Microstructures and Properties of Copper to Stainless Steel Joints by Hybrid FSW

Abstract

The present research article is focused to investigate the heating-and cooling-assisted friction stir welding (FSW) on dissimilar copper to stainless steel joints along with normal FSW. Gas tungsten arc welding torch was applied for heating-assisted source in front of the FSW tool, wherein preheating current was varied as 20, 40, and 60 A with rest of constant FSW parameters. Similarly, cooling-assisted FSW was performed by compressed air and water behind the FSW tool for constant FSW parameters, wherein the compressed air flow rate was varied as 15 and 30 PSI and water cooling was applied with 75 ml/ min one after another. Weld properties of assisted approaches were compared with normal FSW on the scale of macrostructure and microstructure analysis, tensile testing, and microhardness properties. The obtained results reveal that the normal FSW of dissimilar copper to stainless steel joint was observed as superior relative to assisted approaches. Surface oxides were observed for the welds of heating-assisted FSW and cooling-assisted FSW of compressed air. Elimination of surface oxides was noted for FSW assisted by water cooling. Highest tensile strength was reported for normal FSW relative to heating-assisted FSW and cooling-assisted FSW. Tensile strength was deteriorated as cooling conditions increase. The microstructures of the stir zone were observed as metal matrix type with Cu matrix and SS particles, wherein SS particles were reported as in random distribution with its varying size. Major defects were reported around the largely dispersed SS particles inside Cu matrix.

The Joining of Copper to Stainless Steel by Solid-State Welding Processes: A Review

“…In this case, the researcher has employed the mica sheet beneath the workpiece [ 110 , 111 ]. Similarly, appropriate plastic deformation can also be obtained by applying heat-assisted FSW for Cu/SS joints [ 121 , 191 , 192 , 193 ]. The additional heat source, i.e., gas tungsten arc welding torch, ahead of the non-consumable rotating tool softens the base-materials [ 194 , 195 , 196 , 197 ].…”

Impact of speed of traverse during joining of CDA101 plates by FSW process

“…Another unique feature of this tool fabricated using M42 grade HSS is, it can last longer than M35, M2 grades of HSS [38,39]. The entire set of experimental investigations were carried out by employing a constant downward force of 6kN and the tool was made to spin at a consistent speed of 1100 rpm and the tool was made to traverse at 6 distinctive rates including 20, 25, 30, 35, 40 and 45 mm/min.…”

Parametric studies on laser additive manufacturing of copper on stainless steel

“…In the present work, FE analysis is carried out for deposition of six layers with six tracks per layer on a SS 304L substrate. The cooling rate at the centre of the track of each layer is evaluated by using Equation (3). Further, the cooling rate at each cell is evaluating considering the temperature difference at cell and interaction time (τ) given as 17 :…”

“…Various joining techniques are reported in the published literature to develop dissimilar joint of Cu and SS. [2][3][4][5][6][7] Magnabosco et al investigated microstructural transformation and element diffusion at interface of Cu-SS dissimilar joint built using electron beam welding. 7 Defects such as porosity, unmelted iron particle and microfissuring were observed at interface due to large difference in thermo-physical properties.…”