CAJ | 학술논문

采用Nd：YAG脉冲激光器实现了200μm厚热轧态NiTiNb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27 Hz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。
채용Nd：YAG맥충격광기실현료200μm후열알태NiTiNb형상기억합금적격광한접，연구격광평균공솔、격광맥관화격광빈솔등주요공예삼수대한접접두형모적영향，분석료한봉열영향구현미조직、역학성능적변화규률。결과표명：격광평균공솔、격광맥관화격광빈솔수요량호필배재능획득교호성능적한접접두。당격광평균공솔위16.8 W、격광맥관위4.5 ms、격광빈솔위4.5 Hz시，한봉적항랍강도최고，체도모재적95%。수착격광평균공솔、격광맥관적증가，한봉열영향구적관도선증가후감소。격광빈솔증가후，열영향구정립변조。당빈솔위27 Hz시，재고근열영향구적한봉출현료일개조대수지정구역。모재단구적인와대이심，위전형적인성단렬。한봉단구적인와소이천，정어란형。열영향구적현미경도고우모재적，저우한봉중심구역적。
Nd:YAG laser was used to weld hot-rolled-state NiTiNb shape memory alloy with thickness of 200 μm. The effects of main process parameters including average power of laser, pulse width of laser and frequency of laser to the morphology of the welding joint were studied, then the transformation law about the microstructure of heat-affected zone and mechanical properties of the welding joint were analyzed. The results indicate that a perfect welding joint needs a good match of average power, pulse width and frequency of laser. The highest tensile strength of welding joint reaches 95% of that of the base material obtained when average power of laser is 16.8 W, pulse width of laser is 4.5 ms and frequency of laser is 4.5 Hz. With increasing the average power and pulse width of laser, the width of heat-affected zone first increases, then decreases. The grains in the heat-affected zone continue to coarsen with increasing the frequency of laser. A gross dendrites area arises in the welding joint near the heat-affected zone when the frequency of laser is 27 Hz. The dimples in the parent material fracture is large and deep, which is classic ductile fracture. The dimples in the welding joint fracture are small and shallow, which look like roes. The micro-hardness of heat-affected zone is higher than that of the base material but lower than that of the centre area of welding joint.