激光点状合金化对42CrMo钢疲劳裂纹扩展速率的影响  

Effect of laser spot alloying 42CrMo steel on the fatigue crack growth rate

作　　者：李正阳[1] 钟敏霖[1] 张红军[1] 张伟民[1] 刘文今[1] 

机构地区：[1]清华大学机械工程系先进成形制造重点实验室,北京100084

出　　处：《应用激光》2007年第1期1-4,共4页Applied Laser

摘　　要：裂纹倾向严重和搭接区软化是激光表面强化技术面临的两大难题,为此,提出了一种激光点状合金化方法:使预涂在基体表面的合金涂层或由喷嘴送入的合金粉,在激光小孔效应作用下,与基体形成混合熔池,得到合金化点。研究表明,大量规则分布、互不重叠的合金化区及其周围的相变硬化区从总体上降低了疲劳裂纹扩展速率,提高了材料的疲劳寿命。对疲劳裂纹断口的初步分析显示,相变硬化区对阻滞裂纹扩展其到了重要作用。To solve the problems of cracking and softening in overlapping passes by laser overlapped scanning surface hardening, a novel method named laser spot alloying was developed. The alloy powder, painted on the base or injected by nozzle, was melt with the base material by laser keyhole effect, then an alloying zone was formed. It is shown that a regular pattern distribution of scattered alloying zones which surrounded by phase transformation zone can retard the fatigue crack growth rate and improve the fatigue life. Fatigue fractographs analysis show that phase transformation zone plays an important role to retard the crack growth.

关 键 词：激光 合金化 疲劳裂纹扩展 断口 

分 类 号：TG405[金属学及工艺—焊接]