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在 4 5 #钢基底上进行了铁基合金和铁基合金加TiO2 的激光熔覆对比实验。采用渗透法观察熔覆层表面裂纹 ,利用金相显微镜和扫描电镜观察熔覆层横断面的显微组织 ,使用X射线衍射仪对熔覆层进行物相分析 ,并测试了熔覆层横断面的硬度分布和熔覆层的摩擦磨损性能。结果表明 ,在一定的工艺条件下 ,添加适量的TiO2 ,可以获得成形良好、无裂纹、组织致密均匀、耐磨性好的高质量铁基激光熔覆层。适量的TiO2 可使涂层共晶体数目增多且分布均匀 ,组织细化 ,裂纹消失 ,在降低涂层裂纹敏感性的同时仍保持涂层的硬度和耐磨性不降低。TiO2 对铁基熔覆层性能改善的原因是 :适量TiO2 的加入 ,在涂层中可形成Cr13Fe35Ni13Ti7金属间化合物 ,熔覆层组织由亚共晶组织转变为性能较好的伪共晶组织 ,且由于高熔点的Ti硼化物的析出 ,提高了形核率 ,使组织颗粒细化、均匀。
Laser cladding experiments of Fe-based alloys and Fe-based alloys with TiO2 were carried out on 45 steel substrates. The surface cracks were observed by infiltration method. The microstructure of the cladding layer was observed by optical microscope and scanning electron microscope. The phase of the cladding layer was analyzed by X-ray diffractometer. The cross-section of cladding layer The hardness distribution and the friction and wear properties of the cladding. The results show that high quality iron-based laser cladding layer with good forming, no crack, dense and uniform structure and good wear resistance can be obtained by adding proper amount of TiO2 under certain process conditions. Appropriate amount of TiO2 can increase the number of coating eutectics and uniform distribution, refine the structure, the cracks disappear, while reducing the sensitivity of the crack coating while still maintaining the hardness and wear resistance of the coating does not decrease. The reason for the improvement of the performance of the iron-based cladding layer by TiO2 is that when a suitable amount of TiO2 is added, a Cr13Fe35Ni13Ti7 intermetallic compound can be formed in the coating, and the microstructure of the cladding layer changes from hypoeutectic structure to pseudo-eutectic structure with better performance Due to the precipitation of Ti boride with high melting point, the nucleation rate is increased and the grain size of the structure is refined and uniform.