Laser weldability of Zr-2.5Nb alloy to AISI 410 stainless steel with Ni filler.

The nickel interlayer improved the laser weldability of Zr-2.5Nb to AISI 410 stainless steel. The fusion zone contained a large amount of refined and tough dendritic γ-Ni(Fe, Cr) solid solution (182 ∼ 268 HV), while the brittle Zr(Fe, Cr) 2 intermetallic compound (1171 ∼ 1460 HV), which was the main phase as the result of direct welding of Zr-2.5Nb to SS410 as well as the source responsible for the welding cracks, disappeared. Only limited quantities of Zr 2 (Ni, Fe), Zr 7 Ni 10 (and/or Zr 2 Ni 7 ) intermetallics were present mainly in the form of thin layers (less than 200 μm thick in total) near the fusion interface with Zr-2.5Nb. Those Zr-Ni based intermetallics showed relatively higher toughness and lower hardness (301 ∼ 497 HV) than the brittle Zr(Fe, Cr) 2 , which reduced the overall cracking sensitivity of the laser-weld. [ABSTRACT FROM AUTHOR]