Caracterização e comparação microestrutural de regiões com diferentes tempos locais de solidificação em aço ferramenta para trabalho a frio

Abstract

Cold work tool steels are materials widely used in industrial processes due to their high wear resistance, toughness, and dimensional stability. This study aimed to investigate the microstructural condition of the VF800AT® tool steel in its as-cast state, focusing on the influence of local solidification time on the morphology, size, and distribution of carbides. To achieve this objective, thermodynamic calculations computational simulations were conducted using the Thermo-Calc® and ProCAST® software, along with experimental analyses, including microstructural characterization through optical microscopy and carbide quantification using the ImageJ® software. The results confirmed that the local solidification time directly influences the distribution and size of carbides. Samples taken near the bottom of the ingot, characterized by shorter solidification times, exhibited smaller and more uniformly distributed carbides. Conversely, samples located near the top of the ingot, where solidification time was longer, displayed larger and more segregated carbides, aligning with theoretical expectations. However, one sample presented divergent results, showing an absence of large and segregated carbides, raising hypotheses about statistical coincidences, unidentified metallurgical phenomena, or three-dimensional variations in the microstructure. Thus, this study reinforces the importance of controlling solidification time in the production of tool steels, highlighting its influence on microstructural homogeneity and, consequently, on the material's mechanical properties. The findings also suggest the need for further investigations to better understand the observed particularities, contributing to advancements in the processing and development of high-performance metallic alloys.