Effect of Temperature and Hold Time of Induction Brazing on Microstructure and Shear Strength of Martensitic Stainless Steel Joints
1Cr12Mo martensitic stainless steel is widely used for intermediate and low-pressure steam turbine blades in fossil-fuel power plants. A nickel-based filler metal (SFA-5.8 BNi-2) was used to braze 1Cr12Mo in an Ar atmosphere. The influence of brazing temperature and hold time on the joints was studied. Microstructure of the joints brazed, element distribution and shear stress were evaluated at different brazing temperatures, ranging from 1050 °C to 1120 °C, with holding times of 10 s, 30 s, 50 s and 90 s. The results show that brazing joints mainly consist of the matrix of the braze alloy, the precipitation, and the diffusion affected zone. The filler metal elements diffusion is more active with increased brazing temperature and prolonged hold time. The shear strength of the brazed joints is greater than 250 MPa when the brazing temperature is 1080 °C and the hold time is 30 s.