Adhesive weld bonding of interstitial free steel at spot welding for automotive application

Abstract

In this study, the effect of adhesive bonding on strength and strength-ductility behaviour of welding joint in electrical resistance spot welding of 7315 grade IF steel sheets was investigated. 7315 grade (DIN EN 10130-1999) IF steels were adhesively bonded and different welding current and welding cycle conditions were performed in welding process. For adhesive bonding, Loctite Terostat 9120-Grey and Terostat 9220-Black grade adhesive bonders were used. Additionally, adhesively bonded joint samples were also performed without welding. Microstructure and tensile-shear tests of the adhesively bonded and welded materials were evaluated. Failure modes of the weld bonded tensile sheared samples were observed to be different from only welded samples. Experimental results have shown that with the increase in the weld time and weld current, the effect of the adhesive weld bonding on tensile performance also increases.K e y w o r d s : IF (Interstitial-Free) sheet steel, resistance spot welding, adhesive weld bonding, tension test

Experimental investigation of the mechanical behaviour of spot welding–adhesives joints

“…The hardness values decrease gradually from the base metal to the HAZ/base metal interfacial region as a result of internal strain energy being relieved due to weld heat input. Martensitic transformation may occur in the HAZ that is exposed to heat and in the weld metal that is exposed to melting and solidification for a short time [12] and nugget formation depends on many variables, but the welding heat input is probably the most effective parameter [14].…”

Weldability of electrogalvanized versus galvanized interstitial free steel sheets by resistance seam welding

“…The nearest thing to ductility measurement is the hardness test since the hardness of metal is usually an indication of its ductility [21]. 13 shows the effect of welding current on the microhardness of the galvanized steel observed at the currents of 23,600 A and 26,800 A. Hardness rose from the base metal towards the center of the weld where the maximum hardness was reached.…”

Evaluation of the physical properties of spot welding using ultrasonic testing

“…Many researchers have studied spot welding process by experimental and numerical techniques in order to increase the quality of products [6]. Hardness is one of the most important factors that affect spot weld quality [7]. The weld nugget or fusion zone (FZ) (which is melted during welding process and is resolidified showing a cast structure) provides the highest hardness values, and this is followed by the heat-affected zone (HAZ) (which is not melted but undergoes microstructural changes) and base metal (BM) [4].…”

“…Also, it is reported that the pearlite-ferrite microstructure is harder than ferrite microstructure [9]. Generally, grain coarsening was observed at the weld nugget and HAZ of spot-welded samples [7].…”