Effect of longitudinal magnetic field on grain growth of hollow stud welded joint

Abstract

Aiming at the defects of large diameter hollow stud welding such as arc blow and incomplete fusion,drawn arc stud welding with the longitudinal magnetic field was used to 30CrNi3MoV steel and Q235 stud. The grain growth process of joint was studied. With the assistance of longitudinal magnetic field, the arc action area on the end face of the hollow stud was increased, and the end face of stud was melted evenly. The solidification and crystallization process of molten pool was changed due to magnetic field stirring. Within a certain range, the microstructure of the joint is gradually refined and the size is homogeneous with the increase of magnetic field. But too large current can be attributed to the very coarse grain structure. Besides, the proportion of small angle grain boundary was decreased during appropriate magnetic field current, while the proportion of large angle grain boundary was increased. Meanwhile, preferred orientation of grains of the joints was changed due to the magnetic stirring.