International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

It is well known that there are several ways to make a butt weld depending on the thickness of the plates to be welded. This paper shows how important it is to prepare the surfaces to be joined by welding. In this paper, the 15 mm thick plates, made of mild steel S235JR, were welded face-to-face with a K-weld using the MIG welding method. The preparation of the plates before welding was not satisfactory, according to empirical instructions, and the resulting weld has defects. Four plates were welded face to face, resulting in two welds. The welds cooled in different ways after welding, one was cooled more slowly in air, and the other was cooled more quickly in water. After welding and cooling the welds, a metallographic analysis of the microstructures of the welds was carried out, and then their hardness was measured using the Vickers method. The conducted metallographic tests concluded that the heat-affected zone has a fine-grained structure, and the melting zone has a cast structure. After the hardness measurement, it can be seen that the hardness values in both the melting zone and the heat-affected zone increase from the root to the surface of the weld. Finally, a strength calculation was performed to determine how much static and dynamic alternating force the realized welded K-joint can withstand compared to the ideal value with good surface preparation

Plasma arc cutting is a non-conventional manufacturing process that has potential for modern day metal cutting demands with good dimensional accuracy and high-quality surfaces without any extra operation. In this experimental study, AISI 304, AISI 430 and EN S235JR sheet materials having 5 mm. thicknesses, has cut with plasma arc cutting. Each material has cut with 6 different variations. Current, cutting speed, arc voltage, gas pressure and gas flow rate have been changed as process parameters. The quality of the cut has been monitored by measuring the edge roughness, the hardness of the heat-affected zone (HAZ) and the results has compared.