Abstract:
Objective The aim is to investigate the effect of online electromagnetic induction heating power during laser-arc hybrid welding on the microstructure and mechanical properties of normalized non-oriented high grade silicon steel welded joints.
Methods The microstructure and mechanical properties of welded joints are researched by using methods such as EBSD, SEM and hardness testing.
Results The microstructure of weld zone is mainly composed of ferrite and upper bainite. Increasing heating power leads to increase of grain size and width of weld zone, also the weld zone is penetrated deeper by deposited metal that expands the formation range of upper bainite. The hardness of weld zone (about 280 HV) is higher than those of heat affected zone (about 185 HV) and base metal (about 200 HV). From top to bottom of weld zone in thick direction, the increase of Si element content and the decrease of grain size are the main reasons for the gradual increase of hardness. The increase of Si element content from the center line to the edge of weld zone leads to the “V” shape distribution of hardness in the weld zone cross section.
Conclusion With the increase of heating power, the hardness of overall weld zone increases, the tensile strength of welded joint increases, and the plasticity decreases. The tensile fracture mode is typical transgranular cleavage fracture.