Microstructure and Mechanical Properties for TIG Welding Joint of High Boron Fe-Ti-B Alloy

The hot rolled plates of high boron Fe-Ti-B alloys were butt-welded by gas tungsten arc welding (TIG) using base metal as the filler. The microstructures of the TIG weld joints were analyzed. The results indicate that the welding quality of the high boron Fe-Ti-B alloys is very good, there are no obvious defects such as cracks, lack of fusion, incomplete penetration and strip defects in the butt weld joints. The microstructures of the weld metal and the heat affected zone are different from that of the base metal significantly. However, the micro-zone composition analysis indicates that the composition of the TIG weld joint is very uniform. Tensile tests were carried out on TIG welded joints after the post weld heat-treatment. The result shows that the welds have slightly higher yield strength (YS), and lower ultimate tensile strength compared to those of the base metal. However, the tensile properties reach a high level. The tensile strength of the high boron Fe-Ti-B alloys is higher than 580 MPa, and the yield strength is higher than 400 MPa.