【作者】 张海荣；

【导师】 张屹； 陈祖海；

【作者基本信息】 湖南大学 ， 机械工程， 2011， 硕士

【摘要】 随着人们对钢铁防腐要求的提高,镀锌钢板作为一种经济实惠耐用及抗腐蚀性强的材料越来越受到广泛地应用。激光焊接技术在汽车零部件中有着极其重要的作用。激光焊接速度快,热影响区小,焊缝组织细化,焊接变形小,一般激光焊缝的机械性能都强于母材。本文研究了镀锌钢激光焊接的等离子体温度与工艺参数的关系,并且在此基础上重点研究了添加不同浓度铜粉的镀锌钢光纤激光搭接焊实验。首先,采用基于密度泛函理论Castep程序软件,计算了锌金属间化合物CuZn、MgZn2与NiZn的结构稳定性、弹性常数等力学性质。计算了不同浓度的Cu与Zn结合形成的固溶体的力学性能。通过对锌合金化合物的模拟,为后文进行镀锌钢的激光添粉焊接作一定的理论指导与预测。其次,通过研究镀锌钢激光焊接的等离子体温度与工艺参数,分析得到了激光功率、焊接速度、离焦量、保护气体流量与等离子体温度的关系曲线,研究结果表明,工艺参数对等离子体温度有一定影响,并且保护气体流量对等离子体温度影响比较明显,随保护气体流量增大而减少;焊接速度对等离子体温度影响最小,上下偏差为1323K,并且等离子体温度的变化可以为激光深熔焊接的实时监测及预测提供一定的理论指导。最后,重点进行了添加不同浓度的铜粉的镀锌钢光纤搭接焊实验,检测了焊接接头的力学性能、断口形貌、成分分布、主要物相。通过试验数据的处理和分析,得出了添加不同浓度铜粉的镀锌钢光纤搭接焊的焊接接头性能。更多还原

【Abstract】 Zinc-coated steel is an important commercial material.It is durable, cheap and very useful for combating corrosion. Laser welding technology plays an important role in automobile parts. Laser welding speed is fast, heat affected zone is small, weld microstructure is refining, laser welding deformation is small, generally speaking, mechanical properties of weld seam is stronger than the base metal. In this paper, the relationship between plasma temperature and technological parameter on laser welding of galvanized steel is mainly studied. In addition, experiments of laser lap welding of galvanized steels with the different concentrations of Cu powder are mainly researched. Research contents of the topic are as follows.Firstly, structural stability and elastic properties of CuZn、MgZn2 and NiZn have been determinied from first-principles calculation by using Castep program based on the density functional theory. Mechanical property of solid solutions, that is formed by the combination of different concentrations of Cu and Zn has been studied. Through the simulation of zinc alloy and its compounds, the laser welding of galvanized steel with the Cu powder provides an certain theoretical guidance and prediction.Secondly, through the research of the relationship between plasma temperature and technological parameter on laser welding of galvanized steel, relation curves of laser power, speed of welding, defocused distance, shielding gas flow and plasma temperature are analyzed. It has been shown that technological parameter has a certain effect on plasma temperature. Shielding gas flow has obvious impact on the plasma temperature. It decreases with the increasing of shielding gas flow. However, the influence of speed of welding on plasma temperature is least, whose deviation is 1323K. Changes of plasma temperature can provide certain theoretical guidance for moniting and predicting of laser welding with deep penetration.Finally, the experiments of laser lap welding of galvanized steels with the different concentrations of Cu powder are mainly carried out. The mechanical properties, fracture morphology, component distribution and the main phase of the welded joint are detected. Through processing and analysis of experiment data, the property of welding joint of laser lap welding of galvanized steels with the Cu powder of different concentrations is concluded.更多还原