Transient Liquid Phase Bonding of Geological Drill Pipe Using Two-step Heating Process

The geological drill pipes of 45MnMoB were joined by transient liquid-phase(TLP) two-step heating bonding process using amorphous filler in argon atmosphere.The microstructure and properties as well as the element distribution of the TLP bonding joints were investigated by means of SEM,material testing and EPMA.The results show that transient liquid phase bonding produced a homogenous joint with microstructure and composition equivalent to those of the base metal.The microstructure and properties of joint with one-step heating process was not as those of good as those of two-step heating process.The joint tensile strength obtained by two-step heating process (1 250/1 230 ℃) reached 890 MPa and the bending reached 180°.