Effects of TLP bonding temperature on the microstructurs and properties of T91 joint with two-step heating process

A modified 9Cr-1Mo(martensitic T91 steel pipes) were joined by transient liquid-phase bonding with two-step heating process using FeNiCrSiB(A) filler in argon atmosphere.The tensile strength and bend properties of the TLP joint were examined at room temperature.The microstructures and the element distributions as well as hardness of the joints with TLP two-step heating process were also investigated by means of SEM, EPMA and microhardness meter.The testing results indicate that the temperature gradient of TLP two-step heating process has prodigious effect on microstructures and properties of the joint.The microstructures and properties of TLP joint are best with the process at 1 270℃ heating for 0.5 min, and at 1 230℃ isothermal for 3 min.