Study of the microstructure, mechanical properties and forming behaviour of graphene-interlayered resistance spot-welded patch blanks of dissimilar ultra-low carbon cold-rolled and dual-phase steel sheets
Year: 2024
Type: article
Abstract: In the present study, the application of resistance spot welding (RSW) for the fabrication of patch blanks using similar CR-210/CR-210 steel and dissimilar CR-210/DP-780 steel combinations by graphene nanoplatelets (GNPs) coating as an interlayer was reported. The desired nugget pull-out failure from the weaker CR-210 steel side of the weldments in lap shear tests was observed at a 9 kA welding current. Also, a joint strength improvement of ~36% in the lap shear test was obtained at this welding current owing to the introduction of GNPs as an interlayer. Hence, 9 kA was chosen for the fabrication of similar and dissimilar steel combination patch blanks by RSW with and without GNPs as an interlayer. The microstructural characterisation of the cross-sectioned sample by scanning electron microscopy revealed the existence of a lath martensitic structure at the fusion zone (FZ). Grain refinement and the presence of strain localisation in the FZ were confirmed by the electron back-scattered diffraction (EBSD) technique. Transmission electron microscopy depicted the dislocation pile-ups at the grain boundaries which was accompanied by the formation of nano-precipitates. The interfacial shear load transfer from the matrix to the reinforcement was also illustrated for the GNP-coated weldment fabricated at 9 kA. Further, stretch forming of the patch blanks indicated that the maximum strain occurred at the thinner sheet away from the spot welds. However, the incorporation of the GNPs as an interlayer had a marginal effect on the formability of the patch blanks. Hence, patch blanks of dissimilar CR-210 and DP-780 steel sheets with and without GNPs as an interlayer can be utilised for the automobile body components for localised strengthening so as to avoid failure.
Source: Materials Today Communications
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,430
OpenAlex ID: W4405750720