Friction stir processing of nanofiller assisted AISI 1010 steel-CDA 101 copper dissimilar welds: a strength factor approach

Abstract

In this research study the effects of adding nano fillers such as SiO2, graphene nanoplatelets (Gnps) and biochar on to the weld pool of dissimilar AISI-SAE 1010 Steel- CDA 101 copper were investigated. The main aim of this research study was to investigate the effect of adding ceramic and carbon rich secondary reinforcements on to the friction stir weld (FSW) pool of dissimilar metals and its relative outcomes. The mechanical properties such as tensile strength, yield strength, % of elongation, hardness and fatigue strength were investigated in the form of the strength factor approach. According to the results, the highest strength factor of 98 was obtained for welds made using Gnps of about 1.0 wt.% with constant axial load of 5 kN, traverse speed of 30 mm/min, rotational speed of 900 rpm, dwell time of 5 s and plunging depth of 0.2 mm. The highest tensile strength of 225 MPa and a fatigue strength of 168 MPa was noted for the weld using 2 wt.% Gnps in the weld pool. However, the biochar addition of 2.0 wt.% on to the weld bead positioned the second highest strength factor of 88 due to its solid lubricity. In all the welding processes, large doses of fillers produced undesirable strength factor values. The microstructure of both the weld and tool shows desirable effects for nanoparticle assisted welds. The HAZ and TMAZ grains were refined due to the inclusion of the nanoparticles. The result shows that naturally acquired biochar nanoparticles have the potential of replacing high cost nanofillers in joining metals with more than 85% close to the high cost fillers for the same output. These properties improved dissimilar copper-steel welded plate joints that could be used in automotive, defence, aerospace and structural applications.