铸钢表面镍基合金渗层的三点弯曲行为分析

Microstructure and Three Point Bending Behavior of Ni-based Infiltrated Layer on Cast Steel Substrate

采用铸渗技术在45钢表面制备了镍基合金渗层,对渗层的微观组织及弯曲行为进行了研究。结果表明:渗层组织致密,与基体呈冶金熔合,在渗层内部及渗层与基体的结合界面处无任何夹杂、气孔及微裂纹等缺陷,渗层主要由镍基固溶体、CrB以及Cr3Ni2组成;带有渗层的试样三点弯曲载荷-位移曲线上出现了三个峰值,在第一个峰值刚出现时渗层表面微裂纹开始萌生,随着第二个峰值的出现微裂纹微量扩展,在第三个峰值发生时渗层宏观断裂,但从载荷位移曲线上发现相同位移条件下其载荷依然大于基体,这说明渗层并没有完全破坏,第三个峰值时的载荷为0.88 kN,较相同条件下基体的载荷提高115%。

Ni-based alloying infiltrated layer was fabricated by vacuum infiltration casting process on 45 steel substrate. The microstructure and bending behavior of infiltrated layer were investigated. The results show that the microstructure of infiltrated layer is compact. There is a metallurgical fusion area at the interface between the infiltrated layer and substrate and no any inclusions, poles or micro-crack exist between the infiltrated layer and the interface. The main composition of the infiltrated layer is Ni-based solid solution, boride and intermetallic compound Cr3Ni2. There are three peaks on the load-displacement curve for the specimen with infiltrated layer. The micro-crack sprouts on the surface of infiltrated layer and extends imperceptibly when the second peak happens. The infiltrated layer ruptures when the third peak happens. The load of the specimen with infiltrated layer on curve is much larger than substrate on the same displacement condition, which can explain that the infiltrated layer is not all destroyed. The load is 0.88 kN for specimen with infiltrated layer at the third peak, which is improved by 115% compared with the substrate.