超薄NiTiNb记忆合金激光焊焊缝成形及热影响区的组织和性能

发布时间：2018-04-28 22:04

本文选题：NiTiNb形状记忆合金 + 激光技术　；参考：《中国有色金属学报》2015年01期

【摘要】：采用Nd:YAG脉冲激光器实现了200μm厚热轧态Ni Ti Nb形状记忆合金的激光焊接,研究激光平均功率、激光脉宽和激光频率等主要工艺参数对焊接接头形貌的影响,分析了焊缝热影响区显微组织、力学性能的变化规律。结果表明:激光平均功率、激光脉宽和激光频率需要良好匹配才能获得较好性能的焊接接头。当激光平均功率为16.8 W、激光脉宽为4.5 ms、激光频率为4.5 Hz时,焊缝的抗拉强度最高,达到母材的95%。随着激光平均功率、激光脉宽的增加,焊缝热影响区的宽度先增加后减小。激光频率增加后,热影响区晶粒变粗。当频率为27Hz时,在靠近热影响区的焊缝出现了一个粗大树枝晶区域。母材断口的韧窝大而深,为典型的韧性断裂。焊缝断口的韧窝小而浅,呈鱼卵形。热影响区的显微硬度高于母材的,低于焊缝中心区域的。
[Abstract]:Laser welding of 200 渭 m thick hot rolled Ni-TiNb shape memory alloy was realized by using Nd:YAG pulse laser. The effects of laser average power, laser pulse width and laser frequency on the morphology of welded joints were studied. The changes of microstructure and mechanical properties of HAZ were analyzed. The results show that the laser average power, laser pulse width and laser frequency need to be well matched in order to obtain a better performance welded joint. When the average laser power is 16.8 W, the laser pulse width is 4.5 Ms and the laser frequency is 4.5 Hz, the tensile strength of the weld is the highest, reaching 95% of the base metal. With the increase of laser average power and laser pulse width, the width of HAZ increases first and then decreases. With the increase of laser frequency, the grain size in the heat affected zone becomes coarser. When the frequency is 27Hz, a coarse dendritic region appears in the weld near the heat affected zone. The dimple of base metal fracture is large and deep, which is a typical ductile fracture. The dimple of weld fracture is small and shallow, and it is like a fish egg. The microhardness of the HAZ is higher than that of the base metal and lower than that of the central weld.
【作者单位】：南昌航空大学航空制造工程学院;哈尔滨工业大学先进焊接与连接国家重点实验室;上海航天设备制造总厂;
【基金】：上海航天科技创新基金资助项目(SAST201209) 江西省科技支撑计划项目(20133BBE50021) 江西省高等学校科技落地计划项目(KJLD14055)
【分类号】：TG456.7

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