The machinability of materials is highly affected by their hardness, and it affects power consumption, cutting tool life as well as surface quality while machining the component. This work deals with machining of annealed AISI 4340 alloy steel using a coated carbide tool under a dry environment. The microhardness of annealed and non-annealed workpieces was compared and a significant reduction was found in the microhardness of annealed samples. Microstructure examination of the annealed sample revealed the formation of coarse pearlite which indicated a reduction of hardness and improved ductility. A commercially CVD multilayer (TiN/TiCN/Al₂O₃/ZrCN) coated cemented carbide cutting tool was employed for turning quenched and tempered structural AISI 4340 alloy steel by varying machining speed, rate of feed, and depth of cut to evaluate the surface quality, machining forces, flank wear, and chip morphology. According to the findings of experiments, the feed rate possesses a high impact on surface finish, followed by cutting speed. The prominent shape of the serrated saw tooth chip was noticed at a higher cutting speed. Machined surface finish and cutting forces during turning is a function of the wear profile of the coated carbide insert. This study proves that annealing is a low-cost and economical process to enhance the machinability of alloy steel.

The current work investigates the performance of cylindrical‐shaped sintered wick heat pipe at different orientations, numerically. The results are compared and validated with the experimental findings. The study is extended by using a nanofluid (comprising nano‐Curo in deionized water) as a working fluid and the thermal performance of heat pipe with deionized (DI) water has been compared with that of heat pipe with nanofluid (containing various concentrations of CuO nanoparticles in DI water). During the investigation, the nanofluid with 1.0 weight fraction of CuO nanopaticles found to be optimum, which has produced the better results. The numerical analysis has been carried out to study the temperature difference, fluid velocity, and pressure drop of the sintered wick heat pipe using the commercial CFD software, Ansys Fluent R14.5. The computational results are observed to be much closer to the experimental data, and the vapor velocity at the heat pipe’s core has been determined to be 64.54% higher than the liquid flow over the wick structure. Interestingly, the heat pipe pressure drop has been reduced by adding CuO nanoparticles to the working fluid. Finally, the heat pipe loaded with a 1.0% concentration of nano‐CuO in nanofluid has exhibited a notable reduction in pressure drop of 35.33%.

Entropy generation (EG) is intrinsically linked with irreversibilities present within a thermodynamical system, signifying energy losses, mainly in the context of fluid friction and heat transfer. In systems characterized by nanofluid flow, such as those utilized in cooling applications, microelectronics, and heat exchangers, the reduction of EG is essential for augmenting energy efficiency by alleviating these losses. In this communication, mixed convection flow of Sutterby nanoliquid by a porous stretched sheet along with irreversibility is analyzed. The momentum equation is reported by taking mixed convection and magnetic field impacts. Dissipation, Lorentz force, and radiation influences are taken in the development of heat transport relation. The expression for concentration is described by taking the chemical reaction effect. Thermodynamics second law is employed to describe entropy. The partial differential equations (PDEs) indicating the flow phenomenon are altered into self‐similar form via transformations. The NDSolve function of Mathematica package is availed to solve the self‐similar system. The impact of sundry variables on concentration, velocity, Bejan quantity, irreversibility, and thermal field is analyzed graphically. Engineering quantities are discussed numerically. The results reveal that the velocity profile upsurges for higher thermal buoyancy parameter, while it decays for raising magnetic variable. For raising values of Eckert number temperature upsurges, while it decays for an upturn in Prandtl number. Entropy is more for superior values of diffusion and radiation variables.

FSW (friction stir welding) is a solid-state joining method that attracts interest from all industries. The influence of various tool rotational speeds on the microstructure and mechanical characteristics of dissimilar pure Cu-brass joints has been investigated. The travel speed and vertical load were kept constant in the welding trials, at 40 mm/min and 10 kN, respectively, while the tool rotational speed varied from 1000 to 1400 rpm. The increase of the rotational speed to 1400 rpm resulted in degradation of the mechanical properties. The stir zone grain structure was refined; however, the grain size was irregular. Grain refining occurs due to a continuous and discontinuous dynamic recrystallization mechanism. In the grain interior, there were many large dislocations, identifying that incomplete recrystallization took part within the SZ. Instead, the lower rotational speed, i.e., 1000 rpm, led to more uniform grain refinement in the SZ. Moreover, in contrast to the welded zone where very fine grains exist, the base metal and thermomechanically heat-affected zone display coarser grains. Because of the microstructural modification, the stir zone’s mechanical characteristics were higher than the base materials, and the mechanical strength and plasticity were simultaneously upgraded. These results indicate that the size of the grains is independent of rotational speed. And mechanical properties like hardness and impact strength decreased as the rotational speed increased.