Strength of spot‐welded steel sheets in corrosive environment

Abstract

The load bearing capacity (LBC), often referred to as strength, of spot-welded joints on as-received and pre-strained sheets of an interstitial free (IF) steel has been examined under 3.5% sodium chloride solution using tensile-shear (TS) specimens. These tests have been carried out under three different test conditions: (i) after immersing the samples in the solution for various duration of time, (ii) at various slow strain rates by keeping the samples in solution, and (iii) at slow strain rate under in situ hydrogen charging. Analyses of the results infer that (i) increased duration of immersion of the samples in aggressive environment decreases their LBC but increases their extension corresponding to the maximum load (EML), (ii) slow strain rate tests in the solution indicate marginal decrease of LBC and EML of the spot-welds, (iii) the LBC and EML of the spot-welds of pre-strained sheets decrease considerably with cathodic hydrogen charging while EML of the spot-welded joints on the as-received sheets is found to improve, and finally, (iv) the detrimental effect of corrosive environment increases with increased pre-strain of the investigated sheets. These observations have been discussed together with post-failure examinations of the broken fractured surfaces, which have assisted in understanding their failure mechanism.

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

“…6. The micro hardness values vary by approximately 200 HV in the nugget and 30 HV (in the base metal, similar to values determined by Mukhopadhyay et al [8]. It was found that the hardness values for the selected parameters were similar, with a low influence of current and welding time, according to Chakraborty et al [13].…”

“…This welding provides a coherent coupling of two or more sheets by fusing between the metal base in the overlapping region, transmitting in a safe and efficient efforts one another structure [5][6][7]. The difficulty of resistance spot welding for galvanized steel sheets rests with the limited or rigorous process specifications in terms of the welding production line [8].…”

Influence of Welding Parameters in Substrate/Coating of Galvanized Sheets Using Resistance Spot Welding

“…Resistance Spot Welding (RSW) is widely used in the automotive and aerospace industries and in manufacturing of the structural components of metro-rail vehicles. While new forms and joining processes, such as laser and resistance welding and the indirect use of adhesives are being developed and used, resistance spot welding is still predominant [1][2][3][4][5][6][7][8]. The main attraction for the widespread use of resistance welding are its simplicity, speed, ease of operation, absence of complex apparatus for execution and the ease with which this process can be adapted for automated manufacturing lines.…”

“…This welding provides a coherent coupling of two or more sheets by fusing between the metal base in the overlapping region, transmitting in a safe and efficient efforts one another structure [1][2][3]. The difficulty of resistance spot welding for galvanized steel sheets rests with the limited or rigorous process specifications in terms of the welding production line [5].…”

“…The generation of heat in the weld results from the combined action of three parameters expressed in eq. 1 [5].…”