不等厚2219铝合金板回填式搅拌摩擦点焊接头组织及性能研究

针对航空航天技术需求,采用回填式搅拌摩擦点焊技术对不等厚(2mm+8mm)2219铝合金板进行了焊接。通过改变焊接工艺参数(旋转速度、焊接时间和下压量),分析了不同焊接参数对点焊接头宏、微观组织及力学性能的影响规律。结果表明,随着旋转速度的增加,点焊接头拉剪力先增加,后降低;而延长焊接时间,可以提高接头拉剪力,但过长的时间会导致接头拉剪力降低;焊接下压量的选择,既要保证上下板的结合,又不能导致下板过度软化。当旋转速度为1 800r/min,焊接时间为6s,下压量为2.6mm时,所获点焊接头的拉剪力最大,为7 924N。回填式搅拌摩擦点焊接头有三种断裂型式:塞型断裂、剪切断裂和塞型-剪切混合型断裂。其中,发生塞型-剪切混合型断裂时,点焊接头的拉剪力较大。     

TRIP980高强钢/SPCC低碳钢的异种钢电阻点焊工艺优化及接头性能分析

以厚度均为1.5 mm的TRIP980高强钢/SPCC低碳钢的异种钢板电阻点焊接头为研究对象,以接头剪切拉伸载荷为评价指标,运用正交试验优化其焊接参数,采用极差法和方差法对结果进行分析,随后增加焊前预热条件,分析对比相同焊接电流、焊接时间、电极压力参数下采用预热和无预热时点焊接头的剪切拉伸载荷,利用电子拉伸试验机、金相显微镜和显微硬度仪分别对预热和无预热两种条件下较优焊接参数时的点焊接头性能及显微组织进行测试和分析,研究TRIP980高强钢/SPCC低碳钢的异种钢板电阻点焊接头力学性能及接头各区域的金相组织、硬度特点。结果表明:运用焊前预热能够获得性能良好的点焊接头,相同焊接参数情况下,预热点焊接头的剪切拉伸载荷比无预热高5.5%以上;两种条件下较优焊接参数时,无预热点焊接头为脆性断裂,预热点焊接头为韧-脆混合断裂;采用预热获得的点焊接头组织比无预热更为致密;预热点焊接头熔核和母材的硬度比无预热时有所下降,熔合线硬度过渡平缓。其主要机理是,预热使点焊接头熔核周边优先发热,热影响区扩大,熔核韧性提高和熔核周边应力集中缓解,从而提高了点焊接头的强度。     

DP780双相钢电阻点焊接头的显微组织和力学性能

通过电阻点焊对2.0mm厚DP780双相钢板进行焊接,通过接头的焊接质量检验得到了较佳的焊接参数,并研究了接头的显微组织、剪切力和显微硬度。结果表明:较佳的点焊工艺参数为焊接压力5kN,焊接电流9~10.5kA,焊接时间320~400ms;在较佳的焊接工艺下,点焊接头的熔合区主要为马氏体,热影响区主要由尺寸较小的马氏体、铁素体和贝氏体组成;当焊接电流为9.5kA、焊接时间为400ms、焊接压力为5kN时,点焊接头的剪切力和熔核直径均达到最大,分别为32.58kN和7.9mm;在相同的点焊时间和压力下,随着焊接电流增大,熔核区的显微硬度降低。     

工艺参数对QStE460TM酸洗钢电阻点焊接头性能的影响

随着轻量化在车身制造中的应用,新材料焊接性能的研究至关重要。通过一系列焊接实验获取不同焊接工艺参数条件下QStE460TM酸洗钢电阻点焊接头,同时对接头的几何形貌、显微硬度和准静态力学性能进行对比分析,结果表明:随着点焊电流的增大,QStE460TM酸洗钢的熔核直径和接头准静态强度增大,而熔核区的显微硬度下降;随着焊接时间的增加,QStE460TM酸洗钢的熔核直径先增大后趋于稳定,熔核区显微硬度和接头准静态强度呈现先增大后降低的特点。     

铝合金摩擦点焊工艺参数的优化

摩擦点焊是在搅拌摩擦焊基础上开发的1种新型固态连接技术.针对2 mm厚的LY12铝合金,采用正交试验设计方法对点焊工艺参数进行了优化.试验结果表明,搅拌头形状对焊点剪切强度的影响最显著,其次是焊接时间,搅拌头轴肩直径的影响最小.优化后的最佳工艺参数为：搅拌头旋转速度为2 500 r/min,焊接时间为12 s,轴肩直径为16 mm,搅拌头为探针带左螺纹圆柱形搅拌头.采用优化后的最佳工艺参数进行焊接,焊点的剪切强度达为9.24 kN,比优化前焊点最佳剪切强度提高了5.06%,是电阻点焊焊点剪切强度的1.5倍,是铆接接头剪切强度的2.5倍.     

基于不同焊接条件下接头组织和断裂韧度分析

研究不同焊接条件下的接头组织以及其断裂的韧度。介绍振动焊接工艺的工作原理，并进行对比试验，然后对试验结果进行分析，分析的内容包括金相分析、断裂韧度试验分析。不同的焊接方式，其接头组织以及断裂韧度的试验结果都存在一定的差别。基于不同焊接条件下接头组织和断裂韧度具有差异。     

T91钢焊接工艺研究及应用

对T91钢材料性能和焊接性分析表明T91钢淬硬倾向大,对氢致裂纹非常敏感,焊接过程极易出现氢裂纹,预防措施不当可造成部件断裂,但通过选择适宜的工艺参数、制定合理的焊接工艺可以有效地预防缺陷的产生。对Φ42×6的T91钢管对接接头进行了焊接工艺评定,在选定的工艺参数条件下,焊接工艺性能良好;经无损检测合格后,对熔敷金属进行了化学分析,并对接头进行了力学性能试验和金相试验,结果显示各项技术指标均满足相关标准的要求。工艺试验和实践均表明,合理的焊接工艺加有效的预防措施完全可以预防T91钢焊接缺陷的产生,获得优良的焊接接头。     

基于响应曲面法的点焊工艺参数设计

采用响应曲面法(RSM)对ST14进行点焊工艺实验设计,并通过优化焊接参数来提高接头的抗剪强度。建立接头抗剪强度与焊接参数之间的二阶数学模型,并通过验证试验检验所建立的数学模型的准确性,可以被用于后续的优化分析。根据优化方案得到最佳工艺参数:焊接电流为12.21kA,焊接时间为200ms,焊接压力为0.58 MPa。     

焊接电流对不等厚异质高强钢点焊接头组织性能的影响

采用电阻点焊工艺将热处理后1.8mm的22MnB5钢与1.5mm的TRIP590钢实施了焊接处理,并且对点焊后的22MnB5/TRIP590不等厚异质高强钢的点焊试样分别做以拉剪试验、显微硬度测试以及显微组织的观察,分析了焊接电流这一焊接工艺参数对于点焊接头显微组织以及力学性能的影响。     

铝镁合金填充式搅拌摩擦点焊接头的显微组织及力学性能

对2.0mm厚的5A06铝合金板进行不同工艺参数的填充式搅拌摩擦点焊,并对点焊接头进行了显微组织观察及剪切拉伸、十字拉伸试验。结果表明:接头可以分为焊核区、热机影响区、热影响区、压力影响区和母材区等部分,其显微组织主要为α-Al固溶体,并有金属间化合物β-Mg2Al3相等在基体上分布;随着焊接时间延长和焊接旋转速度的增大,点焊接头的剪切拉伸性能和十字拉伸性能呈现先快速增加后缓慢下降的趋势;当焊接旋转速度为2 000r·min-1,焊接时间为3.5s时,点焊接头最大剪切拉伸载荷可达8 194N,最大十字拉伸载荷可达3 565N。     

AZ31镁合金TIG氩弧焊接应力场的数值模拟

以开V形坡口镁合金薄板对接为例,利用ANSYS软件对其焊接过程进行了模拟分析。首先建立了一个三维有限元模型,并利用生死单元技术模拟实际的焊接过程,得到了焊接温度场及残余应力场的分布情况,并对结果进行了分析和讨论。同时,在相同工艺条件下完成了实际的焊接实验,并对焊接残余应力进行了测量。实测结果与计算结果比较吻合,这说明ANSYS的单元生死技术可以有效地模拟焊接过程,本方法对焊接模拟工作中各种关键问题的处理比较得当。     

2A12铝合金板焊接裂纹分析

研究了CZ状态的铝合金板在退火时退火工艺对机械性能和原始组织的影响,继而对焊接性能产生影响,以及焊接的连接方式对铝合金焊接性能的影响,分析了2A12铝合金板材在焊接时出现裂纹的原因,并提出了解决方法.     

10kW级光纤激光厚板焊接表面塌陷的试验研究

针对12mm厚的SUS 304不锈钢板的大功率光纤激光焊接过程中,焊缝表面容易出现塌陷的问题,利用高速相机及“三明治”焊接方法拍摄了熔池的流动状况。讨论了焊接位置和焊接速度以及底部驼峰的形成对表面塌陷的影响,研究了塌陷产生的原因。结果表明:从水平焊接位置到竖直焊接位置的过程中,表面塌陷平均深度逐步减小。焊接速度越小,小孔前沿孔壁上“凸台”越大,表面塌陷越严重。底部驼峰的形成,导致熔池熔融金属不足,形成表面塌陷。     

Inertia friction welding process analysis and mechanical properties evaluation of large rotor shaft in marine turbo charger

The two aims of this study are first, determining the optimal welding process parameters by using the finite element simulation and second, determining the optimal tempering temperature by evaluating the mechanical properties of friction welded part for manufacturing large rotor shaft. Inertia welding was conducted in order to make the large rotor shaft of turbo charger for low speed marine diesel engine. The rotor shaft is composed of the 310mm diameter disk and the 140mm diameter shaft. Since diameters of disk and shaft are very different, the integration using friction welding reduces manufacturing cost compared with the forming process of which a disk and shaft are forged into one body. Finite element simulation was performed, because inertial welding friction process depended on many process parameters, including axial force, initial revolution speed and energy, amount of upset, and working time. It is expected that this modeling will significantly reduce the number of experimental trials needed when determining the optimal welding parameters. Inertia welding was carried out with optimal process parameter conditions obtained from the simulation results. Welded joint part, made by friction welding, had very poor mechanical properties, and so it required heat treatment. The base material used in the investigation was SFCMV1 (SANYO special steel, high strength low alloy Cr-Mo steel) of 140mm diameter. In the study, heat treatment test carried out quenching (950 °C, 4hr, oil cooling) and tempering (690–720 °C, 6hr, air cooling) for friction welding specimens. The various tests, including microstructure observation, tensile, hardness, and fatigue tests, were conducted to evaluate the mechanical properties under various heat treatment conditions after inertia welding.     

A study on fiber laser micro-spot welding of thin stainless steel using response surface methodology and simulated annealing approach

This study analyzed variations of shear strength that depend on the fiber laser process during micro-spot welding of AISI 304 stainless thin sheets. A preliminary study used ANSYS results to obtain initial process conditions. The experimental plan was based on a Taguchi orthogonal array table. A hybrid method that includes the response surface methodology (RSM)- and back propagation neural network (BPNN)- integrated simulated annealing algorithm (SAA) is proposed to search for an optimal parameter setting of the micro-spot welding process. In addition, an analysis of variance was implemented to identify significant factors influencing the micro-spot welding process parameters, which was also used to compare the results of BPNN-integrated SAA with the RSM approach. The results show that the RSM and BPNN/SAA methods are both effective tools for the optimization of micro-spot welding process parameters. A confirmation experiment was also conducted in order to validate the optimal welding process parameter values.     

00Cr26Mo1超纯高铬铁素体不锈钢的焊接技术研究

介绍在高温、高腐蚀性介质中工作的00Cr26Mo1超纯铁素体不锈钢材料性能及其焊接技术要求。防止焊接接头脆化和晶间腐蚀是焊接技术的关键,在焊接试验基础上,制定合理的产品现场焊接工艺,包括焊接材料的选择、焊接规范参数和焊接技术措施。实践证明,通过严格加强焊接全过程保护,防止焊接过程污染,能够获得优良的焊接质量。     

Process modeling and parameter optimization using neural network and genetic algorithms for aluminum laser welding automation

In the automotive industry, applying aluminum alloys to car chassis have become an important concern in order to reduce car weight. In aluminum laser welding, the strength of weld is typically reduced by porosity, underfill, and magnesium loss. In order to overcome these problems, laser welded with filler wire was suggested. In this study, experiments on the laser welding AA5182 of aluminum alloy with AA5356 filler wire were performed with respect to laser power, welding speed, and wire feed rate. The experiments showed that the tensile strength of the weld was higher than that of the base material under certain conditions. Using the experimental results, a neural network model was proposed to predict the tensile strength. To optimize the process parameters, a fitness function was formulated, taking into account weldability and productivity. A genetic algorithm was used to optimize the laser power, welding speed, and wire feed rate. The optimal value of these parameters was considered to be the proper process conditions in terms of weldability and productivity.     

阀体焊接机器人运动性能分析

基于弗莱那-雪列（Frenet-Serret）矢量理论,获得了离散焊点处的切向、法向和次法向矢量,据此可求得焊枪-焊点间的相对位姿。基于变位机-机器人主从运动链末端的耦合约束关系,提出以船型焊为最佳焊位时的协同焊接运动学模型及参数求解流程。在求解焊接机器人工作空间的基础上,依据球形手腕六关节串联机器人处于奇异位形的几何条件,归纳得出焊接机器人的10种独立的奇异位形。协同焊接阀体密封面的运动仿真和现场试验表明,该变位机-机器人焊接系统能够平稳、准确地完成预期焊接任务,证实了提出的协同焊接运动学模型及参数求解方法正确可行。     

An application of genetic algorithm for edge detection of molten pool in fixed pipe welding

This paper presents a study on an application of genetic algorithm (GA) for edge detection of molten pool in fixed pipe welding. As circumferential butt-welded pipes are frequently used in power stations, offshore structures, and process industries, it is important to investigate the characteristic of the welding process. In pipe welding using constant arc current and welding speed, the bead width becomes wider as the circumferential welding of small-diameter pipes progresses. In order to avoid the errors and to maintain the uniform weld bead over the entire circumference of the pipe, the welding conditions should be controlled as the welding proceeds. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position using the AC welding machine. The monitoring system used an omnidirectional camera to monitor backside image of molten pool. A method of optimization for image processing algorithm using GA was proposed and has been implemented into a process to recognize the edge of molten pool. The result of detection, which is back bead width, was delivered into a fuzzy inference system to control welding speed. The experimental results show the effectiveness of the control system that is confirmed by a sound weld of the experimental results.     

Analysis of characteristics of molten pool using cast shadow during high-power disk laser welding

On-line monitoring and control of laser welding process play an important role in welding quality assessment. The morphology of molten pool during welding process influences welding quality. Volume, tilt, and height were characteristics of molten pool, but they cannot be measured directly during the welding process. An experiment of surfacing weld of Type 304 austenitic stainless steel with high-power disk laser welding was implemented. An active vision system with an auxiliary laser light source was designed to acquire the images of molten pool and its shadow during the welding process. The images were pre-processed to analyze the characteristics of the casting shadow of molten pool instead of analyzing the characteristics of the molten pool itself. The area, maximal distance between the shadow and keyhole, maximal width, and the tilt of the shadow were selected as the characteristics to analyze the relationship between the morphology of molten pool and welding quality by linear and 10th non-linear fitting. The results indicated that the welding quality could be dynamically detected by observing these characteristics. A different welding process was also conducted to confirm the proposed method. The research in this paper provides a method for on-line monitoring and control during high-power disk laser welding.