# Investigating the Welding Parameters in Friction Stir Welding of Yellow Brass 405-20
## 1 Introduction
(2019) found the numerical effect of an eccentric cylindrical pin on heat development during FSW. Though thermal simulation was in good agreement with that of the experimental work, the same approach may be used for brass to see whether there still exists a good agreement between numerical and empirical results. Brass is an alloy of copper and zinc. Brass properties are determined from the careful configuration of the percentage of copper and percentage of zinc. It is widely used as an engineering and industrial material due to its various striking properties, such as high strength, high corrosion resistance, and high electrical and thermal conductivities. Brass may easily be formed when processing and it is nice looking before and after processing. Brass presents difficulties when it is subjected to fusion welding since the melting of brass usually involves the evaporation of zinc. Hence, novel joining processes should be employed which do not cause melting and the brass remains in its solid state during and after welding. FSW may be used to weld brass, keeping in mind that brass must not be melted. Only one research paper was found in the past five years on the FSW of brass, showing the very limited research efforts towards joining brass, and it could become part of a great body of literature on FSW over the last decade. For example, [PERSON] et al. (2019) successfully welded 2 mm-thick brass plates using FSW subjected to rapid cooling. When comparing the improvements in the yield strength and the UTS for conventional FSW, the rapidly cooled FSW showed an improvement of up to 31 and 24%, respectively. Although a group of researchers has finally broken the non-welding silence on brass, no numerical efforts are evident focusing on the FSW of brass as a solid function of FSW factors. [PERSON] et al. (2019) reported the formation of defects in their study on the microstructure of 63/37 brass. They employed an optical microscope, scanning electron microscope (SEM), and scanning transmission electron microscope (STEM) to study the microstructure of brass under investigation. It was revealed that the alpha grains resulted in dynamic recrystallization (DR) after FSW. However, the beta phase split between the alpha grains without DR. [PERSON] et al. (2019) joined AA6061-T6 aluminum sheets of 0.8 mm thickness using high-speed FSW with rotational speed equal to 8000 rev/min and welding speeds of 300-1200 mm/min. Grain refinement was achieved under these levels of FSWFs settings, as compared to the conventional FSW. However, Mg\({}_{2}\)Si, Al\({}_{8}\)Fe\({}_{2}\)Si, and Al\({}_{2}\)CuMg precipitated and re-precipitated in the weld nugget, resulting in lessening the weld softening and brittle fracture of welded joints. Although researchers have made their best efforts to reveal various phenomena that are happening at the weld zone, a thorough understanding of microstructural phenomena has not been extensively revealed for brass materials. From the literature review, it is quite evident that very few researchers have currently focused on welding brass via FSW. Researchers have looked at FSW using various materials and process parameters. They have done substantial numerical and empirical studies. Manynumerical studies were experimentally validated for various materials other than brass. Most of the researchers used non-standardized samples too. Temperature distributions during welding and their predictions through numerical studies are extremely important, since these give both excellent indications of the effect of FSW weld factors on the thermal changes and assurance of temperature reach, i.e., it must remain below the melting point of the material under consideration. In this context, researchers have already validated temperatures via k-type thermocouples. Therefore, the aim of this study was to perform numerical studies for FSW of brass with their proper validation for thermal distribution at HAZ using a thermal imager that is more reliable than k-type thermocouples.