本文首先分析了金属材料的激光热处理技术的特点、分类以及国内外应用和研究现状，并着重介绍了薄板的激光相变硬化理论和技术。 涂层预处理是激光热处理的主要环节之一，本文系统地比较了几种预处理涂层对激光吸光性、气孔形成、强化层表面粗糙度及化学成份的影响，认为白色涂料是预处理涂料中较为理想的。在实验中采用了透射电子显微分析、X射线衍射、扫描电镜和硬度测量等手段，对薄板高碳钢激光热处理后的组织结构与性能特点及硬化机理做了探计，得出激光相变硬化主要原因是马氏体的晶粒细化和残余奥氏体含量的减小。 激光热处理后的切烟丝刀片在张家口卷烟厂的实际应用中获得较满意的效果，选用正交实验法优化后得出切烟丝刀片的最侍处理工艺为65Mn，矩形光斑尺寸为8*1mm，2000@,20mm/s,搭接 3mm。 本文还用有限差分法对激光热处理下的温度场进行了数值模拟，探讨了高能束的快速热传导问题。通过计算得到的输出功离密度、扫描速度、光斑类型等参数和实验结果比较吻合，证实了这种方法对录找材料最佳激光热处理工艺具有切实的指导意义。

The characteristic, classification, application and present situation of laser heat treatment were summerized in this thesis. its latest progress and the key problems of laser treatment on sheet steel were emphasized. The coating pre-treatment is one of the main links for lser heat treatment. After systematically comparing several effects of coating: absobtion of laser energy, gas hole formation, roughness and chemical composition, the white coating was considered as the best one. Many kinds of experiment methods were used in this research, such as: TEM, X-ray diffraction analyses, SEM observation etc. The studies of microstructure and properties of laser treated sheet steel showed that the grains were refined greatly and the retained austenite decreased significantly, which usually results in the hardening of materials. The laser hardened tobaco cutting blades had been tested in-situ with good result in Zhangjiakou Tobaco Factory and the best parameters were optimized by the orthogonal experiment method for the 65Mn steel as: P=2000W, V=20mm/s and size of laser beam=8*1mm. The finite differential method was used to simulate the temperature distribution of sheet steel in the laser treatment process, and the calcuated results were in good agreement with the experiments. This method is very useful for determining the best parameters of laser heat treatment.