Improvement effect of Ni element on microstructure evolution and strength-plasticity of non-oriented silicon steel laser weld
摘要
Due to the presence of coarse columnar ferrite, rolling strip breakage occurs in the production of laser-welded silicon steel joints. Ni foil was used as an interlayer to carry out laser welding on 3-mm-thick non-oriented silicon steel. With the increase in the thickness of the Ni foil, the microstructure of the fusion zone (FZ) changed from coarse columnar ferrite to a duplex structure of ferrite and granular bainite, and finally transformed into austenite. The grain size of the FZ decreased from 197 to 58.5 μm. The average hardness of the FZ increased from 158.6 to 328.6 HV. The tensile strength increased from 293.6 to 505.8 MPa, the elongation increased from 2.6% to 22.3%, and the fracture position changed from the FZ to the base metal. The addition of Ni eliminated the coarse columnar ferrite and refined the grains, achieving the high strength and plasticity of the weld of silicon steel.