数值模拟在镁合金焊接接头深冷处理中的应用

利用所建立的有限元模型,对焊接接头进行深冷处理前后的温度场分析,再把模型转化成结构单元进行应力应变场分析。计算结果表明:深冷处理后,受焊接热源影响的焊缝及附近区域横向残余应力和纵向残余应力均增大,距焊缝较远的母材区产生了预压应力;深冷处理后,横向和纵向残余变形均减小。     

镁合金焊接接头耐腐蚀性能研究现状

对近年来镁合金及其焊接接头腐蚀性能的研究现状和最新成果与进展进行了总结,指出了目前在镁合金焊接接头腐蚀研究领域存在的问题与不足,最后分析了镁合金焊接接头腐蚀的研究方向和工作重点。     

高速列车用6005A合金焊接接头组织与性能研究

采用进口5356焊丝对国产6005A铝合金进行熔化极惰性气体保护焊，对焊接接头的力学性能和显微组织进行了研究。结果表明，6005A铝合金焊接接头的力学性能低于基体的性能，热影响区内的软化区是焊接接头的最薄弱环节，强化相粒子发生过时效而粗化是形成软化区的根本原因。     

Mg-1Al-3Sn镁合金搅拌摩擦焊接试验研究

为了研究Mg-1Al-3Sn镁合金搅拌摩擦焊工艺性能,采用不同的旋转速度和焊接速度进行了平板对接搅拌摩擦焊接试验。结果表明,在较宽的焊接工艺参数范围内,可以获得无缺陷的焊接接头,接头效率在80.5~91.9%之间。     

外场复合电弧熔钎焊接镁合金和不锈钢异种接头的微观组织和机械性能的研究

本文采用一种新型的外场复合电弧熔钎焊接镁合金/不锈钢异种接头,其中焊丝采用4047铝硅焊丝。利用光学显微镜、扫描电镜、EDS和微观硬度测试来观测钎焊接头的微观组织和成分。结果表明,在外场复合的情况下,镁合金和不锈钢能形成良好的搭焊接头,外加磁场的存在能够促进焊缝金属元素的扩散,影响液态镁合金和钎料在不锈钢表面混合时的流动性和表面润湿性能,改变熔池的结晶状态,细化晶粒,抑制微裂纹,在0～0.5T的磁场强度范围内,随着外加磁场强度的增加,焊接接头的硬度和强度会得到显著地提高。     

7005铝合金型材焊接接头组织与性能

研究了大型车辆用７００５铝合金型材熔化极惰性气体保护焊（ＭＩＧ）焊接接头的显微组织和学性能，结果表明：７００５铝合金型材焊接接头最薄弱环节是焊道处，其次是焊接热影响区内的软化区；焊道为通常的铸态组织，紧挨着焊道的是狭窄的半熔化区，随后通过热影响过渡到基材区；焊接接头热影响区的硬度随停放时间的处长２，硬度值显著提高，表现出明显的自然时效强化效应，并对焊接接头不同区域的显微组织特征、性能变化及软化区形     

高等级管线钢焊接热影响区软化研究现状

介绍了高等级细晶粒管线钢焊接热影响区软化现象及其对接头性能影响的研究现状,对于高等级管线钢焊接工艺的制定及钢种的合金化设计有一定指导意义。     

镁合金搅拌摩擦焊的研究现状与展望

镁合金具有密度低、比强度高、导热性好等显著优点,在汽车、轨道交通和兵器等行业中的应用前景非常广阔,而传统的铆接和熔化焊等连接方法质量较差,从而限制了其应用。作为有色金属"焊接专家"的搅拌摩擦焊,相比传统的连接方法有着不可比拟的优势,因此镁合金搅拌摩擦焊已经引起国内外学者的广泛重视。介绍了搅拌摩擦焊的基本原理和接头质量影响因素,详细总结了国内外镁合金搅拌摩擦焊在微观组织、力学性能和塑性流动方面的研究现状,指出了国内外学者已取得的研究成果和不足,点明了焊接接头力学性能的检测标准和材料的真实流动还需进一步地研究与探讨,最后在异种材料的焊接、搅拌头的优化设计和数值模拟等方面对镁合金搅拌摩擦焊的发展前景进行了展望。     

30 mm厚TA1电子束焊接头疲劳断裂原因分析

为探究30 mm板厚TA1电子束焊接头发生疲劳断裂的原因,针对接头开展疲劳试验,获得了接头S-N曲线及条件疲劳极限。针对TA1接头开展宏观、微观组织及力学性能检验,结合对典型低寿命接头的疲劳试样断口分析,获得了接头断裂特征。结果表明:电子束焊接过程使TA1焊缝及热影响区得到强化,整个接头无明显软化区。TA1电子束焊接头S-N曲线数据符合线性拟合规律,其拟合的疲劳极限值163 MPa,为接头抗拉强度的48.7%,接头疲劳强度符合金属材料结构件疲劳设计的一般规律。焊缝内部"微米级"焊接气孔的存在是导致接头发生疲劳断裂的主要原因,部分接头则是因焊接夹渣导致疲劳断裂。     

随焊冲击抑制6061-T6铝合金接头软化行为研究

6061-T6铝合金焊后软化最严重的区域为焊接热影响区,易造成铝合金构件整体强度下降。为了抑制焊接接头的软化现象,通过新参数直流反接TIG焊以及随焊冲击实验对焊接接头进行强化,并通过维氏硬度计、扫描电子显微电镜、能谱分析仪和电化学工作站对冲击试样进行分析。结果发现：随焊冲击后焊接热影响区软化行为减弱,晶界析出的G.P区、Mg2Si、CuAl2以及β相的尺寸和聚集程度变小,晶粒得到细化。焊接热影响区冲击区腐蚀电流小于未冲击区,塔菲尔斜率大于未冲击区,抗腐蚀性能增强。     

Microstructure of the Joint of 1565chM Alloy Sheets Fabricated by Friction Stir Welding

The microstructure in the joints of a non-heat-treatable aluminum–magnesium 1565chM alloy sheets fabricated by friction stir welding is studied. The structure near the interface between the base metal and a welded joint is examined. Friction stir welding results in a gradient structure with ultrafine grains at the center of the welded joint. The structure in the welded joint forms by the mechanism resulting in the formation of a layered ultrafine structure due to plastic deformation by shear and rotation of structural fragments. Layers are assumed to form due to the balance between the strain hardening and the softening caused by frictional heating and heat released during deformation. An analogy between the microstructure in the joint fabricated by friction stir welding and the microstructure formed by sliding friction is drawn.     

镁合金搅拌摩擦焊接技术

对5mm厚镁合金AZ31B板材的摩擦焊接技术进行了试验研究，结果表明：适合其板材的搅拌摩擦焊接的搅拌头，材料为W6MoSCr4V2高速钢，结构为凹面圆台形，根部直径5．5mm，端部直径为2．5mm，轴肩尺寸为12mm，长度为4．7mm。镁合金搅拌摩擦焊接头的抗拉强度可达母材的90％，延伸率可达母材的50％。搅拌摩擦焊接头焊合区为动态再结晶组织，在接头前进边焊合区与母材有明显的分界线，返回边过渡区有金属微熔的迹象。     

深冷处理消除铝合金残余应力的研究

本文介绍了铝合金消除残余应力的深冷处理技术,分析了深冷处理过程的应力状态,给出了残余应力消除的机理是应力反转、晶粒细化和原子间的动能转移。     

Microstructure and mechanical properties of friction stir welding of AZ31B magnesium alloy added with cerium

The AZ31B magnesium alloy sheet added with 0.5 wt.% Ce was welded with friction stir welding(FSW).The microstructures and mechanical properties of the welded joint were investigated.The results showed that the microstructures in the weld nugget zone were uniform and with small equiaxed grains.The grains in the heat-affected zone and the thermo-mechanical affected zone were coarser than those in the base metal zone and the weld nugget zone.The ultimate tensile strength of AZ31B magnesium alloy added with 0.5...     

高导耐热电极合金QCr0．6—0．1的形变热处理工艺研究

含0．5％-1％Cr、0．1％左右zr的铜-铬-锆合金（试验用暂定牌号QCr0．6—0．1）,是著名的电阻焊电极合金,具有导电导热性好、抗软化性高的特点,广泛用于软钢和镀锌钢板的电阻焊领域,其性能取决于该合金生产过程中的形变热处理工艺。在研究了规模化生产条件下,不同形变热处理工艺对材料性能的影响,提出了该合金的形变热处理原则,对规模化生产开发该类具有巨大商业价值的合金品种具有指导意义。     

TIG焊接热循环对AZ31B镁合金硬度的影响

以AZ31B镁合金为研究对象，采用TIG焊方法进行焊接，考察了焊接热循环对镁合金的硬度的影响。测量、比较、分析了焊缝、热影响区、母材的硬度。结果表明，表面处理过程（研磨、抛光、侵蚀液体及工艺等）对镁合金硬度的影响很大，直接影响到“焊接工艺-硬度”之间关系。与母材相比，由于焊缝的冷却速率高，组织细小，硬度较高。热影响区的组织虽比母材粗大，但硬度与母材相近。焊缝区不同部位的硬度存在一定差异。     

Evaluation of Microstructure and Mechanical Property of FSW Welded MB3 Magnesium Alloy

An experiment was carried out on the friction stir welding of MB3 magnesium alloy to determine welding parameters for obtaining an excellent weld appearance without void, cracking, or distortion. Frictional heat and plastic flow created fine and equiaxed grains in the weld nugget, and the elongated and recovered grains in the thermomechanically affected zone （TMAZ）. The grains in the heat affected zone （HAZ） grow slightly. The me- chanical property results show that maximum joint tensile strength can reach 97. 2% of the parent material, which is stronger than that of fusion joints; and the failure almost occurs in the heat affected zone.     

Effect of Deep Cryogenic Treatment on Wear and Corrosion Resistance of an Al–Zn–Mg–Cu Alloy

Russian Journal of Non-Ferrous Metals - The 7075 aluminum alloy was subjected to deep cryogenic treatment (DCT) at –196°C with liquid nitrogen for different hours. The wear and corrosion...     

Formation of Gradient Structures in the Zone of Joining a Deformable Nickel Alloy and a Single-Crystal Intermetallic Alloy during Thermodiffusion Pressure Welding and Subsequent Heat Treatment

The possibility of formation of a high-quality solid-phase joint of an Ni₃Al-based single-crystal intermetallic VKNA-25 blade alloy with a high-temperature deformable EP975 disk alloy by pressure welding is studied to create high-performance one-piece blisk unit for the next-generation aviation gas turbine engines and to decrease the unit mass. The influence of the conditions of thermodiffusion pressure welding under the hightemperature superplasticity of the disk alloy and the influence of heat treatment of welded joints on the gradient structures in the welded joint zone and the structure at the periphery of the welded samples are investigated.