Bond Microstructure and Dissolution during Brazing of a Duplex Stainless Steel using a Ni-B-Cr Amorphous Alloy, MBF-80

摘要

Duplex stainless steels, containing an approximate 50:50 ratio of ferrite (δ) and austenite (γ) phases, are increasingly being used as an alternative to austenitic grades in a range of industries, including the oil and gas, petrochemical, pulp and paper, power generation, and pollution control industries. However, a loss of toughness and corrosion resistance has been reported in conventional fusion welding processes due to deterioration of the duplex microstructure and weld metal cracking (hydrogen cracking and solidification cracking). Brazing process eliminates the need for the application of considerable pressure during liquid-phase bonding and possesses unique possibilities, which include tolerance of stable surface oxides, a precise thermal cycle, high strength of the joint, and avoidance of heat-induced and aging cracking. The current study investigated the microstructural characteristics of the bond region and the base metal dissolution during brazing of the duplex stainless steel with a Ni-B-Cr amorphous alloy, MBF-80 (Ni- 15.2Cr-4.0B (wt.%)).