【作者】 何静波；

【导师】 黄因慧；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2006， 硕士

【摘要】 喷射电镀是一种高速电沉积工艺,具有选择性好的优点,适合局部电镀;激光重熔是一种新型的材料加工与表面改性技术,可以在低成本钢板上制成高性能表面,代替大量的高级合金。结合两种工艺的特点,对喷射电镀镀层进行激光重熔,通过优化的重熔工艺参数获得较均匀、致密性好、与基体结合性强的重熔层。本文采用数值模拟方法,对连续移动三维瞬态喷射电镀层激光重熔温度场的规律及其应用进行了研究。(1)根据喷射电镀层激光重熔过程的实际情况,确定采用数值模拟的方法研究喷射电镀层激光重熔温度场的基本过程,通过对有限差分法和有限单元法的比较确定选择有限单元法作为数值模拟的计算方法。(2)建立移动激光高斯热源作用下三维瞬态温度场的数值模型,在ANSYS平台上采用APDL语言编制了相应的计算机程序。用该模型对喷射Ni镀层激光重熔的温度场进行了分析计算,并在相同的工艺参数条件下将计算结果与试验结果相比较来验证并修正计算模型。结果表明所得喷射电镀层激光重熔温度场模拟结果与实际测量情况吻合良好。(3)利用该数值模拟分析方法得到的计算结果预测熔池形状、热影响区的情况,分析了在不同区域内组织形貌形成的成因,以及镀层厚度、致密性、结合性和激光重熔的工艺参数等对温度场分布的影响。结合材料的微观组织形貌对于拉伸、腐蚀等实验结果进行分析,得出使重熔温度场分布较为合理的激光重熔工艺参数,对喷射电镀层激光重熔试验进行指导。更多还原

【Abstract】 Jet electroplating is one of high speed electrodeposition processes and can be applied to part electroplate because of its good selectivity quality. Laser remelting is a new kind of technology on material process and surface modification. It can be used in manufacturing good capability on the armor plate with low cost and instead of high-class alloy. In order to obtain the coating which is symmetrical, compact and joined together with substrate, process parameters of laser remelting must be optimized.In this paper, numerical simulation method is used in studying the regular of transient temperature field of 3D moving jet electroplated coating laser remelting and its appliance.(1) Accoding to natural conditions of jet electroplated coating laser remelting, numerical simulation method which is used in research temperature field of jet electroplated coating laser remelting procedure is confirmed. By comparing Finite Diffence Method with Finite Element Method, Finite Element Method is choosed as a calculation method of numerical simulation.(2) Computational model is established for analysis of 3D laser cladding temperature field caused by moving Gauss distributing heat source. The program prepared by the APDL language is attached to the commercial software ANSYS. And this model is used in computing and analysising the temperature field of Jet electroplated nickel coating which is remelted by laser. Then computational model is modifid and verified by comparing calculated result with experimental result. Under the same laser process parameters conditions, the calculated result agrees with the experimental result, this indicates that the established numeric model is correct and reliable.(3) Lastly, using the numerical simulation method, the pool profile, the shape of heat affected zone have been forecasted, then the forming mechanism of microstructure and the influence of coating thickness,density and laser remelting process parameters for temperature field are discussed. The relationship between the corrosion resistance, tensile test result and microstructure is analysed in order to obtain laser remelting process parameters which make temperature field of laser remelting be reasonable.更多还原