Abstract: The distribution of temperature, stress and strain of titanium alloy Ti-6Al-4V thin sheet were studied with numerical simulation and experiment during conventional gas tungsten arc welding and gas tungsten arc welding with trailing spot heat sink behind welding arc, also named dynamically controlled low stress no-distortion gas tungsten arc welding, the influences of heat sink on temperature, stress and strain fields were investigated, the stress and distortion controlling mechanism of dynamically controlled low stress no-distortion technique was discussed. The results show that, during dynamically controlled low stress no-distortion gas tungsten arc welding, the saddle shape temperature field is formed due to the intense cool effects of heat sink, there exists the lowest temperature in the heat sink applied region. High tensile action of metals is generated by sharp cooling of the heat sink applied region, which decreases the compressive plastic strains in heating process and increases the tensile plastic strains in cooling process within and near the weld. The incompatible strains in the joint decrease and the residual stresses reduce. The simulation results are in good agreement with the experimental results, which proves the effectiveness of DC-LSND technique and the validity of the finite element model.
Role of heat sink in gas tungsten arc welding with trailing spot heat sink for titanium alloy
Abstract:
The distribution of temperature, stress and strain of titanium alloy Ti-6Al-4V thin sheet were studied with numerical simulation and experiment during conventional gas tungsten arc welding and gas tungsten arc welding with trailing spot heat sink behind welding arc, also named dynamically controlled low stress no-distortion gas tungsten arc welding, the influences of heat sink on temperature, stress and strain fields were investigated, the stress and distortion controlling mechanism of dynamically controlled low stress no-distortion technique was discussed. The results show that, during dynamically controlled low stress no-distortion gas tungsten arc welding, the saddle shape temperature field is formed due to the intense cool effects of heat sink, there exists the lowest temperature in the heat sink applied region. High tensile action of metals is generated by sharp cooling of the heat sink applied region, which decreases the compressive plastic strains in heating process and increases the tensile plastic strains in cooling process within and near the weld. The incompatible strains in the joint decrease and the residual stresses reduce. The simulation results are in good agreement with the experimental results, which proves the effectiveness of DC-LSND technique and the validity of the finite element model.
Fig.6 Transversal direction distributions of residual longitudinal stress(a) and residual plastic strain(b) under conventional and DC-LSND welding conditions (a)—Residual stress; (b)—Residual plastic strain