激光焊接TA2板材气孔及耐蚀性能
毕业论文关键词：激光焊；TA2工业纯钛；气孔；耐蚀性能
Abstract In this paper, the laser power, welding current and welding speed and other parameters are changed in order. By means of metallographic, SEM and calculation of porosity, the effect of different welding parameters on the weld porosity was studied. At the same time, this paper uses hydrofluoric acid to corrode, corrosion resistance of weld test and analysis of the TA2 pure titanium laser welding. The results show that when the welding speed is constant, with the increase of the laser power, the average porosity of the weld increases first and then decreases. When the laser power is constant, with the increase of the welding speed, the average porosity of the weld increases first and then decreases obviously. The average porosity of TA2 weld is determined by the degree of diffusion of hydrogen and the existence time of molten pool liquid. When the two control mechanisms are weak, the average porosity of the weld can reach the maximum value. And, due to the appearance of pores, the corrosion resistance will be reduced. In terms of corrosion resistance, the corrosion resistance of TA2 pure titanium substrate is better than that of TA2 titanium laser welded joint. In the acidic seawater environment, the corrosion resistance of the weld is decreased with the increase of the acidity. In the microstructure of welded joint, the coarse columnar alpha grains are better than the corrosion resistant properties of needle like alpha grains, serrated alpha grains and a small amount of twins.
Keywords: laser welding; TA2 industrial pure titanium; porosity; corrosion resistance
目录
第一章绪论.1
1.1激光焊接的发展与现状.1
1.2钛的性能特点及应用..2
1.3钛的耐蚀性能..5
1.3.1钛在酸性材料中的耐蚀性能.5
1.3.2钛的几种局部腐蚀特性6
1.4激光焊钛合金的主要缺陷7
1.5主要研究内容..8
第二章实验材料及方法10
2.1实验材料..10
2.2实验设备..10
2.3实验方法..12
2.3.1激光焊接实验气孔研究.12
2.3.2腐蚀实验.12
第三章实验结果与分析15
3.1激光焊接实验气孔分析..15
3.1.1焊缝气孔分布与形貌特征分析.15
3.1.2激光功率对气孔的影响.17
3.1.3焊接速度对气孔的影响.18
3.1.4气孔形成影响机理19
3.2腐蚀实验分析20
3.2.1失重法测腐蚀速率20
3.2.2焊缝及母材腐蚀形貌SEM分析..21
3.2.3腐蚀焊缝金相分析23
结论.26