Influence of processing variables on fabrication of AA7475/B ₄ C/Al ₂ O ₃ hybrid surface composites via FSP

The motive of this research is to fabricate AA7475/B4C/Al2O3 hybrid surface composites (HSCs) using friction stir processing (FSP) for various applications in aerospace, marine, and automotive industries. The research systematically varied key processing variables, including rotational speed (900–1300 rpm), feed rate (30–60 mm/min), and reinforcement ratios (from 30% B4C and 70% Al2O3 to 70% B4C and 30% Al2O3), to optimize responses such as ultimate tensile strength (UTS), tensile elongation (TE), and microhardness (MH). A face-centered central composite design (FCCCD) of response surface methodology (RSM) was employed to develop mathematical models correlating the input parameters with the response variables. An analysis of variance (ANOVA) was conducted to assess the effects and interactions of the processing parameters on the composite properties. A validation test confirmed the reliability of these optimal conditions. ANOVA results indicated that the tool rotational speeds had the most significant effect on the tensile, ductility, and hardness properties of the HSCs. However, changes in feed rate and reinforcement ratio had minimal impact on these properties. The study identified optimal conditions for different responses: UTS of 452.62 MPa, TE of 6.89%, and MH of 168.52 HV at a rotational speed of 1300 rpm, feed rate of 45 mm/min, and a 50:50% reinforcement ratio (50% B4C and 50% Al2O3). The HSCs fabricated at 1300 rpm, 45 mm/min, and a 50:50% reinforcement ratio exhibited significant necking before failure, leading to a ductile failure mode.