热镀锌双相钢与普通热镀锌钢点焊工艺对比

用单因素法对比试验了两种基板材料不同的热镀锌钢板的点焊工艺,研究焊接电流、焊接时间和电极压力三个主要工艺参数对点焊质量的影响.结果表明,80 kg级热镀锌双相钢点焊工艺参数比普通热镀锌钢窄很多,普通镀锌钢接头抗拉剪载荷只有双相钢的1/3～1/2;焊接电流和焊接时间对焊点的熔核直径和接头抗拉剪载荷影响很大,电极压力对接头抗拉剪载荷和熔核直径影响甚小,变化幅度仅在500～1 000 N和0.5 mm以内.数据分析表明,以熔核直径为判据优化焊接参数时,抗拉剪载荷波动较大,可能出现强度偏低的情况,为此提出了以抗拉剪载荷为判据进行参数优化的方法,得到0.8 mm厚普通热镀锌钢点焊参数范围:焊接电流10～12.5 kA,焊接时间16～23 cyc,电极压力1 430～3 570 N;1 mm厚80 kg级热镀锌双相钢点焊参数范围:焊接电流10.7～11.7 kA,焊接时间13～19 cyc,电极压力2 150～3 200 N.     

热镀锌高强钢点焊的电极磨损对焊点质量的影响

试验研究了热镀锌高强钢点焊的电极磨损规律,同非镀层低碳钢相比,热镀锌高强钢点焊的电极寿命低、点蚀磨损特征变化明显.在此基础上分析电极磨损对焊点质量影响,电极磨损初期阶段,热镀锌高强钢点焊的飞溅严重、焊点表面产生微裂纹程度大,导致焊点质量下降.最后根据电极磨损对焊点微裂纹与熔核直径影响的试验结果,以微裂纹长度不超过0.25 mm的电极端面电流密度为标准,确定电流递增工艺方案,以减小严重电极磨损对焊点质量的影响.     

DP590GA热镀锌双相钢电阻点焊接头性能

针对热镀锌双相钢板(DP590GA)电阻点焊接头问题,研究了接头正拉和拉剪强度随焊接电流的变化规律,并与普通双相钢板(DP590)点焊接头试验结果进行了比较,同时结合两种钢板点焊熔核尺寸随焊接电流的变化以及SEM能谱分析得出的熔合区锌残留量情况,分析了影响热镀锌钢板点焊接头强度的主要原因.结果表明:当其他焊接参数一定时,DP590GA与DP590点焊接头强度和熔核尺寸随着焊接电流的变化趋势在焊接电流各个阶段有所不同,而熔核区的残留锌量随焊接电流的减小而增加,从而揭示了锌层使点焊区域接触电阻降低和焊接电流密度减小引起的熔核直径减小、熔合区残留锌量增加以及锌层更易引起点焊飞溅三个因素在不同的焊接电流范围内对点焊接头强度的影响作用.     

热镀锌钢板点焊的点蚀对电极使用寿命的影响

热镀锌钢板点焊时电极磨损严重,点蚀特征变化明显.建立点焊过程中的电极端面接触电阻模型与接触热阻模型,分析点蚀变化对电极使用寿命的影响,并进行相应试验验证.结果表明.点蚀的产生与发展使电极端面接触电阻与接触热阻增大,导致电极端面温度升高、电极使用寿命降低.试验研究表明,热镀锌钢板点焊的点蚀区域在高温高压下容易产生微裂纹,镀锌层金属元素沿微裂纹渗八电极的内部,加速了电极失效.     

压焊

热镀锌高强钢点焊的电极磨损机理分析,逆变电阻点焊动态信息的研究,电阻点焊加压机构的动力学模型及仿真,铝管、不锈钢管的高频感应焊接,纯铜与不锈钢扩散焊接头性能及原子扩散动态解析……     

锻压力对双相钢点焊熔核质量的影响分析

由于双相钢电阻点焊过程中的快速冷却,熔核区易形成脆硬马氏体,在进行力学性能评价时会出现焊点界面撕裂等问题.为此,本文以1.4mm双相钢(DP600)为研究对象,研究了点焊过程保压阶段电极锻压力对点焊熔核微观组织和拉剪力的影响.结果表明:增大焊接过程中保压阶段的电极压力,能够显著改善双相钢点焊熔核质量.     

热镀锌钢板连续点焊时电极损耗对焊接质量的影响

镀锌钢板电阻点焊时由于锌层的影响电极损耗非常严重。以厚0.8mm家电用热镀纯锌钢板DX51D+Z为研究对象,探究在正交试验优化焊接参数后,热镀锌钢连续点焊时焊接接头质量变化的规律和电极损耗的特点。结果表明,当采用I=11 kA、P=2 500 N、T=13 cyc的点焊工艺参数组合可获得力学性能最佳的点焊接头;连续点焊试验初期(150点前)焊点力学强度稳定且焊点成形较好,焊接后期(150～300点)接头力学强度波动大,焊接状况不稳定;电极损耗至失效是接头质量急剧下降的主要原因,电极失效形式为头部塑性变形、端面坑蚀和Cu-Zn合金化,在本试验条件下,Cr-Zr-Cu电极焊至150点后显现不稳定现象,电极寿命约280点;失效电极端面的Cu-Zn合金层约65μm。     

压焊

热镀锌高强钢点焊的电极磨损机理分析，逆变电阻点焊动态信息的研究，电阻点焊加压机构的动力学模型及仿真，铝管、不锈钢管的高频感应焊接，纯铜与不锈钢扩散焊接头性能及原子扩散动态解析……     

超高强度钢与镀锌双相钢电阻点焊接头强度试验

试验研究了超高强度硼钢板/镀锌双相钢板的电阻点焊接头质量缺陷及其产生原因,通过正交试验设计,重点讨论了焊接电流、通电时间和电极压力对点焊接头强度的影响.结果表明:超高强度硼钢板/镀锌双相钢点焊中超高强度钢板侧更易出现飞溅和烧穿问题,通电时间和焊接电流强度时点焊接头拉剪强度影响显著,这类钢板组合的焊接应优先采用大电流、短...     

汽车用DP800双相钢点焊工艺窗口和接头性能

开展2.0 mm厚DP800双相钢的电阻点焊试验,测试DP800双相钢点焊工艺窗口,研究焊接电流、焊接时间、电极压力对焊点拉剪力的影响规律,并观察接头不同区域的微观组织。结果表明,DP800高强钢焊接性较好,点焊工艺窗口满足工业应用要求;随着焊接电流和焊接时间的增加,焊点直径和拉剪力先增加后趋于平稳;随着电极压力的增加,点焊直径和拉剪力先增加后减小;焊点热影响晶粒细小,由马氏体组织构成;焊核为典型的柱状晶,显微组织为马氏体和少量的贝氏体。     

Influence of welding current shape on expulsion and weld strength of resistance spot welds

Abstract

The present paper presents the influence of welding current shape on weld strength of resistance spot welds of zinc coated mild steel sheets. The influence is analysed at different levels of the electrode wear. Welding currents with different peak values and different RMS (root mean square) values were used in the experiment. The results show that welding current with high peak values implies higher weld strength.     

Effect of variable electrode force on weld quality in resistance spot welding

Abstract

Resistance spot weldability is defined as the acceptable welding current ranges as determined by the weld lobe in resistance spot welding. Nowadays many studies have focused on the effect of welding current and welding time under constant electrode force on the weld quality and weldability. There is little research on the influence of variable electrode force on the weld quality and weldability because of the difficulty in controlling variable electrode force using pneumatic gun. In the present study, first, the influence of three stages of electrode force, including squeeze force, welding force and forging force, on the quality of welds is analysed. Then a design of experiment approach is applied to analyse the influence of the three stages of electrode force on welding quality and thus to obtain optimum parameter of variable electrode force by controlling the electrode force with servo gun. The comparisons of tensile shear strength, nugget size, weld lobe width and wear rate of electrode tip between variable force and constant force are carried out. The results show that the weld quality and weldability can be increased evidently using optimum parameter of variable electrode force without accelerating the electrode wear rate.     

600MPa级高Al冷轧双相钢的点焊工艺研究

基于600 MPa级高Al冷轧双相钢WHT600DP的点焊工艺和力学性能试验,以及接头的宏观金相分析,研究了焊接电流、焊接时间等工艺参数变化对点焊接头压痕深度、焊核直径、焊透率以及拉剪强度等性能指标的影响规律,进而得到了WHT600DP钢的焊接工艺窗口图.研究结果表明:在焊接时间变化较大的情况下,WHT600DP钢的可...     

Improvement of resistance spot weldability for dual-phase (DP600) steels using servo gun

Dual-phase (DP) steel is a kind of advanced high-strength steels (AHSS) developed specifically for automotive application due to its excellent formability and better crash absorption than other conventional AHSS. Resistance spot welding (RSW) is the dominant sheet metal joining method in automobile industry, whereas the weldability of dual-phase steel using conventional air gun is not so excellent for the weld lobe diagram under constant electrode force is too narrow. However, this disadvantage can be easily overcome by servo gun's electrode force control function. This paper mainly relates how to improve weldability of dual-phase steel by adjusting electrode force during spot welding process. By modifying the electrode force using an orthogonal experimental design method, the result shows that the width of weld lobe diagram of dual-phase steel can be nearly doubled.     

Study of resistance spot weldability of a new stainless steel

ABSTRACT

The weldability of a newly developed stainless steel was investigated by comparing with hot-dipped galvanised dual phase and low carbon steels in a two-sheet stack-up of similar metal. The weld lobes, mechanical properties, weld morphology, microstructures and microhardness profiles of the welds made with the three materials were comparatively discussed. Results showed that significant softening was observed in the stainless steel weld nugget. Compared to the dual phase steel and low carbon steel, the stainless steel has a very narrow weld lobe but requires lower welding current and shorter welding time, and the stainless steel weld performed better mechanical properties in the case of welds with same nugget size, but it tended to exhibit interfacial fracture in tensile shear tests.     

镀镍钢板和镍板微型点焊时电极粘附机理的研究

研究了镀镍钢板和镍板微型点焊时电极粘附的机理以及焊接电流、焊接时间、电极压力和电极间距对电极粘附力的影响规律。结果表明；镀镍钢板和镍板微型点焊时电极粘附的机理是电极和镀镍板之间的局部焊接，电极粘附力随电极与镀镍板之间局部焊接面积的增加而增加；电极粘附力随点焊电流和点焊时间的减小而下降。此外，电极压力和电极间距对电极粘附力也有一定的影响。     

Microstructural characterisation of double pulse resistance spot welded advanced high strength steel

The effects of single and double pulse resistance spot welding on the microstructures of an advanced high strength automotive steel are presented in this work. The double pulse welding schemes partially remelt the primary weld nugget and anneal the area at the fusion boundary of the nugget. The effects of the annealing treatment on the segregation and the microstructure have been studied by electron probe microanalysis (EPMA) in combination with electron backscatter diffraction (EBSD). Results show that phosphorus has been redistributed at the primary weld nugget edge of the double pulse welds, while the mean block width and ellipticity of the prior austenite grains were smaller in welds subjected to double pulsing compared with single pulse weld. A favourable failure mode was obtained for the double pulse welds although behaviour did not correlate with the measured grain size.     

PH1500热成形钢电阻点焊焊接性能研究

研究PH1500热成形钢的电阻点焊焊接特性,探讨该工艺下钢板的焊接电流窗口、焊点的微观组织、显微硬度和力学性能等方面的特点,分析其焊接特性。结果表明,1.2 mm厚的该钢种焊接窗口为1.6 kA,最小和最大焊接电流分别为7.2 kA和8.8 kA。在最小和最大焊接电流下,焊点的热影响区都存在软化点。最小焊接电流下焊点焊缝的硬度值波动较小,焊缝硬度略高于最大焊接电流下焊点焊缝的硬度值。相对来说,焊接电流对抗剪力的影响较小,对抗拉力的影响较大。