低碳钢表面激光相变硬化研究  

Research of laser transformation hardening on mild steel

作　　者：张培磊[1] 丁敏[1] 姚舜[1] 姚成武[1] 

机构地区：[1]上海交通大学上海市激光制造与材料改性重点实验室(筹),上海200240

出　　处：《激光技术》2009年第6期586-589,共4页Laser Technology

基　　金：国家科技部国际科技合作资助项目(2006DFB52680);上海市科委国际合作资助项目(061107030)

摘　　要：为了研究不同激光功率及不同的冷却条件下,激光相变硬化处理对低碳钢表面性能和组织的影响,采用激光表面相变硬化方法,在低碳钢表面获得了比原先母材硬度高100HV～150HV 的硬化层,采用金相显微镜分析了激光处理区的组织,且用显微硬度计测量了单道扫描时的纵向和横向的硬度分布。研究发现,激光作用区主要是低碳板条马氏体与未转变的索氏体甚至屈氏体、回火索氏体组织。搭接区组织均为细小的马氏体及中间分布着索氏体组织;由于10CrNiMo 钢含碳量较低和碳扩散系数不同的原因,其最高硬度层并未在表面形成,而是形成在次表层。在软化区,前一道扫描形成的马氏体受到回火作用,原先固溶在马氏体中的碳析出,形成了回火索氏体,降低了硬度。结果表明,激光相变硬化工艺可以将10CrNiMo 钢的表面硬度提高100HV～150HV 左右,且表面保持很好的韧性,若想进一步提高其表面硬度,还需采取熔覆等其它工艺。The effect of laser transformation hardening on the surface property and microstructure of mild steel 10CrNiMo under different laser power and cooling conditions was studied. A hardened layer on the surface of the mild steel was obtained whose microhardness is 100HV - 150HV higher than that of the original mild steel. The microstructure of laser processed zone was observed with a metallographie microscope and the hardness of laser processed layer was measured with a mierohardness tester. The results showed that the quench zone consisted of martensite, retained sorbite, troostite, tempered sorbite and that the microstrcture in the lap zone was martensite and some sorbites locating in the middle of martensite. Because of the lower carbon content of steel 10CrNiMo and different carbon diffusion coefficient, the highest hardness did not appear on the surface but in the subsurface. In the softened zone, because the martensite produced by the first laser scanning was tempered by the second laser beam,the carbon in the martensite separates and changes into temper sorbite. Microhardness of lap zone declined due to the temper of second laser scanning. Laser transformation hardening can improve the surface hardness 100HV - 150HV higher and keep good tenacity. Furthermore, laser cladding can be taken to increase the hardness more evidently.

关 键 词：激光技术 激光相变硬化 低碳钢 显微硬度 

分 类 号：TG156.99[金属学及工艺—热处理]