高硅铝合金搅拌摩擦焊及激光焊的工艺研究

发布时间：2018-01-20 13:44

本文关键词： 高硅铝合金搅拌摩擦焊脉冲激光焊　出处：《合肥工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：高硅铝合金因其密度低、线膨胀系数低、比强度高等特点,而广泛应用于电子封装领域。但是高硅铝合金内硅颗粒含量较多,因此其熔焊性能较差,具有较高的裂纹倾向。本文采用脉冲激光焊机针对Al-27Si进行了表面脉冲激光熔敷焊接试验,通过调整电流、焊速、脉宽和频率,系统分析各参数对焊缝成形质量及形状尺寸的影响规律。结果表明：提高电流、脉宽和频率,均能增加热输入,增大熔深；增大焊速,焊缝熔深减小,鱼鳞状波纹宽度增大。综合分析,在电流90A,脉宽2ms,频率30Hz,焊速200mm/min焊接规范下,能得到成形质量很好的焊缝。然后,采用搅拌摩擦焊接方法分别对Al-27Si、Al-50Si进行焊接试验。研究表明,Al-27Si、Al-50Si合金FSW接头可分为母材区、焊核区、轴肩影响区和热机影响区四个区域。母材组织为a-Al基体和较大硅颗粒；焊核区组织为少量a-Al基体和弥散分布的细小硅颗粒；轴肩影响区内硅比焊核区细小；热机影响区是焊核区与母材的过渡区域,该区域硅颗粒也得到细化。旋转速度的增加,将导致“洋葱环”形状明显,细小硅的数量增多,显微硬度增大。当转速达到1200r/min时,焊核区显微硬度平均值达220HVo.2,比母材高100HVo.2。分析认为Si颗粒的细化作用是显微硬度上升的主要原因。随焊速降低,各区域内硅的尺寸减小。在转速为1200r/min、焊速为50mm/min、下压量为0.2mmm的焊接规范下,Al-27Si合金的同种焊接和Al-50Si合金的同种焊接均能实现良好的连接。Al-27Si与Al-50Si的异种搅拌摩擦焊接中,Al-27Si合金位于前进侧时的异种搅拌摩擦焊接,焊后表面成形较好,毛刺飞边较少。降低焊速,可有效改善焊核区及轴肩影响区组织不均匀现象。Al-50Si合金位于前进侧时的异种搅拌摩擦焊接,焊后表面成形较差。降低焊速,不能改善焊核区及轴肩影响区组织不均匀现象。
[Abstract]:High silicon aluminum alloy is widely used in electronic packaging field because of its low density, low linear expansion coefficient and high specific strength. In this paper, a pulsed laser welding machine is used to test the surface pulsed laser cladding welding for Al-27Si. The welding current, welding speed, pulse width and frequency are adjusted by adjusting the current, welding speed, pulse width and frequency. The effects of various parameters on weld quality and shape and size are systematically analyzed. The results show that increasing current, pulse width and frequency can increase heat input and increase penetration depth. With the increase of welding speed, the weld penetration depth decreases and the width of fish squama ripple increases. The comprehensive analysis shows that under the welding specifications of 90A, 2ms, 30Hz, 200mm / min, the welding speed is 200 mm / min. The weld seam with good forming quality can be obtained. Then, the welding test of Al-27Si-Al-50Si is carried out by friction stir welding method. The results show that Al-27Si is welded by friction stir welding. The Al-50Si alloy FSW joint can be divided into four regions: the base metal zone, the nuke zone, the shaft-shoulder zone and the thermo-mechanical zone. The base metal structure is a-Al matrix and larger silicon particles. The microstructure of the nugget zone is a small amount of a-Al matrix and dispersed fine silicon particles. The size of silicon is smaller than that of nugget in the influence zone of shaft shoulder. The influence zone of heat engine is the transition zone between the nuke zone and the base metal, and the silicon particles in this area are also refined. The increase of rotation speed will lead to the obvious shape of "onion ring" and the increase of the amount of fine silicon. The average value of microhardness in the nugget zone is 220 HVo.2 when the rotational speed reaches 1 200 r / min. The results show that the refinement of Si particles is the main reason for the increase of microhardness. With the decrease of welding speed, the size of silicon in each region decreases, and the rotation speed is 1 200 r / min. The welding speed is 50 mm / min and the pressure is 0.2 mm. The same welding of Al-27Si alloy and the same welding of Al-50Si alloy can achieve good connection. Al-27Si and Al-50Si in dissimilar friction stir welding. When the Al-27Si alloy is located on the forward side, the surface is formed better and the burr flange is less, and the welding speed is decreased. The dissimilar friction stir welding of Al-50Si alloy located on the forward side can be effectively improved, the surface forming after welding is poor, and the welding speed is decreased. It can not improve the uneven structure of the nugget zone and the zone affected by the shaft shoulder.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.14

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