共查询到19条相似文献,搜索用时 265 毫秒
1.
高强钢和铝合金的连接在汽车轻量化中具有重要的研究价值。针对DP590高强双相钢和6061铝合金分别采用交流和中频逆变点焊机进行电阻点焊试验,研究不同点焊工艺参数对钢一铝熔核尺寸、点焊接头力学性能的影响,并对高强钢一铝合金的中频逆变电阻点焊接头断口形貌进行机理分析。研究表明:当高强钢与铝合金的点焊热输入量较小时,热输入量增加有利于形成较大熔核直径;但增大到一定程度后,会逐渐稳定。同时,高强钢-铝合金电阻点焊熔核尺寸与其接头的正交拉伸、抗剪强度有一定关系,抗剪断裂出现在铝母材侧,断口形貌为明显的韧性断裂。 相似文献
2.
双相高强钢电阻点焊快速冷却过程中形成的淬硬马氏体会增加点焊接头脆性,产生熔核界面撕裂问题,降低接头力学性能与低周疲劳寿命.以1.4 mm双相钢DP600为例,采用残余在母材上的熔核面积百分比作为衡量电阻点焊熔核界面撕裂程度的评价指标,利用正交试验设计方法,研究不同焊接工艺参数对熔核撕裂程度的影响规律.通过对单因子分析,可知焊接电流对双相钢点焊接头撕裂程度的影响最大;通过交互作用分析,获得了减少焊点界面撕裂程度的最优工艺参数;最后通过试验验证,有效减少和避免焊点界面撕裂发生. 相似文献
3.
分别对1.5 mm厚的钛合金板进行胶接点焊和电阻点焊连接,获得了不同焊接电流下的胶接点焊和电阻点焊接头,从熔核的C扫描图像、接头的失效载荷和断口形貌等方面,对比分析了胶接点焊和电阻点焊的接头强度及失效样貌. 结果表明,通过观察A扫描信号的变化与C扫描图像的特征,能够很好的划分接头的热影响区、熔合区、熔核区以及检测出接头的熔核直径和焊接缺陷. 随着焊接电流(7.0~10.0 kA)的逐渐增大,接头熔核直径及失效载荷呈递增趋势;当焊接条件相同时,胶接点焊接头的熔核直径普遍大于电阻点焊接头,但接头的强度相当. 当电流在7.0~8.5 kA时,接头强度不足,熔核区的断口处出现大小不等的韧窝,呈现出韧性断裂特征;当电流为10.0 kA时,接头强度较高,主要呈现出韧性断裂与准解理断裂特征. 相似文献
4.
5.
6.
7.
8.
9.
DP590GA热镀锌双相钢电阻点焊接头性能 总被引:3,自引:2,他引:1
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. 相似文献
10.
电阻点焊接头质量在宏观上取决于熔核尺寸,在微观上则取决于点焊接头的组织状态,而两者都是由电阻点焊传热传质规律所决定的。文中采用数值模拟的方法对热冲压钢电阻点焊熔核形成过程进行研究。首先建立电阻点焊接头的有限元模型;然后模拟其熔核形成过程,建立点焊接头温度场分布及点焊熔核中心至热影响区的焊接热循环曲线;最后分析了点焊接头的组织特征及显微硬度分布,为控制点焊接头质量提供依据。 相似文献
11.
Microstructure and mechanical properties of dissimilar steel plate resistance plug welding joints 下载免费PDF全文
A new type of hybrid welding method called resistance plug welding (RPW) was firstly adopted to achieve the connecting of dissimilar steel,mainly as for the poor welding characteristics of high strength steel produced by increasing carbon,manganese,silicon,etc.Microstructures and mechanical properties of RPW joint were analyzed by optical microscope,micro-hardness test and shear tensile measurement.Experimental results indicate that the RPW joint has a rounded rectangle nugget,and the size is larger than elliptical nugget of resistance spot welding (RSW) joint;the hardness value of RPW joint is evenly distributed,accordingly there is no hard brittle phases;the shear tensile strength of RPW joint increases by 20% in comparison with RSW joint under the same welding conditions. 相似文献
12.
Alejandro Espinel Hernández Hipólito Carvajal Fals Valtair Antonio Ferraresi Louriel Oliveira Vilarinho 《Science & Technology of Welding & Joining》2013,18(8):607-613
The influence of polarity during resistance spot weld (RSW) of dissimilar lap joints on mechanical properties and failure mode is assessed in this work. A dissimilar lap joint was set using DP 600 dual phase steel with AISI 304 stainless steel. The experiments were performed on a medium-frequency direct current spot welding machine with proper data acquisition of voltage and welding current. Temperature evolution was also acquired by using IR camera. The mechanical properties of spot welds were evaluated by using a coach peel testing. The effect of welding current and welding time on mechanical properties was also evaluated. Correlations between polarity with the welding nugget size, failure mode, tensile strength, temperature evolution and dynamic resistance were analysed. The analysis confirmed that the polarity on dissimilar lap joints affects the behaviour of dissimilar RSWs. 相似文献
13.
《Science & Technology of Welding & Joining》2013,18(3):242-247
AbstractLap joints of dual phase steel sheets of 1·0 mm were prepared by adhesive bonding, spot welding and weld bonding processes using a one component epoxy base structural adhesive. Mechanical properties of the joints were evaluated by tensile shear and fatigue tests. The size of the weld nugget for both spot weld and weld bond was measured for different welding parameters (current, time) and compared. For identical welding parameters, weld bonded nuggets exhibit higher nugget diameter. Tensile shear strength of weld bonded joints is 40 and 58% higher than spot welded joints and 15 and 39% higher than adhesive bonded joints and for DP590 and DP780 steels respectively. Considering 106 cycles, the endurance limit of weld bonded joint is much higher than spot welded joint but smaller than adhesive bonded joints. Overall the performance of weld bonded joints is superior to those of resistance spot welding. 相似文献
14.
15.
Vehicle body structures are increasingly utilising multi-materials designs with advanced high strength steels (AHSS) and aluminium alloys. A robust process for joining aluminium alloys to AHSS based on resistance spot welding (RSW) is essential to widespread application of such bi-metallic structures in fuel-efficient vehicles. In this study, ultrasonic plus RSW was applied to join AA6022 to Zn-coated dual-phase steel DP980. During solid-state ultrasonic spot welding, an interface structure comprising multilayer, Al–Zn and Zn–Fe intermetallics formed due to alloying of aluminium with steel coating. Such structure was subsequently melted into the aluminium nugget, and new Al–Fe intermetallics formed during RSW. Ultrasonic plus resistance spot-welded joints had superior fracture energy than direct resistance spot-welded joints. 相似文献
16.
为避免热冲压高强钢电阻点焊在热输入较大时产生飞溅和满足激光点焊装配要求,提出一种将电阻点焊和激光点焊组合的新焊接工艺方法.通过电阻+激光组合点焊工艺获得了热冲压高强钢焊接接头,分析了接头各区域的显微组织、显微硬度分布、力学性能,并分析了断裂模式及其断裂机理.结果表明,电阻+激光组合点焊接头明显分为电阻焊接区和激光焊接区.母材和激光焊核区硬度值较大,与回火区对应的软化区硬度值下降约60%,激光环外侧软化区为拉剪断裂薄弱环节.此种组合工艺获得的焊接接头相对于单独电阻点焊或激光点焊强度和韧性都有明显提高. 相似文献
17.
《中国焊接》2021,(2)
The present paper investigates the welding forming, microstructure and shear tensile test of lap joints with large thickness ratio which were fabricated by laser screw welding(LSW) and resistant spot welding(RSW). The comparison was conducted on two kinds of lap joints, galvanized sheet and hot pressed steel(GS-HPS), galvanized sheet and high strength steel(GS-HS). The microstructure and fracture morphology were analyzed by optical microscope. It was demonstrated that with large thickness ratio the sound lap joint of GS-HS could be obtained by LSW regardless of the irradiation of laser beam from thick metal to sheet or otherwise, and the morphology shows it is better when the laser is irradiated on the thick metal. Nevertheless, when the laser beam was applied on thick metal of HPS, blind hole or blowhole was formed in the center of joint, which is attributed to the shrinkage during solidification of the molten pool. Small pores or dispersed porosity appeared on the faying face of the joint without predetermined gap which provides the degassing. However, the increase of predetermined gap could reduce the shear strength and nugget size. Two kinds of joints made by LSW have superior shear strength than those made by RSW when the laser were applied on galvanized sheet. 相似文献
18.
《Science & Technology of Welding & Joining》2013,18(5):386-392
AbstractThe weld expulsion is prone to occur and severely affects the nugget quality when the initial gap between dual phase (DP) steel sheets exist in resistance spot welding (RSW). To investigate the effect of initial gap on weld expulsion, a finite element model was developed to analyse the weld nugget formation process with different initial gaps for DP steels. An estimation method of expulsion occurrence based on the ratio of the nugget radius Rn and the contact radius Rc between sheets was proposed to get the critical initial gap without expulsion. The simulation and experimental results showed that the weld expulsion would not happen until the gap spacing reaches the critical value. The critical initial gap of DP steel is much smaller than that of low carbon steel. For both DP steel and low carbon steel, the critical initial gap would increase with the thickening of the steel sheet. 相似文献
19.
《Science & Technology of Welding & Joining》2013,18(4):329-336
AbstractThis paper investigates the source, magnitude and direction of magnetic force on the liquid nugget during resistance spot welding (RSW). High speed photography was used to observe the nugget formation process during half-sectioned RSW of steel (ferromagnetic substance) and aluminium alloy (paramagnetic substance). The induced magnetic force acting on half-sectioned and regular nugget was afterwards analysed and calculated. The results show that in the case of steel RSW, the magnetised workpieces generated a very strong magnetic field around the spot welding zone, while weak magnetic field appeared in the case of aluminium alloy RSW. This strong magnetic field causes a strong convection in the liquid nugget of steel even when the welding current is low. This strong convection will promote that the dimensions of nugget in the steel RSW become larger and closer to rectangle (observed on the cross-section) than in the aluminium alloy RSW. 相似文献