The Influence of Powder Layers Intervention on the Microstructure and Property in Brazing Joints of Titanium/Steel

Abstract

Brittle intermetallic compounds in brazing joint of titanium alloy and stainless steel easily make the weld organization and mechanical properties worsen. In order to solve the above problem, tests were performed to compare the different types of metal powder layers in the brazing joints of titanium/steel. On this basis, the mechanical property and microstructure of these joints were explored as technology parameters were changed and different powders were added. The test results show that the elements such as Nb, Cr, V in the powder layer participate in the metallurgical reaction of joints so that the newly born phase appears in joints. At the same time, the microstructure of joints was transformed into the mixture of metal powder particles, solid solution, solder, and various brittle phases. This makes mechanical properties of joints clearly better than the joint of non-powder layer. At the joints where Cr powder layer was added beside the stainless steel and Nb–V powder layer, was added beside the titanium alloy simultaneously, and their maximum shear strength reached 193 MPa, which is more than twice of the joints without metal powder layer. It is the main reason of the improving mechanical property that newly born phase of Cr–Fe, Ti–V replace pervious Fe–Ti and Cu–Ti IMCs in microstructure of the joints.