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Effects of laser shock processing on mechanical properties of laser welded ANSI 304 stainless steel joint 总被引:1,自引:0,他引:1
Yongkang Zhang Lei Zhang Kaiyu Luo Guifang Sun Jinzhong Lu Fengze Dai Junwei Zhong 《机械工程学报(英文版)》2012,25(2):285-292
With the rapid development of engineering component with integration,high-speed and multi-parameter,traditional techniques haven’t met practical needs in extreme service environment.Laser welding,a new welding technology,has been widely used.However,it would generate the drop of mechanical properties for laser welded joint due to its thermal effect.Laser shock processing(LSP) is one of the most effective methods to improve the mechanical properties of laser welded ANSI 304 stainless steel joint.In this paper,the effects of LSP on the mechanical properties of laser welded ANSI 304 stainless steel joint have been investigated.The welded joint on the front of the tensile samples is treated by LSP impacts,and the overlapping rate of the laser spot is 50%.The tensile test of the laser welded joint with and without LSP impacts is carried out,and the fracture morphology of the tensile samples is analyzed by scanning electron microscope(SEM).Compared with the yield strength of 11.70 kN,the tensile strength of 37.66 kN,the yield-to-tensile strength ratio of 0.310 7,the elongation of 25.20%,the area reduction of 32.68% and the elastic modulus of 13 063.876 MPa,the corresponding values after LSP impacts are 14.25 kN,38.74 kN,0.367 8,26.58%,42.29% and 14 754.394 MPa,respectively.Through LSP impacts,the increasing ratio of the yield strength and tensile strength are 121.79% and 102.87%,respectively;the elongation and area reduction are improved by 5.48% and 29.38%,respectively.By comparing with coarse fracture surface of the welded joint,the delamination splitting with some cracks in the sharp corner of the welded joint and asymmetric dimples,LSP can cause brighter fracture surface,and finer and more uniform dimples.Finally,the schematic illustration of dimple formation with LSP is clearly described.The proposed research ensures that the LSP technology can clearly improve the yield strength,tensile strength,yield-to-tensile strength ratio,elongation,area reduction and elastic modulus of the welded joint.The enhancement mechanism of LSP on laser welded ANSI 304 stainless steel joint is mainly due to the fact that the refined and uniform dimples effectively delay the fracture of laser welded joints. 相似文献
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TC4钛合金精密焊接工艺研究 总被引:4,自引:0,他引:4
针对TC4钛合金,采用电子束焊接和激光束焊接两种方法,对焊深及其波动,焊接质量,焊接变形等方面进行了分析,获得了外观成型良好,色泽正常的焊接接头,经过X射线探伤,焊缝内部质量达到国际GB3233-87Ⅱ级要求,实现了TC4钛合金的精密焊接。 相似文献
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对TC4钛合金单面修饰激光焊接接头进行激光冲击强化,对比强化前后焊接接头的疲劳寿命,在光学显微镜和扫描电镜下观察断口疲劳断裂特征,并从焊接接头的显微硬度、微观组织、残余应力分布等方面综合分析激光冲击强化对TC4钛合金单面修饰激光焊接接头的强化机理。试验结果表明:未强化和强化试样均在焊缝咬边处萌生疲劳裂纹,强化试样疲劳寿命是未强化试样疲劳寿命的3.77~9.15倍,强化试样焊缝咬边处马氏体细化,显微硬度提高,焊缝表面呈残余压应力分布,焊缝咬边处残余压应力达-564.37±9.85MPa。晶粒细化和高幅值残余压应力综合作用下抑制了焊缝咬边处疲劳裂纹的萌生,且增大了裂纹扩展阻力,从而提高了焊接接头疲劳性能。 相似文献
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TiNi形状记忆合金/钛合金异种材料激光焊 总被引:1,自引:0,他引:1
由于TiNi合金与钛合金的物理和化学性能差异较大,故其焊接性较差,焊缝区易形成大量的金属间化合物并产生裂纹。为实现上述材料的良好连接、提高接头性能,本文对采用激光焊连接0.2mm厚TiNi形状记忆合金和TC4钛合金异种材料进行了探索。分别采用直接对接焊和手工填丝焊的方法,研究了焊接接头的微观组织和力学性能。结果表明,直接对接焊时焊缝中心产生了纵向裂纹;手工填丝焊则通过合适的焊接工艺,改善了焊缝成形,避免了裂纹的产生。较优的焊接工艺参数为功率百分比18%、脉冲宽度3ms、脉冲频率3Hz;在界面区,Ni与TC4形成的过渡层宽度约为2μm,Ni与TiNi形成的过渡层宽度约为0.5μm。接头最大抗拉强度为332MPa,断裂位置发生在靠近TiNi侧的熔合线附近。 相似文献
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激光冲击强化对TC17表面硬度的影响 总被引:3,自引:0,他引:3
TC17钛合金叶片耐磨性较差,在航空发动机恶劣的使用环境下受到冲刷磨损的作用易引发疲劳断裂。研究利用激光冲击强化技术对TC17钛合金进行表面强化,结果表明:激光冲击强化能够显著提高TC17材料硬度,提升材料抗冲刷磨损性能。从不同冲击参数强化后硬度测试结果得出,功率密度4GW/cm2、冲击三次为TC17钛合金最佳的激光冲击强化工艺参数,其硬度提高幅度达到10%以上,并且影响深度超过1mm。激光冲击强化过程中引入的表层晶粒纳米级细化及次表层高密度位错是材料硬度提高的主要原因。 相似文献
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电子束焊接在齿轮加工中的应用 总被引:1,自引:0,他引:1
对电子束焊接的特点、工艺要求进行了简述,并通过实例说明这种焊接方法在齿轮加工中的应用场合,采用电子束焊接时各齿轮组件的加工工艺要求及工艺过程。实验结果表明,该工艺扩大了设备的加工能力,提高了设备的利用率。 相似文献
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LF6铝镁合金电子束焊接接头的性能与组织初探 总被引:2,自引:0,他引:2
分析电子束焊接LF6铝镁合金的焊缝微观组织,研究焊缝中Mg合金元素的烧损现象、焊接接头的力学性能和焊接热裂纹等问题,结果表明,电子束焊接LF6铝镁合金,其焊缝组织为微细等轴晶,熔合线附近为胞状树枝晶;Mg合金元素在焊缝上部和中心区有较大的蒸发损失;焊接接头存在一定的软化,其抗拉强度为母材的91.2%,除延伸率比母材高外,断面收缩率和冲击韧性值与母材相比均有所降低;在合适的参数匹配下,焊缝不会出现热裂纹以及氧化膜所导致的熔合不良与夹渣等问题。 相似文献
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激光冲击成形集板材成形和材料改性于一体,利用激光诱导高幅冲击波的力效应使板料产生塑性变形,是一种无模、柔性成形新工艺。本文使用商业有限元分析软件ABAQUS进行了钛合金板料激光冲击成形过程的仿真研究,分析了钛合金板料厚度、激光能量、约束孔径、激光光斑间隔四种因素对材料变形量和应力应变的影响。研究表明:随着板料厚度的增加,板料变形范围逐渐减小,变形量先减小后增大;随着激光能量的增大,材料的变形量线性增加;激光约束边界孔径越大,板料变形量越大;适当的光斑间隔并不会对零件成形精度造成较大影响,在满足精度要求的条件下,为提高效率可以考虑采用间隔光斑进行冲击成形。 相似文献
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钛合金TC4放电加工电极损耗研究 总被引:1,自引:0,他引:1
针对钛合金TC4在火花油中放电加工电极损耗大的问题,以蒸馏水和火花油为工作介质,进行了钛合金TC4的放电加工试验,分析比较了两者的电极绝对损耗量和相对损耗率的差异,并从加工波形和加工后电极的表面微观形貌及主要成分等几个方面研究了电极损耗机制。结果表明:蒸馏水的绝缘性较差,而流动性和冷却性好,消电离较充分,改善了极间状态,加工稳定,使加工效率大大提高;另外加工过程中产生的少量氧化钛和从工件飞溅的蚀除产物附着在电极表面,形成覆盖层,有效抑制了电极损耗。其电极绝对损耗与火花油加工时相差不大但相对损耗却大大降低。 相似文献
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TC4板孔冷挤压强化残余应力分布与疲劳寿命 总被引:1,自引:0,他引:1
开展了不同挤压量下TC4钛合金板孔冷挤压强化有限元仿真研究,得到了挤压强化后最小截面的切向残余应力分布规律,分析了挤压量对受载试样孔边应力分布的影响,探讨了挤压量、残余应力和疲劳增益三者之间的内在关系。采用开缝衬套冷挤压强化工艺对TC4带孔板件进行冷挤压和疲劳验证试验。研究结果表明,挤压强化后的孔边切向压缩残余应力可以有效降低孔周应力集中程度,优化受拉试样最小截面应力分布,改变裂纹源的位置并延长疲劳裂纹的萌生和扩展寿命,有效提高试样疲劳寿命。综合仿真和疲劳试验得到TC4板孔最优挤压量为4%。 相似文献
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S. Malarvizhi K. Raghukandan N. Viswanathan 《The International Journal of Advanced Manufacturing Technology》2008,37(3-4):294-301
Aluminum alloy 2219 (Al-6.5%Cu) is a favourite age hardenable alloy for aerospace applications because of its excellent welding
characteristics. Though AA2219 has got an edge over its 6000 and 7000 series counterparts in terms of weldability, it also
suffers from poor joint strength when welded. In this investigation an attempt has been made to improve the welded joint strength
through post weld aging treatment. This paper presents the effect of post-weld aging treatment on tensile properties of electron
beam welded AA2219 aluminum alloy. Square butt joints were fabricated using an electron beam welding (EBW) machine of 100 kV
capacity. The joints were given post-weld artificial aging treatment. Tensile tests were carried out using 100 kN, electro-mechanical
controlled universal testing machine. It is found that the post-weld aging treatment is beneficial for improving weld metal
hardness and tensile properties. This is mainly due to the uniform distribution of CuAl2 precipitates in the weld metal region in post-weld aged joints compared to as welded joints as evident from weld metal microstructure. 相似文献
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为了研究激光冲击强化对LZ50车轴钢疲劳性能的影响,对LZ50车轴钢车轴试样进行激光冲击强化处理并在JD-1轮轨模拟试验机上进行了旋转弯曲疲劳试验。结果显示:采用不同参数激光冲击强化处理的2个试样,硬度分别增大18%和27%;对LZ50车轴钢试样的过盈配合面进行激光冲击处理后产生了塑性变形层,形成了较高的残余压应力;试验后试样过盈配合表面两侧区域都可见明显的环形损伤带,出现了以剥落和犁沟为特征的磨损形貌,损伤机制为磨粒磨损、氧化磨损和剥层。激光冲击前后试样断口形貌特征相似,疲劳源呈多源性;在裂纹扩展区域段观察到大量的准解理小面,属于脆性穿晶断裂;瞬断区内出现大量韧窝和二次裂纹。激光冲击强化处理显著提高了车轴钢的疲劳寿命,不同激光冲击强化参数处理的2个车轴试样疲劳寿命比未处理试样疲劳寿命分别提高31%和21%。 相似文献
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为研究陶瓷刀具切削钛合金的磨损机理,采用CC6060陶瓷刀片对TC4钛合金进行了干式车削试验。结果表明:陶瓷刀具干式切削TC4钛合金时,磨损形貌以前刀面月牙洼磨损、后刀面沟槽磨损和刀尖破损为主,磨损机理主要是粘结磨损和氧化磨损。随着切削速度的增加,刀具磨损加剧,刀具寿命降低。CC6060陶瓷刀片干式切削钛合金时的使用寿命很低,不适于干式切削钛合金。 相似文献