Por: CAMILA DE BRITO FERREIRA (GERDAU S/A), Rafael Stella Galdino (GERDAU S/A), Leonardo Contri Campanelli (UNIFESP), Anibal de Andrade Mendes Filho (ufabc), Danieli Aparecida Pereira Reis (UNIFESP)
Resumo:
The application of High Strength Low Alloy (HSLA) steel presents a significant challenge in achieving an optimal balance among mechanical properties, cost-effectiveness, and superior formability. The strategy for alloy design involves the careful adjustment of carbon content alongside the strategic incorporation of microalloying elements such as Nb, V and Ti that provide precipitation hardening and/or solid solution and/or grain refinement. Niobium is the predominant microalloying element, enhancing tensile properties via austenitic grain size regulation during hot rolling, hardness augmentation, and precipitation strengthening through Nb(C,N). The morphology, size and distribution of secondary phases influence on steel behavior. The development of steel should be adequate to promote the best characteristics of selected elements. Through thermomechanical controlled processing (TMCP), the addition of niobium contributes to the improvement of material properties. However, during the continuous rolling for long products, it is necessary to evaluate its effectiveness. The objective of this study was to investigate the influence of niobium (Nb) addition on the grain size, tensile properties, energy absorption during impact testing, and hardness of AISI 4320 steel following a conventional rolling process. The results showed an increase in yield and ultimate tensile strengths.