Influência da temperatura e do tempo de recozimento nas propriedades mecânicas e microestrutura de um aço microligado ao nióbio para aplicação na indústria automotiva

Abstract

The increasing demand of the automotive industry for functional materials and better superficial quality require steels that meet the higher mechanical properties and quality when cold worked. The trend of the market increasingly points to materials that ensure a good drawability in the production of parts that are being designed more and more with complex formats. On the other hand, the steel industry increasingly works with a lower margin of profitability, requiring the continuous search to improve performance and cost reduction. The present study aims to investigate the influence of the annealing time and temperature processing in the mechanical properties and microstructure of high strength and low alloy steels (HSLA) micro-alloyed niobium and how these vary during the cycle, considering two different process control temperature. For this, two representative curves of the industrial thermal cycle were simulated in samples of the cold rolled steel, examining the changes in the mechanical properties and microstructure of the steel, during the annealing cycle. It was demonstrated that the studied thermal cycle is suitable for the steel, however, it is possible to study the increase in the heating rate and/or the annealing temperature aiming to a better uniformity in the mechanical properties during the annealing cycle and possible reduction in the total time.