Evaluation of abrasive wear resistance and microstructural analysis of the UTP 7200D electrode through the SMAW welding process

Abstract

As a result of technological advancement in the metalworking industry, as well as to contribute to its scientific field, this article presents a study on the mechanical behaviors of the UTP 7200D welding electrode. More specifically, it aims to understand the behavior of this material in relation to abrasive wear and its metallographic structure. Welding processes represent a challenge due to the wide variety of available alloys and are widely used in metallurgical industries for joining materials and adding an extra coating layer to improve performance. In this process, a less resistant core material is covered by a material with superior properties, establishing gains in the cost-benefit ratio. Knowledge of the tribological characteristics of materials subject to abrasive wear is fundamental for the optimization and definition of machine elements, and it is a determining factor in quantifying the useful life of mechanical devices. In this article, the abrasive wear resistance properties of the coating deposited by the UTP 7200D welding electrode (on an SAE 1020 steel substrate) were evaluated, and its metallographic structure was studied. This electrode is usually indicated for services where the properties of austenitic manganese steel are required under conditions of high impact, compression, friction, and moderate abrasion, providing high resistance to cracking. The samples were subjected to a wear test using a rubber wheel abrasometer, standardized by ASTM G65-91, and the mass loss values were obtained. The mechanical properties of a material are related to its microstructure, making it very important to understand them qualitatively by evaluating its microstructural behavior and chemical composition in different zones. This involves assessing the constitution and structure of metals to relate them to mechanical properties and manufacturing processes. This structure reveals the aggregates and phases of a metallic alloy as a function of its chemical composition or the transformation processes applied to it. From the results obtained, it was possible to state that the UTP 7200D electrode did not have adequate abrasive wear resistance for coating applications. The deposited material had an average loss of 2.92 grams, whereas, when compared with the literature, a metal used as a crusher with a tungsten carbide coating loses around 0.4 grams in the same time applied to both cases. However, for the microstructural evaluation, the welded region showed dendrites that form when the material solidifies in motion, a phenomenon that characterizes a complex solidification process with this electrode. In the region of the boundary between the base metal and the deposited metal, it is possible to perceive Widmanstätten ferrite. This type of ferrite is characteristic of welding with supercooling and has a higher hardness compared to polygonal ferrite, which is not always desirable due to the increased fragility of the heat-affected zone