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From the viewpoint of welding mechanics, two new welding methods-welding with trailing peening and welding with trailing impactive rolling were introduced. For aluminum alloy thin-shell structures with high strength, welding will lead to hot cracking, poor joint and distortion. In order to solve them, trailing impactive device was used behind welding torch to impact the different positions of welded joints, thus realizing the welding with free-hot cracking, low distortion and join tstrengthening. By use of impactive rolling wheels instead of peening heads, the outlook of welded specimen can be improved and stress concentration at weld toes can be reduced. Equipment of this technology is simple and portable. It can used to weld sheets, longitudinal and ring-like beams of tube-like structures, as well as the thin-shell structures with closed welds such as flanges and hatches. So the technology has the wide application foreground in the fields of aviation and aerospace. 相似文献
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X.S.Liu H.Y.Fang W.L.Xu Z.B.Dong D.Y.Yu 《金属学报(英文版)》2004,17(3):311-316
It is a promising and new technology to apply welding with trailing peening to control welding stress and distortion of titanium alloy. Numerical simulation of conventional welding and welding with trailing peening of the titanium alloy sheet is carried out, using nonlinear finite element theory and the engineering analysis software MARC. The result shows that welding with trailing peening technology reduces longitudinal residual stress in welding joint effectively, and it is more effective to reduce residual stress to peen the weld than to peen the weld toe. It is a effective result that other technolooy and method used in welding can never achieved. 相似文献
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采用云纹分析的试验力学方法,研究了不同情况下LYl2CZ高强铝合金焊接接头应变场的分布特点。研究结果表明,断裂前夕,常规焊接头的云纹条纹稀疏且不均匀,拉伸过程中应力集中在薄弱环节焊趾部位,焊接接头的力学性能指标较差;采用随焊锤击工艺,由于在焊接过程中同步锤击强化了焊趾部位,断裂前夕焊接接头的云纹条纹分布比较密集均匀,断裂部位由焊趾转移到焊缝,焊接接头的力学性能指标较常规焊有了较大提高,这充分说明随焊锤击技术对于实现高强铝合金焊接接头的强化是行之有效的。 相似文献
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In order to control welding stress and distortion, a new welding with trailing peening method based on the electromagnetic hammer was developed. This method uses the idea of constant frequency pulse width modulation for designing the control circuit of peening force and peening frequency. The peening force can be adjusted between 0 and 1 000 N and the peening frequency ranges from 0 to 25 Hz. Peening force is applied to the weld metal and the weld toe during the welding by peening head. The experiments show that the method is portable and flexible, and it can adjust the distribution state of welding residual stress, making grain refinement. When the peening force is changed to 700 N and the peening frequency to 3 Hz, both the transverse and longitudinal residual stresses will drop obviously. 相似文献
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随焊激冷减小铝合金薄板的焊接变形 总被引:8,自引:0,他引:8
研究了随焊激冷减小铝合金薄板焊接变形的效果及夹具的散热条件对该效果的影响,研究表明,随焊激冷能够减小铝合金薄板的焊接变形,其效果受夹具自身冷却作用影响很大。随着夹具散热条件的降低,随焊激冷所起的作用增强,但降低焊接变表的效果仍不够明显,适当预热夹具本身可以减小焊接变形,但更重要的是预热使激冷造成了温差拉伸,因此获得了最小的焊接变形。 相似文献
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Christian Hagenlocher Daniel Weller Rudolf Weber Thomas Graf 《Science & Technology of Welding & Joining》2013,18(4):313-319
ABSTRACTThe grain structure of laser welded AlMgSi-alloys was varied by adapting the welding parameters and alloying additives. The hot cracking susceptibility was determined by the critical strain rate, measured by the application of digital image correlation in a self-restrained hot cracking test. A direct relation was found: The hot cracking susceptibility decreases with increasing number of grain boundaries across the width of the weld seam, i.e. along the effective load direction of transverse strain rates. It was shown, that the hot cracking susceptibility can be reduced by an optimisation of both the welding parameters and the alloying additives, which promote nucleation. 相似文献
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0 IntroductionAluminumalloyswithhighstrengthhavehighratiostrengthandratiorigidity ,andhavethewideapplicationprospectsinthefieldofaviationandaerospace .Butsuchalloyshavehighsusceptibilitytohotcrack ,widesoft enedzoneandpoorqualityinweldedjoint,thusloweringthejointstrengthgreatlyandrestrainingthefurtherap plicationoftheseweldedstructures .So ,manymethodswereputforwardtostrengthenaluminumalloyweldedjointwithhighstrength .Fromtheviewpointofmetal lurgy,theexperimentalmethodsforweldingthermalsimula… 相似文献
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AZ31B/LY12的搅拌摩擦焊研究 总被引:1,自引:0,他引:1
针对异种材料AZ31B镁合金与LY12铝合金进行了搅拌摩擦焊技术研究,结果表明,当选定恰当的焊接工艺参数时,AZ31B/LY12搅拌摩擦焊接是可行的,能得到外观形貌基本良好的接头.同时镁铝合金的片层结构由于材料的彼此挤压而相互挤入,发生明显的变形,从而导致焊接接头的力学性能较母材有所降低. 相似文献
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随焊冲击碾压法(weld with Trailing Impact Rolling,WTIR)是一种降低应力、减小变形防止热裂纹的新方法。文中分析了在前后冲击碾压轮作用下,焊缝金属塑性流动和应变场的变化规律,揭示了这种方法的机理。前轮周面内凹,迫使焊缝金属由焊趾处向焊缝中心流动,对处于脆性温度区间的焊缝金属施加一个横向挤压塑性应变,减小甚至抵消致裂的拉伸应变,防止了焊接热裂纹的产生。后轮缘稍向外凸,将焊缝金属冷却产生的压缩塑性变形充分碾开,减小了工件的应力和变形。试验结果表明,随焊冲击碾压能有效地防止焊接热裂纹的产生,将试件的纵向挠曲变形与横向收缩变形量控制到常规焊接状态的1/10和1/5左右,同时能将薄壁构件焊接残余应力控制到非常低的水平,甚至由拉应力状态转变为压应力状态,验证了应变场分析的正确性。 相似文献
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采用4043,5356,7055三种焊接材料对喷射成形7475铝合金TIG焊接头的热裂纹敏感性进行了研究,对接头的力学性能进行了测试,分析了接头的微观组织及裂纹的形貌、相组成.结果表明,采用5356焊丝时热输入对焊接热裂纹敏感性影响较大,高热输入时母材中的铜和锌向焊缝进行扩散和焊缝中的镁在熔合区形成α-Al,Al0.403Zn0.597和Al7 Cu3 Mg6相的低熔共晶组织,并在晶界和枝晶间形成偏析,在焊接应力的作用下在熔合区内产生了贯穿性热裂纹;低热输入时接头没有出现热裂纹,但强度只有184 MPa;而4043和7055两种焊丝的热裂纹敏感性较小. 相似文献
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利用有限元软件ABAQUS,对换热器管子与管板焊接残余应力进行数值模拟,获得了焊接接头残余应力的分布规律,比较了伸出角接头和内角接头的优劣.计算结果表明,内角接头残余应力比伸出角接头小.最大径向应力出现在管板表面的热影响区,对管板表面裂纹有主要影响.最大环向应力出现在焊缝根部,对管子与管板连接失效影响较大.相邻两换热管之间,由于后面换热管的焊接加热作用,使前面管子焊缝局部应力值下降,有利于降低应力腐蚀开裂的敏感性.研究结果为优化换热器管子与管板的焊接工艺、控制残余应力提供了理论依据. 相似文献
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对温差拉伸和随焊激冷配合使用控制铝合金薄板焊接变形的联合工艺进行了数值模拟和试验研究。数值分析表明 ,随焊激冷更倾向于在焊缝中心造成显著的纵向塑性拉伸 ,而温差拉伸则倾向于在近缝区造成显著的塑性拉伸。将二者配合使用 ,不仅可以靠温差拉伸将焊缝和近缝区在加热阶段形成的纵向塑性压应变控制在较低的水平 ,还可以靠随焊激冷增加冷却阶段的纵向塑性拉伸进一步抵消焊缝区已经形成的压应变。因而充分发挥二者的作用 ,有效地控制焊件的残余变形。试验研究与数值模拟得到的结论基本一致 ,随焊激冷和温差拉伸联合使用 ,可使 5 4 0mm× 3 0 0mm× 2mm的LY1 2CZ薄板焊后纵向挠曲由单独使用温差拉伸时的 2 .87mm和单独使用随焊激冷时的 4 .88mm降低到 0 .80mm的水平 相似文献