Microstructure and properties of the T91 TLP bonded joint with different interlayer

T91 steel pipes were joined by Transient Liquid-phase bonding process using BNi₂ 、Fe₇₈Si₉B₁₃ and FeNiCrSiB filler in argon atmosphere.The microstructures and properties,as well as the element distribution of the T91 TLP bonded joints with different filler metal were examined.The testing results showed that the tensile strength and bend strength at room temperature of the joint with FeNiCrSiB filler is equal to or even greater than that of the substrate.Boride are found in the joint region bonded by with Fe₇₈Si₉B₁₃ interlayer.The joint property with the BNi₂ interlayer is bad.It is considered that fracture of the joints is caused by these brittle intermetallics at interface and the discontinuity bond line microstructure.