Studies on characteristics of temperature field during GTAW with a trailing heat sink for titanium sheet

The characteristics of temperature field have been studied numerically and experimentally for a titanium alloy sheet when welded with an improved gas tungsten arc welding method, in which a trailing spot heat sink is introduced to control the welding stress and distortion. The impinging jet model is employed to describe the intense heat transfer between the cooling media and the top surface of the workpiece. By comparing this improved technique to the conventional gas tungsten arc welding (GTAW) process, the influence of the spot heat sink is investigated. Results show that a low temperature region exists where the heat sink is applied; a saddle backed temperature field, with the lowest temperature at the centre and higher temperatures at both sides, is formed during the improved welding method; and the time that the metal spends at high temperature is shortened in the improved welding process. Experimental measurements of the thermal histories compare well with the calculations, which prove the validity of the finite element model and the impinging jet heat transfer model in simulating the gas tungsten arc welding process with a trailing heat sink.