B、Ti联合作用下堆焊层显微组织和生长机制

为了探究B、Ti联合作用下堆焊层的显微组织和生长机制,采用自行研制的铁基耐磨药芯焊丝,利用自保护明弧堆焊法制备了Fe-Cr-C-B-Ti堆焊合金.利用光学显微镜、扫描电子显微镜和X射线衍射仪对堆焊层的显微组织和生长机制进行了分析.结果表明,堆焊层中原位合成了Ti C和M_(23)(C,B)_6相.随着Ti元素含量的增加,显微组织中TiC相的数量逐渐增加并主要沿晶界分布.B元素含量的提高导致显微组织中Ti C相的数量变得不稳定.作为形核衬底的Ti C相可为M_(23)(C,B)_6相的附生生长提供条件.通过原位合成Ti C和M_(23)(C,B)_6硬质相可以提高堆焊层的综合性能.

Microstructure and growth mechanism of surfacing layer under combined effect of B and Ti

In order to investigate the microstructure and growth mechanism of surfacing layer under the combined effect of B and Ti, the Fe-Cr-C-B-Ti surfacing alloy was prepared with the self-developed iron-based wear resistant flux-cored wire through the self-protecting open arc surfacing method. The microstructure and growth mechanism of surfacing layer were analyzed with optical microscope, scanning electron microscope(SEM)and X ray diffractometer(XRD). The results show that both TiC and M₂₃(C,B)₆ phases are synthesized in an in-situ way. With increasing the Ti content, the quantity of TiC phase in the microstructure gradually increases, and the TiC phase distributes along the grain boundary. The increase of B content makes the quantity of TiC phase unstable. As a nucleation substrate, the TiC phase can provide the condition for the epiphytic growth of M₂₃(C,B)₆ phase. Through the in-situ synthesis of TiC and M₂₃(C,B)₆ hard phases, the comprehensive properties of surfacing layer can be improved.