对2219-T6铝合金进行搅拌摩擦焊接(FSW),并采用三点弯曲试验方法评价接头的弯曲性能和用扫描电镜观察接头的弯曲断口形貌。结果表明:正弯时拉应力作用于FSW焊缝上表面,压应力作用于下表面,表现出较好的塑性变形;背弯时受力相反,下表面...对2219-T6铝合金进行搅拌摩擦焊接(FSW),并采用三点弯曲试验方法评价接头的弯曲性能和用扫描电镜观察接头的弯曲断口形貌。结果表明:正弯时拉应力作用于FSW焊缝上表面,压应力作用于下表面,表现出较好的塑性变形;背弯时受力相反,下表面中心线出现裂纹并沿焊核区与热机影响区之间的过渡区扩展。无缺陷FSW接头的最大弯曲力Fbb和抗弯强度σbb最大值分别为3.6 k N、503 MPa,以韧性断裂方式为主;而有缺陷FSW接头的Fbb和σbb分别仅为2.5 k N、395 MPa,以准解理断裂方式为主。展开更多
铝合金热加工过程的冶金行为比较复杂,在电阻点焊快速加热和冷却条件下,极易产生裂纹缺陷。基于虚拟仪器技术,以Lab VIEW为软件平台,结合Matlab数值分析软件,构建了电阻点焊过程声发射信号采集分析及铝合金点焊裂纹监测系统。以2A12铝...铝合金热加工过程的冶金行为比较复杂,在电阻点焊快速加热和冷却条件下,极易产生裂纹缺陷。基于虚拟仪器技术,以Lab VIEW为软件平台,结合Matlab数值分析软件,构建了电阻点焊过程声发射信号采集分析及铝合金点焊裂纹监测系统。以2A12铝合金电阻点焊熔核冷却结晶过程,即点焊焊接循环维持阶段的声发射信号为研究对象,提取与声发射信号强度相关的振铃计数、能量、有效电压及5层小波分解125～250 k Hz频带能量系数4个特征参数作为输入矢量,裂纹作为输出矢量,建立3层BP神经网络铝合金点焊裂纹的监测模型,并利用测试样本对该模型进行验证。结果表明,裂纹监测的正确率达到89.1%,为监测铝合金电阻点焊裂纹提供了一种有效的方法。展开更多
An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior du...An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior during Mg-Ti friction welding process. The results show that the friction coefficient mainly experiences two steady stages. The first steady stage corresponds to the Coulomb friction with material abrasion. The second steady stage corresponds to the stick friction with fully plastic flow. Moreover, the increasing rates of axial displacement, temperature and friction coefficient are obviously enhanced with the increase of rotation speed and axial pressure. It can also be found that the there exists rapid diffusion phenomenon in the Mg-Ti friction welding system. The large deformation activated diffusion coefficient is about 105 higher than that activated by thermal.展开更多
文摘对2219-T6铝合金进行搅拌摩擦焊接(FSW),并采用三点弯曲试验方法评价接头的弯曲性能和用扫描电镜观察接头的弯曲断口形貌。结果表明:正弯时拉应力作用于FSW焊缝上表面,压应力作用于下表面,表现出较好的塑性变形;背弯时受力相反,下表面中心线出现裂纹并沿焊核区与热机影响区之间的过渡区扩展。无缺陷FSW接头的最大弯曲力Fbb和抗弯强度σbb最大值分别为3.6 k N、503 MPa,以韧性断裂方式为主;而有缺陷FSW接头的Fbb和σbb分别仅为2.5 k N、395 MPa,以准解理断裂方式为主。
文摘铝合金热加工过程的冶金行为比较复杂,在电阻点焊快速加热和冷却条件下,极易产生裂纹缺陷。基于虚拟仪器技术,以Lab VIEW为软件平台,结合Matlab数值分析软件,构建了电阻点焊过程声发射信号采集分析及铝合金点焊裂纹监测系统。以2A12铝合金电阻点焊熔核冷却结晶过程,即点焊焊接循环维持阶段的声发射信号为研究对象,提取与声发射信号强度相关的振铃计数、能量、有效电压及5层小波分解125～250 k Hz频带能量系数4个特征参数作为输入矢量,裂纹作为输出矢量,建立3层BP神经网络铝合金点焊裂纹的监测模型,并利用测试样本对该模型进行验证。结果表明,裂纹监测的正确率达到89.1%,为监测铝合金电阻点焊裂纹提供了一种有效的方法。
基金Projects (51101126, 51071123) supported by the National Natural Science Foundation of ChinaProjects (20110491684, 2012T50817) supported by the China Postdoctoral Science FoundationProject (20110942K) supported by the Open Fund of State Key Laboratory of Powder Metallurgy of Central South University, China
文摘An innovative physical simulation apparatus, including high speed camera, red thermal imaging system, and mechanical quantity sensor, was used to investigate the friction heat generation and atom diffusion behavior during Mg-Ti friction welding process. The results show that the friction coefficient mainly experiences two steady stages. The first steady stage corresponds to the Coulomb friction with material abrasion. The second steady stage corresponds to the stick friction with fully plastic flow. Moreover, the increasing rates of axial displacement, temperature and friction coefficient are obviously enhanced with the increase of rotation speed and axial pressure. It can also be found that the there exists rapid diffusion phenomenon in the Mg-Ti friction welding system. The large deformation activated diffusion coefficient is about 105 higher than that activated by thermal.
