钛合金窄间隙激光填丝焊接工艺及接头组织性能分析

采用自主研发的Ti-Al-V-Mo系钛合金药芯焊丝为填充金属,进行TC4钛合金板窄间隙激光填丝焊接工艺实验,研究激光功率、摆动参数、焊接速度和送丝速度等工艺参数对焊缝成形的影响规律;借助高速摄像系统研究焊接过程羽辉及等离子体特性,并对获得的焊接接头组织性能进行分析。研究结果表明：采用激光功率4.0 kW、圆形摆动模式、摆动频率100 Hz、摆幅2 mm、焊接速度0.42 m/min、送丝速度0.6 m/min的工艺参数组合下得到的焊缝成形良好,无明显外观缺陷;当焊丝末端与液态熔池接触距离为0 mm时,过渡方式为液桥过渡,可以实现焊丝熔化金属向熔池的稳定、有序过渡;该焊接工艺获得的20 mm厚TC4钛合金板窄间隙激光填丝焊接头组织性能良好。     

单束与双束串行激光填丝焊特性对比

以铝合金为研究对象,研究了双束串行激光填丝焊不同能量比对焊缝成形及焊缝气孔率的影响,并与单束激光填丝焊工艺进行对比。进一步借助高速摄像机对双束串行激光填丝焊能量比R为20/80以及单束激光填丝焊的熔池、匙孔以及等离子体的变化进行对比分析,获得了双束串行激光填丝焊能量比R为20/80时焊缝气孔率降低的原因。结果表明,对于双束串行激光填丝焊,当能量比R为20/80时焊缝气孔率较低。与单束激光填丝焊相比,双束激光填丝焊能量比R为20/80的焊缝气孔率降低了38%,而且焊接过程中焊丝熔化后沿熔池边缘流入,可大幅降低对匙孔的冲击作用,匙孔始终处于张开状态,焊接过程中等离子体的形态波动相对较小,表明焊接过程的稳定性较好。     

5A90铝锂合金激光焊搭接接头的组织和性能

以厚度为3.0和4.0 mm的5A90铝锂合金板为研究对象,系统地开展了铝锂合金双光点激光焊接工艺研究,并对激光焊搭接接头的组织和性能进行了分析。结果表明:通过合理的选择激光功率和焊接速度可保证焊接过程的稳定性,改善焊缝的成形质量;在母材半熔化区与焊缝柱状晶之间存在一条等轴细晶带,焊缝中心组织为等轴树枝晶,晶粒尺寸一般随激光功率的降低和焊接速度的增大而细化和均匀化。     

FV520B钢激光焊接工艺参数优化及组织性能

借助正交试验方法优化FV520B钢板激光自熔焊焊接参数,以便为后续开槽焊叶轮的激光打底焊提供参数选择依据.利用极差分析法进行焊接参数初选,以熔深为响应量,在较大的参数范围内选出符合熔深条件的较小参数范围.经参数复选,确定的优化焊接参数为:激光功率4.2 kW,焊接速度35 mm/s,光斑直径1.2 mm.选用优化参数进行对接自熔焊,观察发现焊缝熔化区(FZ)组织主要为白色的马氏体和黑色的δ铁素体,并含有少量的碳化物,其中δ铁素体呈现出蠕虫状和板条状两种形态.激光线密度对焊缝熔深的影响较大,熔深随线密度的增大而增加,呈幂函数关系;焊缝的维氏硬度随线密度的增大而略有降低.优化参数后经对接焊得到的焊缝熔化区的硬度略低于母材(BM),热影响区(HAZ)软化比较明显.拉伸实验结果表明,由于缺陷的存在,焊缝的屈服强度、抗拉强度低于母材;而无缺陷或者极少缺陷的情况下,焊缝的强度优于母材.     

激光熔丝增材过程传热流动行为数值模拟

目的 研究激光熔丝增材制造过程的熔池流动特性,探究工艺参数对熔池流动与传热行为的影响.方法 建立了考虑运动丝材持续送进过程的激光熔丝增材熔池传热和流动行为数学模型.针对316L不锈钢的激光熔丝增材制造,开展了成形过程中丝材送进、熔化和凝固行为的实验和数值模拟研究.结果 模拟结果 显示在成形过程中,准稳态阶段激光辐照中心的最高温度约为2500 K.金属液主要由丝材端部向熔池尾部流去,并在熔池尾部凝固形成堆积体.同时,熔池表面最大速度可达0.8 m/s,并具有速度振荡特征.结论 基于激光熔丝增材制造过程数学模型的模拟结果 与实验吻合良好,结果 表明,减小送丝速度会增大熔池表面高温区面积,并导致熔池的速度振荡程度增加.     

焊接参数对铝合金激光填丝焊缝成形的影响

采用ER5356焊丝对1.2mm厚5A06铝合金和3mm厚5A90铝锂合金进行激光填丝焊接实验,探讨了焊接参数包括光丝间距、送丝速率、激光功率和焊接速率等对焊缝成形的影响.结果表明:光丝间距必须控制在一定范围内才能获得成形较好的焊缝,且其优化范围受焊接速率的影响显著;母材板厚较小有利于激光填丝焊优化送丝速率的提高及其范围的扩大;焊接速率对焊缝成形的影响较大,随着焊接速率的增加,激光功率应随之增加与其匹配;激光填丝焊时在保证熔透性且较好成形的基础上,应尽量采用较小的焊接热输入.     

熔池形态对铝-铜激光焊接头组织和性能的影响

对T2紫铜板、2A16铝合金板进行激光熔化焊和熔钎焊试验,分析接头的力学性能,并研究其微观组织及界面形貌,阐述熔池形态对接头组织和性能的影响.结果表明:采用激光熔化焊时得到熔化焊熔池,当焊接线能量Q=1160 J/cm时,其界面层由Al4 Cu9+Al2 Cu化合物和(α-Al)+(θ-Al2 Cu)共晶组织组成,总厚度为60.9μm.采用激光熔钎焊时得到熔钎焊熔池,当Q=1466.67 J/cm时,接头抗拉强度为274.25 MPa,相比熔化焊接头提高了280.9％,其界面层由CuZn5和Al2 Cu化合物组成,总厚度为10.23μm.接头接触界面的互扩散系数(D熔化焊>D熔钎焊)和不同熔池形态下的环形对流共同影响了IMC层厚度,从而决定了接头的性能.     

激光功率对钛合金双侧同步焊接温度场的影响

为研究激光功率对TC4钛合金T型结构双激光束双侧同步焊接温度场的影响,针对TC4钛合金T型结构的双激光束双侧同步焊接过程,建立了相应的有限元模型,利用有限元分析软件进行了焊接过程温度场的计算,研究了激光功率对熔池形状的影响规律,并对不同激光功率下的温度场进行了分析。结果表明:随着激光功率的增加,熔池的熔深、熔宽均有所增加,且在焊接过程中熔池的升温速率与降温速率明显升高。同时,激光功率对熔池区域的温度分布影响更为显著,熔池前端的温度梯度随激光功率的增加而增大,且熔池上表面熔化面积也有所增加。本文得出的仿真结果可为后续钛合金蒙皮-桁条T型结构双激光束双侧同步焊接提供工艺指导。     

超薄铝合金胶粘接及激光焊接工艺研究

目的 为了解决厚度为0.05 mm的铝合金在激光焊接过程中,材料发生变形导致的焊穿或者虚焊问题.方法 采用在下层铝合金材料表面均匀涂覆粘胶剂,将上下2层铝合金材料进行预固定,然后采用激光焊接,形成焊缝.通过控制涂覆粘胶剂的次数,得到胶层厚度为11.2μm,对涂覆粘胶剂的铝合金进行激光焊接实验.结果 当激光平均功率为150 W,焊接速度为100 mm/s,离焦量为2 mm时,焊缝剪切强度最大,为124 MPa,达到母材剪切强度的82％.结论 通过粘胶剂预固定后,在激光加热过程中,可以很好地克服材料的变形,让上下材料形成熔池,熔池冷却凝固后熔合在一起形成焊缝,可以解决材料发生变形导致的焊穿或者虚焊问题.     

铝合金方波交流等离子弧立焊穿孔熔池动态稳定性研究

采用工频方波交流电源和相应自制设备研究了焊接工艺参数对穿孔熔池动态稳定性的影响规律。结果表明:间隙对穿孔熔池动态稳定存在影响较大。焊接电流一定范围内变化对穿孔熔池动态稳定性影响较小。虽然离子气流量的变化对穿孔熔池的孔径影响较小,但对熔池金属的流动性和焊缝成形影响较大。正确送丝可提高穿孔熔池动态稳定性。上述规律为铝台金方波交流等离子弧立焊过程焊接质量控制提供了依据。     

A Novel Method of Triple-Wire Gas Indirect Arc Welding

This paper proposes a novel triple-wire gas indirect arc welding process. The welding system consists of two power sources and three wires. The effects of the power source mode and the wire configuration on arc stability and behavior are studied. The metal transfer is analyzed and bead-on-plate welding is employed. Results show that two direct current power sources cannot produce a stable process, but the combination of a direct current with a pulsed direct current can produce a stable process. The reason is that the pulsed direct current can boost and stabilize the metal transfer. For the wire configuration, a smaller contact angle between the main wire and the side wire is more desirable. Compared with the traditional gas metal arc welding, this novel process has the advantages of high wire melting rate, low penetration depth, and low dilution rate. Compared with twin-wire gas indirect arc welding, it provides a broader range of applicable currents with sufficient heat input.     

Experimental investigation on the effects of process parameters of GMAW and transient thermal analysis of AISI321 steel

Gas metal arc welding (GMAW) develops an arc by controlling the metal from the wire rod and the input process parameters. The deposited metal forms a weld bead and themechanical properties depend upon the quality of the weld bead. Proper control of the process parameters which affect the bead geometry, the microstructures of the weldments and the mechanical properties like hardness, is necessary. This experimental study aims at developing mathematical models for bead height (HB), bead width (WB) and bead penetration (PB) and investigating the effects of four process parameters
viz: welding voltage, welding speed, wire feed rate and gas flow rate on bead geometry, hardness and microstructure of AISI321 steel with 10 mm thickness. The transient thermal analysis shows temperature and residual stress distributions at different conduction and convection conditions.     

Rapid prototyping with high power fiber lasers

Laser rapid prototyping technologies comprise a set of technologies used in a wide range of materials to produce prototypes or small batches of complex shaped components. This paper presents a research work on rapid prototyping technology with laser additive manufacture of wire based alloy Ti-6Al-4V with an 8 kW fiber laser for the production of components with cylindrical geometry. For this, an engineering system was developed, a demonstration part produced and the deposition process was characterized. Two processing parameters were investigated: and these were the relative position between the wire feeding system and the substrate and the laser beam to wire width ratio. The former affects the molten metal transfer mode and the pressure exerted by the wire tip on the molten pool, while the laser beam to wire width ratio affects the process efficiency, since this is a compromise of process stability and process speed. Both parameters control surface finishing and the smoothness of the part. The melting efficiency of the process is low when compared to alternative processes involving powder pre deposition, but the density of the part is improved with homogeneous structural characteristics.     

TIG电弧热丝对铜、钢堆焊的工艺研究

针对某产品铜带焊接工艺,提出了一种电弧热丝方式应用于TIG堆焊铜、钢工艺的研究。电弧热丝可有效预热低电阻率的焊接材料,如铜;传统的电阻热丝只能加热具有高电阻率的焊接材料,如钢。采用电弧热丝系统,热丝电流小于50A时即可有效预热焊丝,与电阻热丝电流400A相当。在相同焊接电流下,能够大大提高焊接熔敷速度;在相同送丝速度下,降低焊接电流,大大降低焊接设备功率。同时证明2种热丝加热方式对钢基体、铜合金的影响相同,特别是对堆焊层铜合金中泛铁量的影响相当。     

芯片封装中铜丝键合技术的研究进展

铜线具有优良的机械、电、热性能,用其代替金线可以缩小焊接间距、提高芯片频率和可靠性.介绍了引线键合工艺的概念、基本形式和工艺参数;针对铜丝易氧化的特性指出,焊接时必须采用特殊的防氧化工艺,以改善其焊接性能;最后对铜丝键合可靠性及主要失效模式进行了分析.     

变极性等离子弧穿孔熔池受力及焊缝成形稳定性

通过YB005-01型压力变送器测定相同参数条件下正极性等离子电弧力大于反极性等离子电弧力,并建立了铝合金VPPA焊接穿孔熔池受力模型,分析了在不对称正、反极性等离子电弧力的作用下,穿孔溶池稳定性及其焊缝成形机理.同时进一步分析铝合金VPPA力学特性,掌握了焊接电流和离子气流量等重要焊接参数对其影响.经穿孔焊工艺实验,...     

Optimization of Processing Parameters During Laser Cladding of ZE41A-T5 Magnesium Alloy Castings Using Taguchi Method

A continuous wave 4 kW Nd:YAG laser welding system was employed to clad single beads on machined 6.2-mm thick ZE41A-T5 aerospace magnesium alloy sand castings using nominal 1.6-mm filler rods of the parent metal. Based on the quality criterion of minimum dilution ratio, the Taguchi experimental method was used to optimize different process parameters and to identify the dominating factors. It was found that, for the process window investigated in this work, the optimal levels were 5.0 m/min for wire feed rate, 2.25 kW for laser power, and 2.5 m/min for cladding speed, with a minimum dilution ratio of 0.155. With 95% confidence, the wire feed rate is the dominating factor with the most significant influence on the dilution ratio. The dilution ratio usually decreases with increased wire feed rate while it increases with increased laser power. By contrast, the cladding speed appears to have insignificant influence on the dilution ratio over the cladding speed range used in this study.     

Investigation on Cracking in the Surfacing Welding Layer of Ni_3Al Based Alloy

Investigation has been made into the causes of cracking in the Surfacing welding layer of Ni3Al based alloy by analysing both the liqu id-to-solid transformation in the molten pool and the distribution of thermal stress within the surfacing welding layer. The results show that cracking in the surfacing welding layer is directly related to the producing of eutectic phase β' (NiAl) in the interdendritic region and high thermal stress within the surfacing welding layer. When the process of electric arc surfacing welding is changed from along straight line to along" Z" pattern, cracking in the surfacing welding layer of Ni3Al based alloy is prevented due to being reduced of both the cooling rate of liquid in the molten pool and the moving speed of the heat source. Reducing the melting volume of the substrate material by lowering the output power of electric arc welding would make the content of iron atoms in the molten pool decrease. and this also can reduce the trend of the eutectic reaction in the interdendfitic region and is helpful to Suppress cracking in the surfacing welding layer.