Analysis and Optimization of Resistance Spot Welding Parameter of Dissimilar Metals Mild Steel and Aluminum Using Design of Experiment Method

Abstract

This research aims to study the effect of parameters of the resistance spot welding (RSW) on the shear strength of the spot weld for different metals {AA 6061-T6 and AISI 1010} using (0.5 and 0.7 mm) thickness. Three values for each welding parameters (welding current, electrode force, squeeze time and welding time) are to be used. The effect of those parameters have been analyzed by Minitab program by design of experiments (DOE) in order to determine and reduce the number of specimens required to achieve the tests. The design of experiment method which used was Taguchi method The experimental tests that had been done are shear, Microhardness and microstructure tests. It was found that the maximum shear force in welding of dissimilar metals (AA 6061-T6 with AISI 1010) is (F = 1.14 KN for t = 0.7 mm). This value has been optimized to reach (F =1.24 KN) using DOE. The minimum shear force was (F = 0.25 KN in t = 0.5 mm). In general, increasing the welding current and sample thickness gave an increase in the shear force, but at the same time the reduction in shear force have occurred during the increasing in electrode force, squeeze time and welding time. From Microhardness tests, the maximum value of hardness is found at the center of nugget zone (NZ) and it reduces slightly until reaching constant values away from NZ. ‫ﺗﺤﻠﯿﻞ‬ ‫ﻣ‬ ‫وأﻣﺜﻠﺔ‬ ‫ﺘﻐﯿﺮات‬ ‫ﻟﺤﺎم‬ ‫اﻟﻨﻘﻄﻲ‬ ‫اﻟﻤﻘﺎوﻣﺔ‬ ‫ﻟﻠ‬ ‫اﻟﻤﺨﺘﻠﻔﺔ‬ ‫ﻤﻌﺎدن‬ ‫اﻟﻤﻄﺎوع‬ ‫ﺣﺪﯾﺪ‬ ‫واﻷﻟﻤﻨﯿﻮم‬ ‫ﺑﺎﺳﺘﺨﺪام‬ ‫اﻟﺘﺠﺎرب‬ ‫ﺗﺼﻤﯿﻢ‬ ‫طﺮﯾﻘﺔ‬ ‫اﻟﺨﻼﺻﺔ‬ : ‫ھﺬا‬ ‫ﻣﺘﻐﯿﺮات‬ ‫ﺗﺄﺛﯿﺮ‬ ‫ﻟﺪراﺳﺔ‬ ‫ﯾﮭﺪف‬ ‫اﻟﺒﺤﺚ‬ ‫ﻟﻤﻮاد‬ ‫اﻟﻠﺤﺎم‬ ‫ﻟﻨﻘﻄﺔ‬ ‫اﻟﻘﺺ‬ ‫ﻣﻘﺎوﻣﺔ‬ ‫ﻋﻠﻰ‬ ‫اﻟﻨﻘﻄﻲ‬ ‫اﻟﻤﻘﺎوﻣﺔ‬ ‫ﻟﺤﺎم‬ ‫ﻣﺨﺘﻠﻔﺔ‬ {AA 6061-T6 and AISI 1010 } ‫ﺑﺎﺳﺘﺨﺪام‬) ‫ﺳﻤﻚ‬ 0.5 , 0.7 .‫ﻣﻠﻢ‬ (‫ﻣﻦ‬ ‫ﻗﯿﻢ‬ ‫ﺛﻼث‬ ‫اﺳﺘﺨﺪﻣﺖ‬ ‫اﻟﻤﺘﻐﯿﺮات‬ ‫ھﺬه‬ ‫ﺗﺄﺛﯿﺮ‬ ‫ﺗﺤﻠﯿﻞ‬ ‫(.ﺗﻢ‬ ‫اﻟﻠﺤﺎم‬ ‫وزﻣﻦ‬ ‫اﻟﻀﻐﻂ‬ ‫زﻣﻦ‬ , ‫اﻟﻘﻄﺐ‬ ‫ﻗﻮة‬ , ‫اﻟﻠﺤﺎم‬ ‫ﺗﯿﺎر‬) ‫اﻟﻠﺤﺎم‬ ‫ﻣﺘﻐﯿﺮات‬) ‫ﺑﺮﻧﺎﻣﺞ‬ ‫ﺑﺎﺳﺘﺨﺪام‬ Minitab ‫اﻟﺘﺠﺎرب‬ ‫ﺗﺼﻤﯿﻢ‬ ‫ﺑﻄﺮﯾﻘﺔ‬ ((DOE) ‫اﻟﻌﯿﻨﺎت‬ ‫ﻋﺪد‬ ‫وﺗﻘﻠﯿﻞ‬ ‫ﺣﺴﺎب‬ ‫ﻟﻐﺮض‬ .‫اﻻﺧﺘﺒﺎرات‬ ‫ﻓﻲ‬ ‫اﻟﻼزﻣﺔ‬ ‫ھﻲ‬ ‫اﺳﺘﺨﺪﻣﺖ‬ ‫اﻟﺘﻲ‬ ‫اﻟﺘﺠﺮﺑﺔ‬ ‫ﺗﺼﻤﯿﻢ‬ ‫طﺮﯾﻘﺔ‬ ‫طﺮﯾﻘﺔ‬ ‫ﺗﺎﻛﻮﺷﻲ‬ .(‫اﻟﻤﺠﮭﺮﯾﺔ‬ ‫اﻟﺒﻨﯿﺔ‬ ‫وﻓﺤﺺ‬ ‫اﻟﺪﻗﯿﻘﺔ‬ ‫اﻟﺼﻼدة‬ , ‫اﻟﻘﺼﻲ‬ ‫اﻟﺸﺪ‬ ‫)اﺧﺘﺒﺎر‬ ‫ھﻲ‬ ‫اﻟﻤﻨﺠﺰة‬ ‫اﻟﻌﻤﻠﯿﺔ‬ ‫اﻟﺘﺠﺎرب‬ ‫ان‬ ‫وﺟﺪ‬ ‫اﻟﻤﺨﺘﻠﻔﺔ‬ ‫اﻟﻤﻮاد‬ ‫ﻟﺤﺎم‬ ‫ﻓﻲ‬ ‫ﻗﺺ‬ ‫ﻗﻮة‬ ‫أﻗﺼﻰ‬ {AA 6061-T6 and AISI 1010 }) ‫ھﻲ‬ F = 1.14 KN ‫ﺑﺴﻤﻚ‬ t = 0.7 mm) ‫اﻟﻰ‬ ‫اﻟﻘﯿﻤﺔ‬ ‫ھﺬه‬ ‫ﺗﺤﺴﯿﻦ‬ ‫ﺗﻢ‬ .(F = 1.24 KN ‫اﻟﺘﺠﺎرب‬ ‫ﺗﺼﻤﯿﻢ‬ ‫طﺮﯾﻘﺔ‬ ‫ﺑﺎﺳﺘﺨﺪام‬ ((DOE) ‫ﻗﯿ‬ ‫اﻗﻞ‬ .) ‫ﻛﺎﻧﺖ‬ ‫ﻗﺺ‬ ‫ﻗﻮة‬ ‫ﻤﺔ‬ F = 0.25 KN ‫ﺑﺴﻤﻚ‬ t = 0.5 mm .(‫اﻟﻨﻘﺼﺎن‬ ‫اﻟﻮﻗﺖ‬ ‫ﺑﻨﻔﺲ‬ ‫وﻟﻜﻦ‬ , ‫اﻟﻘﺺ‬ ‫ﻗﻮة‬ ‫ﻓﻲ‬ ‫زﯾﺎدة‬ ‫اﻋﻄﻰ‬ ‫اﻟﻤﻌﺪن‬ ‫وﺳﻤﻚ‬ ‫اﻟﺤﺎم‬ ‫ﺗﯿﺎر‬ ‫زﯾﺎدة‬ , ‫ﻋﺎﻣﺔ‬ ‫ﺑﺼﻮرة‬ .‫اﻟﻠﺤﺎم‬ ‫وزﻣﻦ‬ ‫اﻟﻀﻐﻂ‬ ‫وزﻣﻦ‬ ‫اﻟﻘﻄﺐ‬ ‫ﻗﻮة‬ ‫زﯾﺎدة‬ ‫ﺧﻼل‬ ‫ﺣﺼﻞ‬ ‫اﻟﻘﺺ‬ ‫ﻗﻮة‬ ‫ﻓﻲ‬ ‫ﺧﻼل‬ ‫ﻣﻦ‬ ‫اﻟﺼﻼدة‬ ‫ﺗﺠﺮﺑﺔ‬ ‫ﺛﺎﺑﺘﺔ‬ ‫ﻗﯿﻤﺔ‬ ‫ﺗﺼﻞ‬ ‫ﺣﺘﻰ‬ ‫ﺗﺪرﯾﺠﯿﺎ‬ ‫وﺗﻘﻞ‬ ‫اﻟﺼﻠﺒﺔ‬ ‫اﻟﻤﻨﻄﻘﺔ‬ ‫ﻣﺮﻛﺰ‬ ‫ﻓﻲ‬ ‫ﻟﻮﺣﻈﺖ‬ ‫ﻟﻠﺼﻼدة‬ ‫ﻗﯿﻤﺔ‬ ‫أﻗﺼﻰ‬ (‫)اﻟﻤﺠﮭﺮﯾﺔ‬ .‫اﻟﻤﻨﻄﻘﺔ‬ ‫ھﺬه‬ ‫ﻋﻦ‬ ‫ﺑﻌﯿﺪا‬ INTRODUCTION esistance spot welding (RSW) emerged in the 1950s, and is today the main assemblage method in the automotive manufacturing. RSW is considered as the dominant process for joining sheet metals in automotive industry. Typically, there are about 2000-5000 spot welds in a modern vehicle. Simplicity, low cost, high speed (low process time) and automation possibility are among the advantages of this process [1]. To make a spot weld, two or additional metal sheets are pushed jointly by electrodes, and an electric current is passed. Heat is engendered by the metal resistance, and the sheets are welded in concert by resources of restricted metal fusion. No welding metal is extra in this method. Three regions are recognized in a spot weld: a weld nugget with cylindrical profile, a heat affected zone (HAZ) and the base metals sheets. These regions have different metals properties. For example, the yield stress in the nugget is up to three time's upper than in the base metals, and the plastic properties of the HAZ are non-homogeneous [2]. Resistance spot welding is a welding process wherein coalescence is formed by the heat acquired from resistance to the electric current flows during the work portions held together below pressure from electrodes. The control function of the welding machine defines the welding cycle. The particular steps controlled are squeeze, welding, and hold time [3]. The domestic heating generated at the weld zone is due to the flow of RSW machine current through the resistance of the welded metals. The pressure through the electrode tips, in which the current is flow, carries the exerted portions to be welded at close connection before, during and after the current cycle welding. The requisite magnitude of the current time is selected depending on the metals thickness and type, the quantity of flow current, and the area of the cross-sectional for the contact surfaces of welding tip [4]. The high thermal and electrical conductivity of aluminum require higher current and shorter weld time, typically 25% of that used to RSW steel. Accurate control and synchronization of current and electrode force is required due to the narrow weld temperature range [5].