This work investigates the microstructure evolution during the rotary friction welding (RFW) of Inconel 718 alloy. A cellular automata (CA) approach is implemented to evaluate a cylindrical component (at weld center and edge wall), predicting dynamic recrystallization (DRX) and grain size of friction welds. The input variables for RFW were rotational speed (500, 1000, and 1200 rpm), feed rate (2 mm/s), and feed distance (3.6 mm). The CA model is based on the Laasraoui-Jonas model and explains intricate grain transformation in terms of microstructure, temperature, strain, and strain rate. Calculated grain consists of very fine grain structure at the stir zone followed by the thermo-mechanical affected zone, where partial recrystallized microstructure was present. The average grain size was 2.5 µm, which is comparable to reported experimental values. The grain analysis revealed that temperature and strain are most affecting factors to attain a refined microstructure. The strain rates predicted for both center and edge locations of the weld were found to be higher as rotational speed increased. A steady strain distribution is noted at greater temperature for all the rotational speeds. The results of this work contribute toward the understanding of microstructure and mechanical response for RFW of Inconel 718.

In this work, different processing routes were investigated to evaluate the effects of hot rolling temperature, annealing before cold rolling (ABCR), and one- or two-stage cold rolling and annealing schedules to obtain more efficient electrical steels. The correlation between processing variables, microstructure, thickness, and magnetic properties was established from the analysis of 3D surface plots. It was found that the lowest core loss values (3.4 W/kg) were obtained when steel is processed by hot rolling (800 °C), ABCR (880 °C–180 min), first cold rolling (up to 0.25 mm), first annealing (850 °C–10 min), second cold rolling (up to 0.2 mm), and second annealing (850 °C–10 min). The better combination between thickness and grain size leads to the enhancement of the magnetic properties, which affects the way eddy and hysteresis losses contribute to the total core losses.