复杂环境下氧化铝储槽定向爆破拆除

在较为复杂的环境下,爆破拆除钢筋混凝土氧化铝储槽。该储槽自重大、呈圆形,内有4根立柱支撑下料漏斗。为使储槽顺利定向倒塌,通过爆破方案选择、参数确定,采取梯形切口和预处理以及安全防护和减振措施,使储槽爆破拆除获圆满成功。     

基于数值模拟的挤压参数对AZ91镁合金管转角焊合室分流挤压焊合压力的影响规律研究

提出了一种镁合金管材转角焊合室分流挤压新工艺，该工艺可在有效延长焊合室长度和焊合时间前提下保证舌针刚度，从而保证管材尺寸精度，并且可通过转角剪切变形机制增加预焊合金属变形量和动态再结晶程度，从而有利于提高管材性能和焊缝焊合性能。利用有限元法揭示了转角焊合室分流挤压成形过程中金属的流动特征，应变分布特征和焊合室内的静水压力分布特征。结果表明，整个挤压过程无金属折叠，从而保证管材的表面质量；流经转角后预焊合金属变形量明显增加，有利于提高管材质量和焊缝质量。最后，研究揭示了坯料初始温度，挤压速度和模具转角对焊合室内静水压力的影响规律。结果表明，随着挤压速度的增加和模具转角的增大，转角焊合室内静水压力增大；随着坯料预热温度的增加，转角焊合室内静水压力呈先增大后减小的趋势。     

非径向管板焊接接头的超声检测

对AP1000压水堆核电站安全壳贯穿件的非径向管板焊接接头结构特点进行了介绍,并分析其超声检测工艺的重点和难点。通过建立统一的缺陷定位坐标系并结合被检构件的几何特点进行综合分析,推导得出了h值(缺陷回波最高点距套管外壁的距离)的计算方法。为超声检测对这类焊接接头缺陷的准确识别和定位提供了行之有效的方法,为解决这类焊接接头的超声检测技术受限区提供了行之有效的措施。     

An integrated model for analysing the effects of ultrasonic vibration on tool torque and thermal processes in friction stir welding

An integrated model of ultrasonic vibration enhanced friction stir welding (UVeFSW) is developed by integrating the thermal-fluid model with the ultrasonic field model and tool torque model. The tool torque and the heat generation rate at tool/workpiece contact interfaces are coupled with the interfacial temperature, strain rate and ultrasonic energy density. The model is used in quantitatively analysing the effects of ultrasonic vibration on tool torque and thermal processes in friction stir welding (FSW). The results show that ultrasonic vibration reduces the flow stress, which results in a decreasing of tool torque, interfacial heat generation rate and interfacial temperature. The complicated interaction of ultrasonic energy with the thermal processes in FSW leads to a gentle thermal gradient and an enhanced plastic material flow in UVeFSW. The model is validated by a comparison of the calculated thermal cycles and tool torque at various welding parameters with the experimentally measured ones.     

Measurement of residual stresses in dissimilar friction stir-welded aluminium and copper plates using the contour method

The longitudinal residual stresses in the friction stir-welded plates of 5A06 aluminium and pure copper were determined using the contour method. The results revealed the presence of high tensile and compressive residual stresses on the aluminium and copper sides, respectively. The residual stresses were detected on the weld zone as well as the thermo-mechanically affected zone (TMAZ) of the aluminium plate. In contrast, the compressive residual stresses in the copper plate had a much narrower width along the weld line. Peak tensile stresses up to 240?MPa were found in the TMAZ of the aluminium plate.     

Effect of metallurgical evolution during post-weld aging treatment on localised corrosion of resistance spot welding joints of A286 superalloy

The combined effect of resistance spot welding and precipitation hardening on the localised corrosion of A286 superalloy is studied. The specimens tested by double loop electrochemical potentiokinetic reactivation were welded in the solution treated condition, and then subjected to different precipitation hardening treatments. For both base metal and weld nugget, the maximum localised corrosion is reached when η phase is clearly observable. The fact that the localised corrosion resistance of weld nugget is different from that shown by base metal may be explained by the segregation of Ni and Ti towards the interdendritic region of weld nugget (studied by using scanning electron microscope/energy dispersive X-ray analysis).     

不锈钢管气体保护焊接工艺研究

为了确保不锈钢管道的焊接质量，通过分析不锈钢焊接及焊接保护气体的特点，对焊接工艺进行了设计，并对某项目规格为Φ323.9 mm×25.4 mm奥氏体不锈钢管道背面充氩焊接工艺进行了分析介绍。结果表明，采用可靠的充气工装使焊缝背面得到有效的保护（残余氧含量按不超过1%的水平），防止焊缝背部出现氧化现象；选取合理的气体流量和压力，能确保焊缝内部成形，满足焊缝质量要求；采用合适的焊接工艺与背面保护措施，可获得满足要求的焊接接头性能。     

某X65钢级输气管道环焊缝泄漏失效分析

针对某X65输气管道环焊缝泄漏失效问题，通过无损探伤、硬度试验、金相组织分析、扫描电镜分析等方法，对钢管环焊缝进行了分析研究。分析结果显示，焊接接头组织未见明显异常，但裂纹附近存在疏松组织，该疏松组织主要元素为铁和氧，以及少量铝、硅、钙、硫元素。研究表明，该疏松组织为焊接时未清理干净的焊渣，在外力和内压作用下，夹渣处裂纹相互贯穿形成穿透性裂纹，裂纹由内表面向外表面扩展，导致焊缝产生开裂而发生泄漏。     

全自动焊含缺陷环焊缝管段承载能力研究

为了研究全自动焊在役管线的真实承压能力，通过水压爆破试验对全自动焊含缺陷环焊缝在役管段的承载能力进行研究。研究结果表明，全自动焊焊接工艺下环焊缝缺陷主要是未熔合缺陷，且3种含未熔合缺陷管段起爆点、爆破压力、撕裂方向大致相同；含3种未熔合缺陷环焊缝管段的真实爆破压力均大于爆破压力的理论计算值，远远满足现场运行所需要的承载能力；含缺陷环焊缝的存在并没有对在役管段的整体承载能力造成影响；管段的承载能力主要取决于母材自身的材料性能。     

直缝埋弧焊钢管焊缝点状缺陷原因分析及改进

为了解决壁厚23 mm直缝埋弧焊管出现的焊缝点状缺陷问题，通过超声波探伤和宏观金相检测对实际生产过程中出现的焊缝点状缺陷不合格试样进行了分析，对铣边坡口形状、焊接工艺参数、焊接材料、焊接设备及焊件清理等方面给出了相应的优化改进措施。现场应用效果表明:这些措施的实施有效控制了此类直缝埋弧焊管焊缝中的点状缺陷，保证了直缝埋弧焊管焊缝形貌及各项力学性能指标，提高了焊接质量。