Abstract The aim of this work is to examine the effect of TiO2 nanoparticles-coated E7018-H4R electrode on microstructure and strength of A-1011 steel welded joints. The SMAW process was used to join the base metal and output responses including UTS, hardness, % elongation, and residual stresses of joints have been evaluated. The effects of SMAW parameters such as welding current, welding speed and dipping time of electrodes in TiO2 solution on mechanical responses and microstructure have been analyzed through RSM with central composite design. Mathematical models have also been developed. Results revealed that tensile strength has been primarily influenced by welding current followed by dipping time and welding speed. The maximum tensile strength of 509 MPa, hardness of 230 HV and percentage elongation of 23% has been achieved by using 60 min dipping time of electrodes in TiO2 solution. The optimum combination of parameters, i.e., welding current of level 2 (130 A), welding speed of level 2 (35 cm/min), and Dipping time of electrodes in TiO2 solution of level 2 (60 min) has been attained. The residual stresses results showed that the specimen welded with coated electrode has less residual stress value 142.32 MPa as compared to specimen with uncoated electrode (179 MPa). The optical and scanning electron microscopic (SEM) analysis confirmed the presence of TiO2 nano particles in the welded zone. The EDX analysis confirmed the presence of Ti peaks, along with Mn and Si, leading to grain refinement and enhanced mechanical properties.
Ahmad et al. (Tue,) studied this question.