【作者】 王沐；

【导师】 米高阳；

【作者基本信息】 华中科技大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 随着时代的发展,现代工业不断进步,核电、航天等领域对优质板材和中厚板结构的需求增加,以及对焊接质量的要求提高,激光焊接的问世,因为它具有能量密度高、生产率高、易于自动化、焊接精度高、定向性好等技术优势,被认为在中厚板焊接中具有明显优势。但中厚板的铝合金激光焊接也存在成形性低、气孔率高、抗拉强度低等问题。为了解决这些问题,本文考虑了利用磁场的激光扫描技术对焊接质量的影响,采用了纵向、横向和圆形三种扫描方式。本文研究了10mm厚6061T6铝合金对接焊缝,发现激光扫描可以抑制缺口和飞溅,纵向扫掠效果最小,环扫效果最大,通过增加磁场可以抑制焊缝缺口、滑坡和驼峰,场强越大,焊缝表面的下塌越小,背部更加平整,大大改善焊缝的形成。用高速摄像机观察焊接过程,发现单个激光熔池振荡更剧烈,激光纵向扫描焊接和激光横向扫描焊接,由于激光扫描路径有陡峭的拐点,熔池的振荡也更锐利,圆形激光扫描轨迹更平滑,熔池也比较平滑。引入磁场后,在洛伦兹力的影响下,熔池的运动减慢,熔池的波动减小,焊接过程在磁场的作用下趋于稳定。使用X射线探伤表明,在200m T的磁场中进行激光圆形扫描时焊缝的最小气孔率为1.218%。磁场可以提高焊缝的抗拉强度,激光焊缝强度的纵向扫描几乎没有增加,横向和圆形扫描可以更明显地提高焊缝的抗拉强度,圆形扫描的效果是最佳,200m T下激光圆形扫描焊缝的抗拉强度为318.85MPa,达到母材的83.91%。激光扫描可以抑制焊缝软化,提高焊接接头的硬度。更多还原

【Abstract】 With the development of the times and the continuous progress of modern industry,the demand for high-performance thick plate and medium thick plate structures and welding quality in the fields of nuclear power and aerospace are becoming higher and higher.After the emergence of laser welding,due to its technical advantages such as high energy density,high production efficiency,easy automation,high welding precision and good directionality,It is considered to have obvious advantages in medium and heavy plate welding.In order to solve these problems,this paper studies the influence of magnetic field assisted laser scanning welding technology on welding quality,and adopts three scanning trajectories:longitudinal scanning,transverse scanning and circular scanning.The main research conclusions are as follows.In this paper,the butt penetration weld of 10 mm thick 6061T6 aluminum alloy is studied.It is found that laser scanning can inhibit the pit and splash defects,the longitudinal scanning effect is the smallest,and the circular scanning effect is the largest.By increasing the magnetic field,the pit,stay and hump of the weld can be restrained.The larger the magnetic field strength,the smaller the stay on the weld surface,the smoother the back,and significantly improve the weld formation.The welding process is observed by high-speed camera.The results show that the oscillation of molten pool in single laser welding is more intense.Due to the sharp inflection point of laser scanning track,the fluctuation of molten pool is also more intense in laser longitudinal scanning welding and laser transverse scanning welding.The excitation scanning track of laser circular scanning welding is smoother and the molten pool is relatively more stable.After applying the magnetic field,the flow of the molten pool is restrained,the oscillation of the molten pool is reduced,and the welding process becomes stable under the action of the magnetic field.The results of X-ray flaw detection show that the porosity of laser circular scanning welding is the lowest,up to 1.218%.The magnetic field can improve the tensile strength of the weld.The longitudinal laser scanning can hardly improve the tensile strength of the weld.The transverse scanning and circular scanning can significantly improve the tensile strength of the weld.The circular scanning has the best effect.The tensile strength of the laser circular scanning welded weld at 200 MT is 318.85 mpa,which reaches 83.91% of the base metal.Moreover,laser scanning can inhibit the joint softening of weld and improve the hardness of welded joint.更多还原