Welding time effect on mechanical properties of automotive sheets in electrical resistance spot welding

2008 ◽  
Vol 29 (7) ◽  
pp. 1427-1431 ◽  
Author(s):  
S. Aslanlar ◽  
A. Ogur ◽  
U. Ozsarac ◽  
E. Ilhan
Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 710 ◽  
Author(s):  
Khuenkaew ◽  
Kanlayasiri

This research examines the weldment characteristics and mechanical properties of lap joints of SUS316L/SUS425 stainless steels using resistance spot welding under variable weld currents and welding times. The weld current was varied between 7.0, 8.5, and 10.0 kA, and the welding time between 25, 38, and 50 cycles. The weldment quality characteristics under study were the depth of fusions, indentation depths, and nugget diameter, and the mechanical properties included the tensile shear force (TSF) and micro Vickers hardness. Phase transformation and solidification were characterized using scanning electron microscopy and energy dispersive X-ray spectrometry, together with Schaeffler and pseudo-binary predictive phase diagrams. The results revealed that the weldment quality was positively correlated with weld current and welding time, as were the TSF and micro hardness. The optimal welding condition was achieved under a 10.0 kA weld current and 25-cycle welding time. Under the optimal condition, the fusion zone exhibited compression-direction columnar grains consisting of austenite, ferrite, and martensite and the solidification was of ferrite plus Widmanstatten austenite.


ROTASI ◽  
2013 ◽  
Vol 15 (2) ◽  
pp. 44
Author(s):  
Haikal Haikal ◽  
Triyono Triyono

Resistance spot welding (RSW) is the most widely used for joining thin sheet metals in automotive industry. Various applications of dissimilar materials and thicknesses were commonly found in many spot welding processes especially in the manufacture of car body. The resistance spot welding of dissimilar materials are generally more challenge than similar materials due to differences in the physical, chemical, and mechanical properties of the base metals. Differences of materials have an impact on heat input generated at the spot welding. Diameter of the weld nugget size is influenced by several parameters such as electric current, welding time, different types of material, and the thickness of the plate. Nugget diameter will influence on physical and mechanical properties weld such as microstructure, shear strength and hardness. For practical use, various industrial standards have recommended a minimum weld size for a given sheet thickness, mostly in the form of tables. For example the American Welding Society (AWS), Society of Automotive Engineering (SAE) and the American National Standards Institute (ANSI). They were only suitable to be apllied on the similar metal and thickness joint because in this joint, symetrical nugget will be formed. Meanwhile a type of dissimilar metal that joined by spot welding method will result in the asymetrical nugget. This paper aims to review the results of researchs on the similar and dissimilar resistance spot welded joint to evaluate the use of similar metals weld parameters and standards on the dissimilar metals weld. It was determined that parameters welding such as electric current, welding time, and the standard for similar metals weld can not be applied on the dissimilar metals weld. The asymetrical nugget shape decreased shear strength on the weld nugget. The most important factor that was considered on the dissimilar metals weld to make high quality weld joint was nugget diameter. If the nugget diameter weld increased the strength of welding will increase.


2016 ◽  
Vol 1138 ◽  
pp. 153-158
Author(s):  
Mihai Boca ◽  
Gheorghe Nagit ◽  
Laurenţiu Slătineanu

The resistance spot welding process represents the welding technology used to obtain assemblies trough welded spots characterized by adequate mechanical properties. This assembly process is used mainly into the automotive, petroleum and naval industries. It is applied due to the significant advantages concerning the technology and service properties of the obtained assembly. This paper purposes a study concerning the micro hardness change of an assembly made by resistance welding spot. The entire process of plastic deformations together with the solidification step developed in the presence of the heat generated during welding process determines the mechanical characteristics of the welded spot and, of course, of the assembly obtained. In such conditions, depending on the changes developed during the welding process, the micro hardness of the welded spot varies between the fusion area (FA) and heat affected zone (HAZ). In this way, the graphical representation of the micro hardness repartition gives clues about the weakness areas which don’t correspond to the requirements. As input factors, in this study, the values of current intensity, the electrical current time and the force pressure were considered. In order to solve the proposed problem and to graphically highlight the variation of the micro hardness obtained for welded points, it was used a classical welding device and a micro hardness device analyzer. The graphical representation shows that the micro-hardness and, as a consequence, some mechanical properties changes in the specified region and in the entire mass of the welded spot changes. In this way, the structure of welded spot is characterized by a variation of the hardness in the interest areas.


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