Water cooling keyhole gas tungsten arc welding of HSLA steel

Keyhole gas tungsten arc (K-TIG) welding with water cooling system was used to weld high-strength low-alloy steel of mid-thickness (thickness ranging 6–13 mm). Q345 plates of 8-mm thickness were jointed in a single pass without filler metal. The weld properties, including mechanical properties and microstructure, were analyzed. The maximum tensile strength of the weld was similar with that of the base metal, while the elongation and impact property of the weldment were decreased compared with the base metal. The numerical simulation result revealed that water cooling method used in K-TIG welding is greatly helpful in reducing the volume of the welding pool due to the enhanced cooling effect. Additionally, improved holding power of the welding pool can be obtained due to the increased surface tension.