AA2219-T87铝合金双轴肩搅拌摩擦焊的腐蚀行为

采用电化学腐蚀和浸泡腐蚀试验对双轴肩搅拌摩擦焊AA2219-T87型铝合金的不同区域进行了腐蚀研究。结果表明,焊缝区具有最高的耐腐蚀性,母材的耐腐蚀性最差。母材中析出相的体积分数最高,越靠近焊核,析出相回溶数量越多。焊核区由细小的等轴晶组成,只存在少量θ相     

2219铝合金搅拌摩擦焊接头晶间腐蚀分析

采用晶间腐蚀试验研究了2219铝合金搅拌摩擦焊接头的晶间腐蚀行为,结合接头显微组织、微观硬度、腐蚀形貌及腐蚀深度,分析母材与焊核区的差异,并对接头晶间腐蚀机理进行了初步的探讨.结果表明,焊核区为细小的等轴晶组织,且接头上表面焊核区的晶粒要大于下表面焊核区的晶粒;母材区硬度最高,下表面焊核区硬度最低;焊核区的耐蚀性优于母材,且上表面焊核区耐蚀性优于下表面焊核区,母材最大腐蚀深度为145.9 μm,上表面焊核区及下表面焊核区最大腐蚀深度为46.3 μm和84.1 μm.     

6061铝合金搅拌摩擦焊接头组织及性能

对厚度6 mm的6061铝合金进行了搅拌摩擦焊对接焊,采用光学显微镜、扫描电子显微镜、拉伸试验机及电化学工作站等设备对焊接接头的金相组织、断口形貌、拉伸性能和腐蚀性能进行了测试和分析。结果表明,当焊接速度为80 mm/min、旋转速度在600～1 500 r/min之间时,焊接接头的外观良好,无明显缺陷。随着旋转速度的增加,焊核区晶粒呈现出先减小后增大的现象。当旋转速度为1 200 r/min时,焊核区的晶粒最细小,焊接接头的抗拉强度和断后伸长率最高,分别为168 MPa和14.7%,焊缝强度达到了母材的81.9%,焊接接头的断裂形式为以韧性断裂为主的韧-脆混合断裂模式。随着旋转速度增大,搅拌摩擦焊接头的耐腐蚀性能呈现先上升后下降的趋势,当搅拌头旋转速度为1 200 r/min时,焊接接头的耐腐蚀性能最好,其腐蚀电流密度最小为2.4×10-5 A/cm2。创新点： 研究了旋转速度焊接工艺参数与搅拌摩擦焊焊接头耐腐蚀性能之间的关系。     

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.     

6005A铝合金搅拌摩擦焊接头的晶间腐蚀行为

对6005A铝合金搅拌摩擦焊接头的晶间腐蚀行为进行了研究.结果表明,母材的晶间腐蚀倾向最大,热影响区(HAZ)次之,焊核区(NZ)和热力影响区(TMAZ)的晶间腐蚀倾向最低.结合场发射扫描电镜、高分辨透射电镜分析解释了接头不同区域的腐蚀行为:母材的晶间腐蚀是两组微电池效应的结果,即晶界析出相/沉淀无析出带(PFZ)和铝基体/PFZ;HAZ内晶界析出相的数量的减少、间距的变大及晶内Q'相的析出显著改善了该区的晶间腐蚀性,但晶内Q'相的析出也引起了点蚀的发生;NZ和TMAZ内绝大部分的合金元素固溶于基体,抑制了晶间腐蚀的发生.     

Effect of cooling conditions on corrosion resistance of friction stir welded 2219-T62 aluminum alloy thick plate joint

Friction stir welding (FSW) with water cooling and air cooling was used to weld 2219-T62 aluminum alloy joints with a thickness of 20 mm. The effect of cooling conditions on the corrosion resistance of joints in 3.5% NaCl solution was investigated using the open circuit potential (OCP), the potentiodynamic polarization, and the corrosion morphology after immersing for different time. And the precipitates distribution was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results reveal that the weld nugget zone (WNZ) owning positive potential, lower corrosion current density and fine and uniform precipitates, is much more difficult to corrode than the heat affected zone (HAZ) and the base metal (BM). Compared with air-cooled joint, the water-cooled joint has better corrosion resistance. In addition, the results of microstructure observation show that the potential, distribution and size of second phase particles determine the corrosion resistance of FSW AA2219 alloy joints in chlorine-contained solution.     

焊接方法对AA2219铝合金接头性能的影响(英文)

使用钨电极惰性气体保护焊接、电子束焊接和搅拌摩擦焊接技术制备无填充金属的AA2219铝合金对焊接头。研究三种焊接工艺对材料拉伸、疲劳和腐蚀行为的影响。使用光学和电子显微镜研究显微结构。结果表明,与钨电极惰性气体保护焊和电子束焊接相比,搅拌摩擦焊制备的接头具有较高的拉伸和疲劳性能与较低的耐蚀性能,这主要是由于其中的细化晶粒和均匀分布的强化析出相所引起的。     

2219-T87厚板搅拌摩擦焊沿厚度方向的性能差异

采用搅拌摩擦焊方法对35 mm厚的2219-T87高强铝合金进行了单道对接焊.结果表明,焊缝的抗拉强度可达274 MPa,且断裂于焊核区.用螺旋形搅棒焊接厚板时,焊接速度较慢,焊核区上部组织因温度较高,同时在螺旋产生的向下泵吸作用下,会产生比较粗大的疏松组织;而焊核区中下部组织则因温度较低,并在螺旋推力作用下形成比较细小的致密组织.焊核区上部的显微硬度存在一个下陷区,而中下部的显微硬度变化较为平缓.焊接厚度过大时,螺旋搅棒的泵吸作用引起焊核区上部组织疏松,并使其显微硬度下陷,是造成厚板搅拌摩擦焊缝强度不高且断裂于焊核区的原因.     

Microstructural characterization and corrosion behavior of multipass friction stir processed AA2219 aluminium alloy

Multipass friction stir processing of AA 2219-T87 aluminium alloy to a depth of 2 mm in a 5 mm plate resulted in fine α-Al grains, reduction and dissolution of both eutectic phase (CuAl₂) and the strengthening precipitates (CuAl₂). Anodic polarization and electrochemical impedance tests in 3.5% NaCl showed an improved corrosion resistance of the processed alloy, which increased with the number of passes. Salt spray and immersion tests also showed improved resistance to corrosion. The increased resistance to corrosion is attributed to the dissolution of CuAl₂ particles, which was established by XRD and DSC studies.     

2219铝合金搅拌摩擦焊接头腐蚀行为

采用晶间腐蚀试验和剥落腐蚀试验研究了2219铝合金搅拌摩擦焊接头的腐蚀行为,结合金相显微镜、扫描电镜及能谱仪等分析手段研究了接头腐蚀后的表面形貌和腐蚀产物的成分,并对接头腐蚀机理进行了初步的探讨.结果表明,搅拌摩擦焊焊核区耐蚀性比母材高;腐蚀从点蚀开始,逐渐发展为晶间腐蚀和剥落腐蚀的全面腐蚀形貌;接头组织成分的均匀化,降低了材料形成局部腐蚀原电池的倾向,使得电位正向移动,接头耐蚀性增强.     

2219铝合金FSW-VPPA交叉焊缝组织与力学性能

采用搅拌摩擦焊(FSW)和变极性等离子弧焊(VPPA),在2219铝合金6 mm板上沿着相互垂直的方向施焊以形成FSW-VPPA交叉焊缝.对交叉焊缝的组织形貌进行了观察分析,并对交叉焊缝和单一VPPA焊缝的拉伸力学性能及断口形貌进行了对比研究.结果表明,交叉焊缝微观组织呈现不对称、不均匀的特征,其焊缝区组织主要由α-Al基体和(α-Al+CuAl2)共晶组成,熔合区以及近熔合区的热影响区易于出现聚集性气孔;熔合区附近气孔发生率增加导致交叉接头抗拉强度及断后伸长率明显下降.     

The effect of welding parameters on the corrosion behaviour of friction stir welded AA2024-T351

The effect of welding parameters (rotation speed and travel speed) on the corrosion behaviour of friction stir welds in the high strength aluminium alloy AA2024-T351 was investigated. It was found that rotation speed plays a major role in controlling the location of corrosion attack. Localised intergranular attack was observed in the nugget region for low rotation speed welds, whereas for higher rotation speed welds, attack occurred predominantly in the heat-affected zone. The increase in anodic reactivity in the weld zone was due to the sensitisation of the grain boundaries leading to intergranular attack. Enhancement of cathodic reactivity was also found in the nugget as a result of the precipitation of S-phase. The results were compared with samples of AA2024-T351 that had been heat treated to simulate the thermal cycle associated with welding, and with samples that had been exposed to high temperatures for extended periods to cause significant over-ageing.     

搅拌摩擦焊工艺参数对2024-T351铝合金搭接焊接头成形质量和力学性能的影响

研究搅拌摩擦焊时R/v比对2024-T351铝合金焊接质量的影响。搅拌摩擦焊时搅拌针的旋转速度设定为750、950和1180 r/min,焊接速度在73~190 mm/min内变化,对应的R/v比在5.00~10.27内。采用各种无损（外观检测、X射线检测）和有损（金相观察、拉伸实验和硬度测量）检测手段对焊接试样进行分析。在所有的试样中,搅拌摩擦焊中各种典型的区域都有存在,不同的区域其晶粒尺寸不同。接头的拉伸性能为基材的52.2%~82.3%。在R/v比为8.06,10.17和10.27时焊接质量最佳。其原因是在最佳搅拌速度下,材料围绕搅拌针充分流动,从而能够填充其中产生的空隙,阻止空洞的生成。结果还表明,R/v 比对接头的硬度分布、洋葱样形状、裂纹的萌生和扩展都有影响。     

镁/铝层合板FSW接头微观组织及力学性能

文中采用搅拌摩擦焊 (FSW)方法对Mg/Al层合板进行单面、双面对接方式焊接,对接头的微观组织和力学性能进行测试. 结果表明,随着焊接速度和搅拌针旋转速度的增加,焊缝表面成形良好,接头不同区域未见气孔、裂纹等缺陷,物相主要由Mg₁₇Al₁₂,Mg₂Al₃和MgAl等组成,接头部位的晶粒尺寸得到明显细化,产生了动态再结晶,金属间化合物的形成有利于动态再结晶的形核. Mg/Al层合板双面FSW焊接头的拉伸强度和断后伸长率高于单面焊接接头的强度和断后伸长率,主要是由于接头部位金属间化合物的数量和分布不同,抑制接头部位金属间化合物的形成有利于提高Mg/Al层合板FSW接头的性能.     

7075铝合金与H68黄铜的搅拌摩擦焊组织分析

采用金相显微镜对7075铝合金与H68黄铜异种材料搅拌摩擦焊接头组织进行观察、采用X射线衍射仪（XRD）对焊接接头中相结构进行分析,并采用显微硬度计对焊接接头硬度分布进行测试.结果表明,搅拌针的旋转频率为1 100 r/min,焊接速度为80 mm/min时,焊接接头未形成金属间化合物,焊核区晶粒细化,且显微硬度值增加...     

镁铝异种金属搅拌摩擦焊搭接接头组织与性能分析

采用搅拌摩擦焊技术对异种金属铝合金5083和镁合金AZ31进行了搭接焊试验.对接头的力学性能、组织形貌及断口形貌进行了观察和分析.结果表明,在铝板置于上层、搅拌针长度小于铝板板厚的情况下,使用合适的工艺参数,这两种轻合金可以获得抗剪性能良好、界面结合紧密、无缺陷的搭接接头,从而使镁板和铝板通过由一定金属间化合物组成的界面区过渡层形成了良好的连接;接头都断裂于界面结合处,铝侧是由塑性撕裂导致的"小坑"组成,而镁侧主要为河流状花样;在界面中心区出现了明显的硬度升高现象.     

Rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys

The tensile rupture locations of friction stir welded joints of AA2017-T351 and AA6061-T6 aluminum alloys were examined. The experiments show that the rupture locations of the joints are different for the two aluminum alloys, which are influenced by the welding parameters. When the joints are free of welding defects, the AA2017-T351 joints are ruptured in the weld nugget adjacent to the thermo-mechanically affected zone on the advancing side and the rupture surfaces appear as oval contours of the weld nugget, while the AA6061-T6 joints are ruptured in the heat affected zone on the retreating side and the rupture surfaces are inclined at a certain degree to the bottom surfaces of the joints. When welding defects are present in the joints, the AA2017-T351 joints are ruptured in the weld center, while the AA6061-T6 joints are ruptured on the retreating side near the weld center. The rupture locations of the joints are dependent on the internal structures of the joints and can be explained through them.     

Characteristics and corrosion performance of 80Ni-20Cr coating deposited by on-site thermal spraying

New controlled atmosphere on-site spraying systems were developed to deposit a high-quality coating with superior resistance to wet corrosion. Characteristics and corrosion resistance of coatings deposited by arc and flame spraying of wire in argon gas were compared with those of coatings deposited by conventional and low-pressure plasma techniques. It was found that the coating deposited by the arc spraying of wire in argon gas is free of oxides and possesses excellent corrosion resistance in chloride and acid solutions. The coating suffers slight pitting and crevice corrosion associated with the isolated pores and electric potential paths. Corrosion resistance was improved by using a modified spraying system.     

镁合金表面冷喷涂铝合金的界面扩散行为

采用冷喷涂技术在镁合金表面制备了快凝Al-12Si-3Fe-3Mn-2Ni合金粉末涂层,观察了涂层与基体合金界面形态,试验研究了热处理温度和保温时间对涂层与基体之间相互扩散的影响.结果表明,采用冷喷涂技术制备的快凝Al-12Si-3Fe-3Mn-2Ni合金粉末涂层,经热处理后涂层更加致密、均匀,涂层中的Al元素和基体中的Mg元素均发生互扩散;基体中的Mg元素向涂层方向的扩散量要大于涂层中的Al元素向基体方向的扩散量;随着温度的提高和时间的延长,基体和涂层之间的Mg,Al元素扩散程度均提高;但是当温度提高到300℃,时间延长到3h后,其扩散层变化微小.涂层和基体合金中的其它元素扩散量较少.     

铝合金平板搅拌摩擦焊接应力变形分析

针对6056-T6铝合金平板进行搅拌摩擦焊接和试板变形检测试验.并用数值方法对试板变形进行模拟,考察了模拟温度、应力场分布和试板变形情况,对试验和模拟温度、变形进行比较.结果表明,在文中条件下,沿焊缝长度方向试板产生下挠,最大变形量6.3 mm;沿试板宽度方向试板相对发生上拱,最大变形量4.5 mm,模拟与实测变形趋势非常吻合.纵向残余应力在焊缝中心线两侧非对称性分布,前进侧大于回转侧.