2219铝合金FSW焊缝摩擦塞补焊接头性能分析

采用顶锻式摩擦塞补焊方法,对8 mm厚2219-T87铝合金FSW焊缝进行了摩擦塞补焊试验研究,深入探讨摩擦塞补焊接头的微观组织、常温和低温力学性能、硬度及断口形貌变化特征. 结果表明,摩擦塞补焊接头具有明显的组织不均匀性,主要由塞棒区、塞棒热力影响区、再结晶区、母材热力影响区、热影响区和母材区组成;母材热力影响区晶粒具有显著变形特征, 其硬度最低为85 HV,是整个接头的薄弱部分. 摩擦塞补焊接头的常温和低温抗拉强度均达到FSW接头的80%以上,断后伸长率达到70%以上,其断裂模式为韧性特征.     

2219-T87铝合金拉锻式摩擦塞补焊接头组织及性能

对6 mm厚的2219-T87铝合金板进行了拉锻式摩擦塞补焊试验,对焊接接头的微观组织、显微硬度、抗拉强度及拉伸断口进行了观察与测试. 结果表明,采用优化的摩擦塞补焊工艺可实现2219-T87铝合金母材和2219-T87铝合金塞棒的冶金连接. 拉锻式摩擦塞补焊过程中,塞棒承受拉应力,应优化接头设计和焊接工艺参数从而防止塞棒被拉断. 未焊合是接头的主要缺陷,易出现在接头的近上表面处. 焊缝区发生明显软化,最低硬度出现在靠近连接界面的塞棒热力影响区,最低值为84.4 HV. 接头的抗拉强度可达326.4 MPa,断后伸长率可达4.45%,抗拉强度和断后伸长率分别为母材的71.7%和44.5%,拉伸断口呈韧窝形貌.     

铝合金搅拌摩擦焊缝摩擦塞补焊组织与力学性能

对2219-T87铝合金搅拌摩擦焊缝进行摩擦塞补焊工艺试验,对塞补焊接头的焊缝成形、显微组织、显微硬度和抗拉强度进行了观察和测试,对拉伸断口进行了扫描电镜观察.结果表明,在7 500 r/min的焊接转速和40~55 kN的焊接压力下可获得无缺陷摩擦塞补焊接头;塞补焊接头沿垂直于搅拌焊缝方向的最大抗拉强度和断后伸长率分别可以达到336 MPa和8%,分别相当于母材抗拉强度和断后伸长率的73.9%和66.7%;在母材和塞棒之间的底部结合面是最薄弱的区域,如何控制该区域的结合强度是影响摩擦塞补焊接头拉伸性能的关键因素.     

2219铝合金搅拌摩擦焊焊缝顶锻式摩擦塞补焊接头性能分析

采用顶锻式摩擦塞补焊方法对10 mm厚2219铝合金搅拌摩擦焊焊缝用2219铝合金塞棒进行了补焊,研究得出塞棒锥角大于塞孔锥角的配合方式能有效避免缺陷的产生。对塞补焊接头的微观组织、常温和低温力学性能、显微硬度和断口形貌进行了分析。结果表明,塞补焊接头分为塞棒区、焊核区、热力影响区、热影响区和母材区5部分,焊核为细小的等轴再结晶组织,热力影响区晶粒发生粗化长大和弯曲变形,热影响区组织晶粒结构与母材相似。塞补焊接头的低温抗拉强度和断后伸长率基本达到搅拌摩擦焊接头的性能。塞补焊接头显微硬度分析表明,焊核区硬度最高,最低硬度值出现在热力影响区。     

采用FSW与MIG工艺补焊6005A-T6铝合金的接头力学性能

针对6005A-T6铝合金型材搅拌摩擦焊接头缺陷补焊的应用要求,研究搅拌摩擦焊(FSW)补焊和熔化极气体保护焊(MIG)补焊工艺,对两种补焊接头的力学性能进行分析。结果表明:FSW补焊与MIG补焊方法均可以消除FSW接头缺陷,两种补焊接头的强度均达到无缺陷的FSW接头强度的88%以上,FSW补焊接头的平均抗拉强度为216.72 MPa,平均屈服强度为145.5 MPa,略高于MIG补焊接头的平均抗拉强度(206.2 MPa)和平均屈服强度(134.07 MPa)。两种补焊的接头硬度最低值都出现在热影响区,最高值都出现在母材区。     

焊后热处理对新能源汽车6063-T5散热器搅拌摩擦焊接头力学性能的影响

采用搅拌摩擦焊(friction stir welding,FSW)方法进行了新能源汽车6063-T5铝合金散热器的焊接,并进行了525℃×2 h固溶,200℃×6 h时效的焊后热处理,测试和分析了焊接接头的拉伸性能和冲击性能。结果表明,与母材相比,搅拌摩擦焊接头的抗拉强度、屈服强度、断后伸长率和冲击吸收功分别达到母材的82%、89%、86%、90%;焊后热处理接头的的抗拉强度、屈服强度、断后伸长率和冲击吸收功分别达到母材的101%、104%、98%、113%。焊后热处理明显提高了接头的力学性能。     

6061-T6/7075-T6异种铝合金搅拌摩擦焊接头组织与性能

利用搅拌摩擦焊实现了2 mm厚7075-T6/6061-T6异种铝合金连接,并对材料放置位置和转速对接头成形与组织性能的影响进行了分析. 结果表明,7075-T6铝合金置于前进侧时更有利于焊接过程中材料的迁移行为,焊缝成形及接头性能更优.当焊接速度为150 mm/min、转速为1 000 r/min时,可获得内部无明显缺陷、外观良好的异种铝合金接头;相较于母材,热力影响区的小角度晶界含量增加,焊核区发生动态再结晶,小角度晶界转化为大角度晶界;接头拉伸性能随转速的增加,呈现先增加后减小的趋势.接头的平均抗拉强度和断后伸长率分别达到231 MPa和4.0%. 接头的断裂位置位于6061侧焊核区,与接头硬度最小位置相吻合.     

6061-T6铝合金的静止轴肩搅拌摩擦焊工艺及组织性能

采用自主研制的静止轴肩搅拌摩擦焊工具系统成功获得了6061-T6铝合金的对接接头. 对该接头的焊缝成形、显微组织、硬度分布以及拉伸性能分别进行了试验研究. 结果表明,SSFSW工艺所得6061-T6铝合金接头具有非常美观的焊缝成形,与常规的FSW工艺相比,几乎没有出现焊缝减薄的现象;焊缝组织分区也有明显的不同,TMAZ非常窄,只有几百微米;接头的硬度呈"W"形分布;在转速1 000 r/min,焊速为200 mm/min时,接头的抗拉强度和断后伸长率达到最大,分别为母材的71.5%和44.6%;拉伸试样均断裂在热影响区,它是接头发生断裂的最薄弱区域.     

厚板铝/镁合金红外热源辅助搅拌摩擦焊力学性能与组织分析

分别采用常规搅拌摩擦焊和红外热源辅助搅拌摩擦焊,进行了AZ31B-H24镁合金与6061-T6铝合金的厚板异质搅拌摩擦焊,并进行了显微组织、物相组成和力学性能的测试与分析。结果表明,红外热源辅助搅拌摩擦焊细化了接头的组织,显著改善了合金的力学性能,使抗拉强度增加25.4%,屈服强度增加20.3%,伸长率增加2.4%;采用红外热源辅助FSW获得的上述异质接头的抗拉强度达到AZ31B-H24镁合金母材的90.3%,达到6061-T6铝合金母材的85.3%。     

铝合金静止轴肩搅拌摩擦焊组织非均质性对接头力学性能的影响

对6061-T6铝合金静止轴肩搅拌摩擦焊(stationary shoulder friction stir welded, SSFSW)接头组织非均质性与力学性能的相互影响进行了定量分析. 结果表明,SSFSW焊接接头存在明显的组织非均质性,表现在晶粒尺寸及形状、沉淀相种类及分布形态不同,其中沉淀相析出不同是影响力学性能差异的主要因素. 由于组织非均质性导致紧邻焊核区的热影响区软化严重,其硬度和抗拉强度在接头区域最低,分别为母材的60%和72%,为接头最薄弱部分. 由于沉淀强化和晶粒细化效应,焊核区的强度与塑性最好,而抗拉强度和断后伸长率分别达到母材的88%和215%. 随着与焊核区距离的增加,热影响区抗拉强度和屈服强度逐渐增加,断后伸长率不断降低.     

轴肩辅助加热6082铝合金摩擦塞补焊接头组织及力学性能

为了解决搅拌摩擦焊匙孔类体积型缺陷修复问题,在填充式搅拌摩擦焊基础上,采用轴肩与母材摩擦辅助加热的方法对同种材料铝合金匙孔类缺陷进行摩擦塞补焊,在不同的塞棒转速下得到了成形良好的塞补焊接头.?结果表明,由于热输入和材料形变作用,接头不同区域组织发生了明显变化.?不同塞棒转速下接头组织及分布状态相似.?一个完整的塞补焊接...     

Tensile properties of 6061-T6 friction stir welds and constitutive modelling in transverse and longitudinal orientations

Tensile stress–strain properties of Al alloy 6061-T6 (AA6061-T6) and its butt welds produced by the friction stir welding (FSW) process were characterized in two different loading orientations. AA6061-T6 FS welds were made under three sets of welding conditions. Micro-hardness tests were performed to investigate microstructural evolution during the FSW process. Flat tensile specimens were machined normal and parallel to the weld line. Transvers and longitudinal tensile tests were run on the base material (AA6061-T6) and its FS welds in an Instron testing machine. The strength and ductility (or fracture strain) of the FS welds observed in the transverse orientation were substantially less than those in the longitudinal orientation. Constitutive modelling of uniaxial tensile stress–strain behaviour in both orientations was presented using a rate-independent Ludwik equation. In addition, microstructures of the base material and its FS welds were examined with optical and transmission electron microscopy to discuss the decrease in the flow stress level and the increase in the strain hardening rate of the FS welds.     

Effect of post-weld heat treatment on joint properties of dissimilar friction stir welded 2024-T4 and 7075-T6 aluminum alloys

The effect of post-weld heat treatment on dissimilar friction stir welded AA7075 and AA2024 joints was studied. After welding in constant parameters, solution heat treatment and various aging treatments were given to the welded joints. Microstructural and phase characterizations were done using optical microscope, SEM, FE-SEM, XRD and EDS techniques. Finally, mechanical properties of post-weld heat treated joints were evaluated and compared with as-welded joints. Results show that both 2024-T6 and 7075-T6 post-weld heat treatment procedures considerably improve the mechanical strength of the welded joint, with higher strength obtained for the 7075-T6 procedure, in comparison with the as-welded joint. This is explained by the formation of fine precipitates during the aging process, despite the abnormal grain growth. Fracture occurs at the interface between thermo-mechanical affected zone (TMAZ) and heat affected zone (HAZ) on the retreating side (AA7075) of as-welded joint, while by applying post-weld heat treatment fracture location shifts towards the stir zone (SZ) of the welded joint. Also, for post-weld heat treated samples, fracture surface is predominantly inter-granular, while in as-weld joint, fracture surface is mostly trans-granular. This is explained by dissolution and coarsening of precipitates within grains in post-weld heat treated joints.     

搅拌摩擦焊AA7075-T651铝合金接头的疲劳裂纹扩展(英文)

研究12 mm厚AA7075-T651铝合金板搅拌摩擦焊接头的疲劳裂纹扩展行为。从搅拌摩擦焊接头以及母材中截取试样,对试样进行疲劳裂纹扩展实验。对搅拌摩擦焊接头以及母材的横向拉伸性能进行评估。用光学显微镜和透射电镜分析焊接接头的显微组织。用扫描电镜观察试样的断裂表面。与母材相比,焊接接头的ΔKcr降低了10×10-3 MPa·m1/2。搅拌摩擦焊AA7075-T651接头的疲劳寿命明显低于母材的,其原因可归结于焊缝区的析出相在搅拌摩擦焊接过程中的溶解。     

Mechanical properties of friction stir welded Al alloys with different hardening mechanisms

The mechanical properties of precipitation hardened Al 6061-T651 and Al 7075-T6 and strain hardened Al 5083-H32, friction stir welded with various welding parameters, were examined in the present study. 4 mm thick Al 6061-T651, Al 7075-T6, and Al 5083-H32 alloy plates were used for friction stir welding (FSW) with rotating speed varied from 1000 to 2500 rpm (rotation per minute) and welding speed ranging from 0.1 to 0.4 mpm (m/min). Each alloy displayed slightly different trends with respect to the effect of different welding parameters on the tensile properties of the FSWed Al alloys. The tensile elongation of FSWed Al 6061-T651 and Al 7075-T6 tended to increase greatly, while the tensile strength decreased marginally, with increasing welding speed and/or decreasing rotating speed. The tensile strength and the tensile elongation of Al 6061-T651 decreased from 135 to 154 MPa and 10.6 to 17.0%, respectively, with increasing welding speed from 0.1 to 0.4 mpm at a rotating speed of 1,600 rpm. Unlike the age-hardened Al 6061-T651 and Al 7075-T6, the strain-hardened Al 5083-H32 showed no notable change in tensile property with varying welding parameters. The change in the strength level with different welding parameters for each alloy was not as significant as the variation in tensile elongation. It was believed that the tensile elongation of FSWed Al alloys with varying welding parameters was mainly determined by the coarse particle clustering. With respect to the change in tensile strength during friction stir welding, it is hypothesized that two competing mechanisms, recovery by friction and heat and strain hardening by plastic flow in the weld zone offset the effects of different welding parameters on the tensile strength level of FSWed Al alloys.     

Effect of welding heat input and post-weld aging time on microstructure and mechanical properties in dissimilar friction stir welded AA7075–AA5086

The effects of welding heat input and post-weld heat treatment on the mechanical and microstructural aspects of dissimilar friction stir welds of age-hardened AA7075-T6 and strain hardenable AA5086-H32 aluminium alloys were investigated. X-ray diffraction (XRD) residual stress analysis and tensile testing together with optical metallography and transmission electron microscopy (TEM) were performed to assess the effects of process parameters on welded joints. It was discovered that joints produced without heat sink exhibited more homogeneous stir zones than other joints. Of the natural aging time studied, higher amount of solid solution during rapid cooling of welds produced higher driving force for increase in hardness in the AA7075 side during natural aging. Natural aging within stirring zone and thermo-mechanical affected zone of AA7075 side resulted in a 10 to 25 MPa reduction in the residual stress in these zones; its effect decreased considerably in the welds performed without heat sink. In addition, natural aging had no noticeable effect on the joint strength.     

2219-T87铝合金搅拌摩擦焊接头组织与力学性能

采用搅拌摩擦焊方法对8mm厚2219-T87铝合金进行了焊接.对接头的宏观形貌、微观组织、显微硬度及断口形貌进行了分析.结果表明,焊核区为细小的等轴晶粒,晶粒尺寸远小于母材;热机影响区发生了弯曲变形;热影响区组织出现了明显粗化.前进边热机影响区和焊核区形成明显分界线,后退边相对模糊.搅拌摩擦焊对接头各区域沉淀相分布形态有重要影响.接头室温拉伸强度可以达到母材的70%以上.沿焊缝横截面的显微硬度的分布显示,硬度最低点位于后退侧热影响区区域,断裂位置位于后退侧热影响区处,接头的断裂形式为韧性断裂.