Microstructure and Mechanical Properties of Spot Welding Joint of Dissimilar High Strength Steel
01 May 2015-pp 269-274
About: The article was published on 2015-05-01. It has received 3 citations till now. The article focuses on the topics: Welding & Electric resistance welding.
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TL;DR: In this article, a three-layer structure consisting of ultra-high strength steel and high strength steel was resistance spot welded and the authors described the macro characteristics of the joint in terms of nugget diameter, offset, penetration rate, indentation depth, and thickness thickness.
Abstract: In this paper, a three-layer structure consisting of ultra-high strength steel and high strength steel was resistance spot welded. Macro characteristics of the joint were described in terms of nugget diameter, nugget offset, penetration rate, indentation depth, the indentation diameter, and thickness thinning rate. The results show that the smallest nugget diameter is about 6.3 mm and nugget offset is ignorable. Welding parameters have discrepant influence on penetration rate. The maximum penetration rate is about 71 %. Indentation diameter ranges from 6 to 8.6 mm and increases with welding parameters. Indentation depth varies with welding parameters and reaches a maximum value 1.3 mm. Because of the delay of deformation, welding time and electrode force have little effect on thickness thinning rate when they are in relatively low level. However, thickness thinning rate increases with welding time and electrode force when they are in high level, which is like the trend in welding current. The maximum thickness thinning rate is about 33 %.
19 citations
Cites background from "Microstructure and Mechanical Prope..."
...The chemical composition and mechanical properties of base metals are shown in Tables 1 and 2 [18, 19]....
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...%) [18, 19]...
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...Table 2 The mechanical properties of B1500HS and B250P1 steel [18, 19] Materials Tensile strength (MPa) Yield strength (MPa) Elongation (%)...
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TL;DR: In this paper, the macrostructure and microstructure of welding joints were observed through optical microscope and scanning electron microscope, and the mechanical performances of welding joint were studied by means of shear and cross tension test.
Abstract: Ultra-high strength hot stamped steel B1500HS and cold rolled high strength steel B250P1 with unequal thickness were resistance spot welded. The macrostructure and microstructure of welding joints were observed through optical microscope and scanning electron microscope. The mechanical performances of welding joints were studied by means of shear and cross tension test. The results show a single nugget about 7.6mm in size form and nugget shifts towards B1500HS side. Martensite form in nugget and the heat affected zone on B1500HS side, which provides the both parts higher strength than B250P1. All welding joints are pulled out in both shear and cross tension test. Bigger nugget is the most important controlling factor for shear strength. The shape of nugget has distinct effect on the properties of joints under cross tension condition.
2 citations
Cites background from "Microstructure and Mechanical Prope..."
...The chemical composition and mechanical properties of two raw materials were shown in Table1-2 [8]....
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TL;DR: In this paper, a three-sheet stackup structure consisting of B1500HS and B250P1 dissimilar high-strength steel was produced by resistance spot welding and the failure mode and energy absorption ability of two typical samples were investigated in typical loading state such as shear and cross-tension test.
Abstract: A three-sheet stackup structure consisting of B1500HS and B250P1 dissimilar high-strength steel was produced by resistance spot welding. The failure mode and energy absorption ability of two typical samples were investigated in typical loading state such as shear and cross-tension test. Moreover, the fracture characteristics were observed by scanning electron microscopy and the fracture process was analyzed based on the loading state. Results show two samples fracture in interfacial mode or pullout mode in shear test and fracture only in pullout mode in cross-tension test. Despite the different fracture modes, fractured sample shows ductile characteristics during mechanical tests. Compared with the sample fractured in interfacial mode, sample fractured in pullout mode has higher ultimate load and energy absorption ability in shear test. Moreover, sample absorbs more failure energy in cross-tension test than that in shear test because of the deformation of structure in cross-tension test. Both carbon equivalent and welding conditions affect the hardness of the fusion zone—a lower CE value leads to a softer HAZ which helps to promote pullout failure in the cross-tension test.
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TL;DR: Wang et al. as discussed by the authors improved the weldability of dual-phase steel by adjusting the electrode force during spot welding process, and they showed that the width of weld lobe diagram can be nearly doubled.
39 citations
Journal Article•
TL;DR: In this article, the effect of welding current on the welding performance of ultra high strength steel sheet by hot stamping was investigated and the influence of electric current mode on the joint fracture location and weld central segregation was discussed.
Abstract: Spot welding of ultra high strength steel sheet by hot stamping was investigated.The effect of welding current on the welding performance,i.e,pressing depth,nugget diameter,penetration rate,and tensile fracture force were studied.Moreover,the influence of electric current mode on the joint fracture location and weld central segregation was discussed.The causes of HAZ softening and weld central segregation were also analyzed.The results indicated that the steel possessed good spot welding properties.
4 citations
Journal Article•
TL;DR: In this article, the influence of the primary welding parameters affecting the heat input such as; peak current on the morphology, microhardness, and tensile shear load bearing capacity of dissimilar welds between Low Carbon steel and High Strength Low Alloy (HSLA) steel has been investigated in this study.
Abstract: The resistance spot welding of dissimilar materials is generally more challenging than that of similar materials due to differences in the physical, chemical and mechanical properties of the base metals. The influence of the primary welding parameters affecting the heat input such as; peak current on the morphology, microhardness, and tensile shear load bearing capacity of dissimilar welds between Low Carbon steel and High Strength Low Alloy (HSLA) steel has been investigated in this study. This study has been done in three stages: First, welding performed on Low Carbon steel, then, on HSLA steel, after that, on a combination of both. During this study only welding current has been changed and other parameters are kept constant. Bearing capacity, hardness and weld nugget size of material shows a linear relationship with welding current, also weldability of low carbon steel with HSLA steel was found tobe satisfactory. At 8KA welding current, bearing capacity shows a maximum value (in Kg) of 270 for low carbon steel, 230 for HSLA steel, and 205 for a combination of both.
2 citations