Study on local heat transfer of 18Ni maraging steel after electron beam welding

This study is concerned with the improvement of the strength of 2401 MPa maraging steel weldments. In order to increase the strength of the weld metal by 10%, solidified structures of weld metal are controlled by electron-beam scanning welding. By subjecting the joint to local aging treatment, ultimate strength of the base metal is increased by approximately 96%. The fracture appearance show small reinforced dimples. Residual austinite uniformly distributes at the boundaries of cellular dendrites. Ti and Mo segregate at the boundaries and form reinforced phases consisting Ni and Ti or Ni and Mo. A new opinion that electron-beam high-speed isothermal heating local aging treatment strengthens austinite but not martensite is emphasized.