of Quenching&tempering mode and Tempering mode can improvethe microstructure and properties of heat affected zone effectively and obtain wellmatching of strength and toughness. Both TBW and ordinary welding joint can gettempered sorbite which has well performance. The impact toughness of CGHAZisequal to that of post weld heat treatment. Micro hardness of TBW HAZ is slightlyhigher than that of post weld heat treatment, but still meets the manufacturingrequirements.