Hot Cracking in AZ31 and AZ61 Magnesium Alloy

This paper examined the impact of the number of thermal cycles and augmented strain on hot cracking in AZ31 and AZ61 magnesium alloy. Statistical analyses were performed. Following observation using a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS) was used for component analysis. Results showed that Al content in magnesium alloy has an effect on hot cracking susceptibility. In addition, the nonequilibrium solidification process produced segregation in Al content, causing higher liquid Mg-alloy rich Al content at grain boundaries, and resulting into liquefied grain boundaries of partially melted zone (PMZ). In summary, under multiple thermal cycles AZ61 produced serious liquation cracking. AZ61 has higher (6 wt%) Al content and produced much liquefied Mg17Al12 at grain boundaries under multiple thermal cycles. The liquefied Mg17Al12 were pulled apart and hot cracks formed at weld metal HAZ due to the augmented strain. Since AZ31 had half the Al content of AZ61, its hot-cracking susceptibility was lower than AZ61. In addition, AZ61 showed longer total crack length (TCL) in one thermal cycle compared to that in three thermal cycles. This phenomenon was possibly due to high-temperature gasification of Al during the welding process, which resulted in lower overall Al content. Consequently, shorter hot cracks exhibited in three thermal cycles. It was found the Al content of AZ31 and AZ61 can be used to assess the hot-cracking susceptibility.     

可夹持焊枪的氩弧焊自动焊接装置

针对人工焊接时由于焊接接头的熔深不同、焊缝宽度不同以及焊缝各处差异等人为因素所导致的焊接缺陷,设计了一种可夹持焊枪的氩弧焊自动焊接装置。介绍了可夹持焊枪的氩弧焊自动焊接装置的机械结构、控制模块及功能。该装置保证了稳定的焊接速度和焊接高度,实现了焊枪的三维移动和焊接过程的自动化,提高了焊接效率和焊接质量。利用此装置进行氩弧熔覆耐磨复合涂层的验证试验,试验结果表明该装置可实现组织均匀且与基底实现冶金结合的复合涂层,熔覆层硬度是基体Q235钢的6.4倍,耐磨性和表面质量良好。     

Neural network modeling for dynamic pulsed GTAW process with wire filler based on MATLAB

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GTAW用送丝装置研制

开发了一套ＧＴＡＷ焊机器人配套用送丝装置。在ＣＯ２焊送丝机基础上增加了一级减速器,调速电路采用自行设计的测速负反馈控制系统。送丝速度调节范围达到５０－３５００ｍｍ／ｍｉｎ,网压波动和送阻力变化时,送丝速度变化率在１．５％以内,完全满足自动ＧＴＡＷ焊的需要。     

Monitoring of weld joint penetration by sensing double-side vision images of weld pool

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几种施焊手法对管道钨极氩弧焊焊接质量的影响

钨极氩弧焊(GTAW)具有操作方便,焊接质量好等优点,在关键的焊接生产中应用较多,特别是在压力管道以及锅炉压力容器的打底焊中被普遍采用。在氩弧焊焊接过程中,焊工采用不同的焊接手法对焊接质量有较大的影响。以小口径管道氩弧焊为例,分析了三种施焊手法对焊道外观成型及焊接质量的影响,总结出管道现场焊接中合适的焊接手法,以提高压力管道现场焊接的一次合格率。     

基于视觉的焊缝跟踪模糊控制系统的研制

本文论述一种明型焊缝跟踪控制用视觉传感器ＣＣＤ检测焊缝跟踪偏差，并通过一个参数有调整模糊控制器实现偏差的调节。实验证明，与传统控制方法相比，该系统能够有效地提高焊缝跟踪精度。     

Understanding the changing mechanism of arc characteristics in ultrasound-magnetic field coaxial hybrid gas tungsten arc welding

Ultrasound-magnetic field coaxial hybrid Gas Tungsten Arc Welding (U-M-GTAW) is proposed as a means to control arc characteristics. The arc characteristics and the mechanism to change them, in an ultrasound-magnetic field coaxial hybrid GTAW, were studied by both experimental and theoretical analyses. The results showed that a periodic rotation and compression of the arc shape were obtained in U-M-GTAW and the arc energy was also enhanced. The most obvious compression of the arc shape in U-M-GTAW was obtained, compared with GTAW, M-GTAW and U-GTAW. At the same time, a periodic rotation of the arc was observed in U-M-GTAW. The geometric parameters of the arc shape in U-M-GTAW are reduced more than double compared with traditional GTAW. The arc voltage in the hybrid GTAW was increased, especially in the U-M-GTAW. The electromagnetic force and acoustic radiation force were the main factors for the change of arc characteristics in the U-M-GTAW.