Effect of the welding process on microstructure, microhardness and residual stresses of capacitor discharge stud welded joint

Abstract Capacitor discharge (CD) stud welding is a common and fast connection technology. This paper presents an experimental and simulation study of the CD stud weld joint of 20 carbon steel plates. An optimized stud welding process was proposed based on microstructure, microhardness, and residual stresses of CD stud welded joint. The results show that a narrow weld seam with a widmanstaten structure is formed because of quick cooling. For the longer stud extension length, the width of the weld zone becomes wider and the microstructure becomes more uniform. With the increase of welding voltage and stud extension length, the microhardness increases and then decreases. The residual stresses are increased with the increase of welding voltage, while they are decreased with the increase of stud extension length. The optimized welding voltage and stud extension length should be designed to 90 V and 5 mm, respectively. This study will provide a great significance to the stud welding on site.