TiAl/42CrMo感应钎焊接头力学性能及断裂特征

Mechanical properties and microstructure of TiAl/42CrMo joint induction brazed with Ag-Cu-Ni-Li filler metal

在Ar气保护条件下,采用Ag-Cu-Ni-Li钎料实现了TiAl基合金与42CrMo钢的感应钎焊。结果表明,在界面上有Ti3Al,AlCuTi,AlCu2Ti,Ag基固溶体、Ag-Cu共晶组织以及TiC等反应相生成。钎焊温度1000℃、保温30s,接头界面组织主要为Al-Cu-Ti的三元金属间化合物,拉伸测试中断裂发生在金属间化合物的内部;当钎焊温度890℃,保温时间30s时,接头室温抗拉强度、高温(400℃)抗拉强度分别达到309MPa,286MPa,拉伸测试中裂纹源于焊缝中金属间化合物粒子与Ag基体固溶体相界处,扩展到两侧母材界面的脆性相处发生断裂。

Induction brazing of TiAl to 42CrMo steel under the protection of Ar gas was carried out with a Ag-Cu-Ni-Li filler metal. The results show that Ti_3Al, AlCuTi, AlCu_2Ti, Ag-based solid solution, Ag-Cu eutectic and TiC phase occur at the interface of the brazed joint. When the joint was brazed at 1000 ℃ for 30 s, the interface is mainly composed of the Al-Cu-Ti ternary intermetallics;its strength is not very high; crack occurs in the Al-Cu-Ti ternary intermetallics. When it was brazed at 890 ℃ for 30 s, room temperature and elevated temperature (400℃) tensile strength of the joint is up to 309 MPa and 286 MPa, respectively. Crack occurs initially at the phase boundary of the AlCu_2Ti particles and the Ag-based solid solution, then expands to the reaction layers adjacent to the base metals and results in failure.