激光热处理工件边界的保护及模拟研究

激光热处理应用研究中，当激光作用区临近工件边界时，防止边界熔化并让边界获得满意的热处理是必须认真处理的重要问题。实验研究表明，根据被处理工件的边界形状设计光阑并将光阑放在合适位置，可以有效地避免边界损伤并获得高质量的处理结果。为简化热作用研究，通常可以将被处理材料视为热物性参数为恒量的连续介质，而当处理工件的边界由相交平面边界构成时，可以通过引入适当的像热源来处理边界问题，因此，用这种热处理温度场的半解析计算方法可以满意地获得边界附近的瞬态温度场。提出了一种边界保护的简单方法，并利用激光热处理温度场的半解析计算方法作出证明。研究结果表明，合适选择边界保护宽度，不但能够有效保护边界，并能在边界附近得到深度均匀的硬化带。

Protection and Simulation of the Boundaries of a Workpiece of Laser Heat Treatment

In the application of laser heat treatment, when a laser beam is nearthe boundaries of a workpiece, it is important to avoid the melting dissolutionof the boundaries and obtain the satisfactory heat treatment. The experimentalresults indicates that designing the diaphragm in terms of boundaries′ shape ofa treated workpiece and then putting the diaphragm in the proper place, may avoidinjuring of boundaries effectively and obtain the treatment result with highquality. In order to simplify the research of heating action, treated material isusually regarded as the continuous medium whose thermal physical parameter isconstant. Moreover, when the boundaries of the treated workpiece are composed of the boundaries of intersectant planes, the appropriate image heat source can beused to deal with the problem of boundary. Therefore, instantaneous temperaturefield near the boundaries can be obtained satisfactorily by a semi-analyticnumeration of temperature field of laser heat treatment. To sum up, a simplemethod for boundary protection is proposed and proved by a semi-analyticnumeration of field of laser heat treatment in this paper. Results indicates thatchoosing the proper protective width of the boundaries properly, not only canprotect the boundaries effectively, but also can obtain the hardening band witheven depth near the boundaries.