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Advanced high strength steels (AHSS) are multiphase steels that contain various concentrations of ferrite, bainite, martensite, and retained austenite phases. The unique physical characteristics of AHSS present some challenges to welding and bonding processes. AHSS have tendency to change microstructure and mechanical properties by any welding process like other steels. Based on the significant applications in various industries, the experimental works are carried out on one of AHSS materials, EN-10149-2 S700MC, with thickness of 2 mm steel sheet metal by MIG welding process parameters such as current, voltage, and welding speed. For all combinations of process parameters, the butt joints are fabricated. The butt joints are inspected through different nondestructive testing for defects detection. All the defect-free joints are characterized through microstructure (at different zones of joint), hardness, and tensile tests. From the obtained mechanical test results, the process parameters are optimized through design of experiment techniques (DoE). The analysis from DoE method is used to identify which parameter is the most significant among all parameters. Confirmatory test is also done by taking the optimal parameters and the result shows that the improvement of the response variables is acceptable and also shows that the method that is used for optimization was valid.

Friction stir consolidation (FSC) is a promising manufacturing process for metal matrix hybrid composites (MMHC) with excellent mechanical properties. The originality of this study involves the exploration of the fabrication technique (FSC), the selection of materials and the optimization of wear behavior via a systematic investigation of the process parameters. The aim of this study was to optimize and investigate the wear behavior of MMHCs fabricated using FSC. The optimum sample was nominated for thermogravimetric analysis (TGA) and wear morphology analysis using SEM imaging. Material compositions of 7.5%wt of SiC, 7.5%wt of ZrO2 and 85%wt of AZ61 were considered for the experimental investigation. The RSM Box–Behnken design followed by a genetic algorithm (GA) was implemented to optimize the process parameters of sliding distance, speed and load at 350 m, 500 m and 650 m; 220 rpm, 240 rpm and 260 rpm; and 20 N, 30 N and 40 N, respectively. The RSM Box–Behnken result showed that the minimum wear rate of 0.008 mg/m was obtained at 350 m, 20 N and 240 rpm, whereas GA predicted the optimum parametric setup at 350 m, 20 N and 220 rpm. Additionally, TGA showed the material's thermal stability from 375 °C to 480 °C. Generally, MMHCs exhibited a promising wear performance, proving the effectiveness of the FSC. [ABSTRACT FROM AUTHOR]

There is high demand of Aluminium material for various engineering applications but the main problem being low wear and corrosion resistance. Laser beam application for surface modification of engineering materials gets high attention in research and industries due to superior surface performance for wear and corrosion resistance. In the present research article, an attempt has been made to improve the properties of Aluminium by laser surface alloying technology. Laser surface alloying of commercially pure aluminium with titanium and zinc metal powders at 50% combination has been conducted using CO2 laser power from 1600 to 2000 W. The experiments have been planned through design of experiment using Response Surface Methodology (RSM). The mathematical modelling and optimisation of process parameters such as specific laser power scan speed and heat input for optimum value of Micro hardness has been carried out using RSM with three factors and five levels. The statistical significance of the data has been carried out using Analysis of Variance (ANOVA).The alloy made by Al-TiZn shows improved hardness by 47% due to good laser surface alloying which has created dendrite microstructure without any metallurgical defects. The optimised value of laser energy density was found to be 37 J/mm2. It has been investigated that the optimum values of laser speed and heat input are 84 m/s and 61.50 watt respectively for micro hardness value of 56HV. Hardness decreases from top alloy zone towards substrate material since high energy creates more depth where the concentration of alloying elements is less. The friction coefficient of Al-TiZn alloy was found to be less by 23% than unalloyed aluminium substrate. The depth of laser alloyed has been increased with laser power and heat input from laser beam. Higher electron microscopy analysis shows that a sound alloying has been created without surface and subsurface defects. The present investigation is expected to help automobile and aerospace industries where the wear and corrosion resistance of the material are of major concern. [ABSTRACT FROM AUTHOR]