LF2铝合金搅拌摩擦连接研究

对厚度为3mm的LF2铝合金板成功地进行了搅拌摩擦连接．金相组织观察显示焊核区晶粒由原始母材的扁平状转变为更加细小的等轴晶粒，力学性能测试表明热影响区的强度为最薄弱区域．当焊接速度、工具旋转速度、轴向压力分别为60mm／min、1200r／min、400N时，焊缝区的抗拉强度为245 MPa，是母材抗拉强度的92％，延伸率可达到母材的80％以上．     

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by en-ergy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corro-sion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG weld-ing. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints pro-duced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.     

铝／钢CMT焊接工艺参数对界面连接状态及气孔分布的影响

对厚度均为1mm的6061铝合金和浸铝钢板搭接件进行冷金属过渡（CMT）钎焊,研究了工艺参数对焊缝界面连接状态及焊缝气孔数量分布的影响．试验结果表明：随着焊接电流的增加,气孔数量增多,界面连接状态越好;在焊接速度为0．75m／min时,焊缝的气孔量比较少,在满足较好的界面连接状态及焊缝气孔较少的条件下,最后获得焊接电流85A,焊接速度为0．75m／min为最佳工艺．     

预热温度对铝合金搭接激光焊焊缝成形及组织的影响

采用Nd:YAG激光器和1.4 mm厚的5A03H24铝合金板材,在不同预热温度下用相同的激光焊参数进行了搭接激光焊试验。结果表明:焊缝的熔深、熔宽随温度的升高而增大,并在T≥250℃时增大显著;焊缝成形和焊接过程稳定性在T≤250℃时随温度的升高而变好;焊缝组织随温度的升高而粗化,但T≤200℃时粗化不明显;焊缝、热影响区和母材的显微硬度随温度的升高而下降,但T≤100℃时焊缝的显微硬度下降不明显,T≤200℃时热影响区的显微硬度下降不明显,T≤300℃时母材的显微硬度下降不明显。     

Penetration control by weld pool resonance during gas tungsten arc welding

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LF3铝合金焊件尺寸不稳定性研究

试验研究了LF3铝合金焊接件在常温状态下的尺寸不稳定变形规律 ,并对产生这种变形的机理进行了力学和微观组织的分析 .结果表明 :LF3铝合金焊件的焊缝部位在焊后时效过程中发生了沿焊缝纵向伸长的不稳定变形 ,变形发生 6h后试件尺寸趋于稳定 ,试件总相对收缩变形量为 1.0× 10 -5;焊件发生尺寸不稳定变形的原因与微观组织的变化和焊接残余应力的松弛有关 .     

MB2镁合金板搅拌摩擦焊研究

采用不同的搅拌摩擦焊工艺对MB2镁合金进行焊接,并对焊缝的特点,组织形貌及力学性能进行了分析.试验结果表明,对厚为3 mm的MB2镁合金板,当焊接速度为95 mm/min和搅拌头旋转速度为1 600 r/min时,可以获得良好的焊接质量.     

高强钢焊接研究现状及发展趋势

在国家低碳节能发展趋势的推动下,高强钢得到广泛应用,高强钢焊接在交通运输、海洋工程等应用中显得越来越重要.从焊接工艺、焊接接头组织、力学性能等特点对国内外高强钢焊接方面的研究成果进行了综述,得出高强钢焊接接头各个区域的组织与性能不同,在不同焊接规范下相同区域的金相组织基本相似,熔合区因组织不均匀为最薄弱环节,指出防止高强钢热影响区的脆性破坏以及提高钢的韧性是今后高强钢焊接研究的重点.     

单双丝埋弧焊工艺及接头性能比较分析

以生产中常用的16Mn钢材料为焊接母材,采用单丝交流、单丝直流埋弧焊和双丝埋弧焊工艺方法制备焊件.对不同工艺方法得到的焊接接头进行了拉伸试验,焊缝金属和焊接热影响区金属的室温冲击试验,观察了焊缝金属的显微组织,用扫描电子显微镜观察了冲击断口形貌,根据试验数据计算了不同工艺方法下的熔敷速度.比较分析结果表明:双丝埋弧焊工艺下的熔敷速度比单丝交流、单丝直流埋弧焊工艺下的熔敷速度分别提高了108%和64%,焊接速度分别提高了59%和67%,焊接工艺稳定性好,焊缝成形美观.三种工艺方法下得到的焊接接头抗拉强度和屈服强度无明显区别.单丝埋弧焊时焊缝金属的室温冲击韧度值比双丝埋弧焊时的高,单丝交流埋弧焊时焊接热影响区金属的冲击韧度值最高.     

400MPa级超细晶粒钢焊接接头的低温韧性

利用CO2+Ar气体保护焊,分别采用单道焊接和双道焊接工艺对厚度为8 mm的400 MPa级超细晶粒钢钢板进行了焊接,采用系列冲击试验方法对焊接接头的低温韧性进行了研究。试验结果表明,在焊接接头中,焊逢位置低温韧性较差。由于双道焊较小的热输入,减小了焊缝及热影响区组织粗化,其焊接接头的低温韧性好于单道焊,并使热影响区面积变小。     

Microstructure and Properties of an Al 6061/Galvanized Plate Fabricated by CMT Welding

Aluminum alloy 6061 was welded with zinc coated low carbon steel by cold metal transfer (CMT).The microstructure composition,morphology and growth process of the welding joint and the HAZ were researched.The weld area on the side of the galvanized steel sheet mainly contains Fe_2Al_5.And on the side of the aluminum alloy substrate,it is mainly filled with a needle-like FeAl_3.At the same time,Al_8Fe_2Si is formed at the edge of FeAl_3.The zinc-rich region on the side of the aluminum alloy mainly contains an aluminum-zinc solid solution and an aluminum-zinc co-crystal,and the current size had no significant effect on the type and morphology of the compounds produced in the interface layer.     

镁合金双弧焊接过程研究与分析

研究了镁合金MIG-TIG双弧焊接方法,通过工艺实验获得了影响焊接过程的工艺参数(电流、弧长、焊丝末端与钨极末端的间距、焊接速度等)。在总电流为140 A,旁路电流为115 A,电弧电压为21 V,焊丝末端与钨极末端间距为3 mm时获得了成形较为美观的焊缝。分析了工艺参数对焊接过程及焊缝成形的影响,为进一步提高镁合金双弧焊接过程稳定性,获得质量高成形好的焊缝提供了一定的理论基础。     

基于主动形状模型的焊缝定位算法

针对焊接环境对工人造成伤害和焊件材质影响焊接质量的问题,提出了一种应用于机器视觉激光焊缝定位系统的基于主动形状模型的焊缝定位算法.利用支持向量机对焊缝图像局部区域梯度方向信息进行目标图像初定位,运用主动形状模型方法建立特征模型,并计算特征模型和测试样本间马氏距离,从而对形状和姿态参数进行更新得到焊缝坐标.结果表明,基于主动形状模型的焊缝定位算法具有准确性高、抗干扰和误差小的特点,能够满足激光焊缝定位系统对准确性的要求.     

16Mn钢MAG焊接头热影响区尺寸与性能分析

在不同焊接线能量条件下,采用MAG焊工艺在厚度为4mm的16Mn钢母材上进行焊接试验.通过观察焊接接头各区域金属显微组织,测试焊接热影响区尺寸和接头金属显微硬度来研究接头的性能.试验结果表明,随着焊接线能量的增大,焊接接头的热影响区宽度增加.焊接接头过热区金属组织随焊接线能量增加而逐渐粗大,且出现了贝氏体组织,显微硬度...     

Electrochemical corrosion behavior of the laser continuous heat treatment welded joints of 2205 duplex stainless steel

The electrochemical corrosion behaviors of the welded joints of 2205 duplex stainless steel with the laser continuous heat treatment were investigated. The secondary austenite formation is the outcome of thermodynamic equilibrium breach of the alloy during heat treatment and the result of the continuous heat treatment which has the most important effect on the weld material. The partitioning behaviors of chromium and molybdenum as well as the volume fraction of ferrite and austenite have a remarkable influence on the composition of the individual phase. Mechanical examination of the laser trated weld demonstrates that the tensile strength and yield strength increase with increasing the amount of the secondary austenite. It is shown that the ultimate tensile strength of the 6 kW laser-treated weld is higher about 20 MPa than no heat treatment weld and the ductility can be further improved without compromising strength. The results indicate that the welding alters the corrosion behavior because of different post heat treatment power and the broad active peak is not identified which is attributed to the dissolution of the secondary austenitic in the ferrite phase. It is indicated that pitting resistance equivalent (PRE) values of base metal and 6 kW weld are higher than that of other welds; base metal is 33.7, 6 kW weld 33.3, no treatment 32.4, 4 kW weld 32.8, 8 kW weld 32.5. The extent of corrosion resistance improvement after reheating treatment is mainly caused by the removal of nitrogen from ferritic regions, which occurred as a consequence of secondary austenite growth.     

双丝三电弧铝合金熔丝成形性

为了实现双丝三电弧铝合金熔丝的高效化制造,通过进行焊缝形貌分析与力学实验,找出双丝三电弧铝合金熔丝成形的影响因素.结果表明,当增加A3弧电流时,熔深减少,热影响区减小,焊接变形得到改善.阴极清理效果随着送丝速度的增加而增加,但随着A3弧电流的增加而减小.当A3弧电流为35 A时,熔丝质量最佳.当电极端部至工件表面的距离处于9～14 mm之间时,阴极清理效果最佳.相比普通纯Ar保护情况,采用精Ar保护的焊缝表面阴极清理区更宽,焊缝表面也更加干净光亮.     

Comparison of fatigue property between friction stir and TIG welds

The alloy 5052 was welded by friction stir welding （FSW） and tungsten inert gas （TIG） welding. The effect of welding processes （FSW and TIG） on the fatigue properties of 5052 aluminum-welded joints was analyzed based on fatigue testing, and the S-N curve of the joints were established. The results show that the fatigue properties of FSW welded joints are better than those of TIG welded joints. The fatigue strength is determined as 65 MPa under 106 cycling of fatigue life. The microstructure of joints is fine grains and narrow HAZ zone in FSW welds, which inhibit the growth of cracks and produce high fatigue life compared with that of TIG welds. Fracture morphologies also show that the fatigue fracture results from weld defects.     

Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of Friction Stir Welded SSM7075 Aluminium Alloy

7XXX series aluminium alloys generally present low weldability by fusion welding methods because of the sensitivity to weld solidification cracking, vaporization of strengthening alloys and other defects in the fusion zone. Friction stir welding(FSW) can be deployed successfully with aluminium alloys. We presented the effect of post-weld heat treatment(PWHT) on the microstructure and mechanical properties of SSM7075 joints. Semi solid plates were butt-welded by FSW at a rotation speed of 1110 r/min, welding speeds of 70 and 110 mm/min. Solution treatment, artificial aging, and T6(solution treatment and artificial aging combined) were applied to the welded joints, each with three samples. It was found that the T6 joints at the speed of 70 mm/min yielded the highest tensile strength of 459.23 MPa. This condition best enhanced the mechanical properties of FSW SSM7075 aluminium alloy joints.     

搅拌摩擦焊工艺对镁合金焊接接头机械性能的影响

采用不同搅拌摩擦焊工艺焊接镁合金，通过拉伸、三点弯曲试验分析了工艺参数对焊缝机械性能的影响。结果表明，采用合适的搅拌摩擦焊工艺可以成功地焊接镁合金并得到成型美观、质量好的焊接接头，焊缝中因产生充分的塑性流动，弯曲强度高，性能好，在一定参数范围内，随着搅拌头旋转速度R，R/V增加，抗拉强度极限值增加；随着焊接速度V增加，抗拉强度极限值下降，当采用最佳的工艺参数焊接，可得到最大抗拉强度极限值，接近母材的90％。     

锈蚀脚手架钢管轴压稳定性试验研究

为研究锈蚀对扣件式脚手架体系中钢管立杆稳定性的影响,通过对不同锈蚀龄期的钢管进行表面形貌测试,分析锈蚀对钢管内、外壁表面形貌的影响;通过锈蚀钢管材料单调拉伸试验,探讨锈蚀条件下钢材力学性能的退化规律;基于锈蚀钢管的轴心受压试验结果,提出锈蚀钢管立杆稳定性的计算模型。结果表明：随着钢管失重率的增加,钢管表面坑蚀分布由独立蚀坑向溃疡状蚀坑群发展,外壁坑蚀率、算术平均高度和均方根高度均不同程度地高于钢管内壁;锈蚀钢材表面随机分布、大小不一的蚀坑会导致钢材强度与塑性变形能力下降、塑性变形能力劣化更明显;不同锈蚀程度的钢管轴压破坏模式均为整体弯曲失稳,锈蚀钢管的极限荷载随失重率的增加线性下降,峰值荷载对应的轴向位移值逐渐降低。