Effects of boron and silicon on microstructure and isothermal solidification during TLP bonding of a duplex stainless steel using two Ni–Si–B insert alloys

Abstract

The influence of B and Si on microstructure and isothermal solidification during transient liquid phase (TLP) bonding of a duplex stainless steel using MBF-30 (Ni–4·5Si–3·2B, wt-%) and MBF-35 (Ni–7·3Si–2·2B, wt-%), was investigated. Based on experimental studies, the formation of Ni₃B within the joint centreline is dependent on B content; the morphology of Ni₃Si is dominated by Si concentration. There was a deviation between the times for complete isothermal solidification obtained by the experiment and the conventional TLP bonding model. Isothermal solidification of the liquid dependent on different solidification regimes is suggested to be a controlling factor contributing to the change in the rate of isothermal solidification observed using the two filler metals.

Keywords:

• Duplex stainless steel
• TLP bonding
• Brazing
• Ni–Si–B insert alloy
• Isothermal solidification

One of the authors (Xinjian Yuan) gratefully acknowledges the financial support provided by a national study abroad project for postgraduates of key, high level universities in China. The authors are also grateful for financial support from the National Core Research Center program of the Ministry of Science and Technology and the Korea Science and Engineering Foundation (No. R15-2006-022-02004-0).