Effects of States of Carbon and Solute Nitrogen on Toughness of Ferritic Steel

To develop microstructure control concepts for ensuring the toughness of high-strength steel plates, basic research was conducted using ferrite single-phase steels with different amounts C, and effects states C were investigated along those solute N. In this study, Fe-0.017C (mass%) alloy, wherein state changed to a solid solution, intragranular cementite, intergranular used microstructural observation, Charpy testing, fracture surface investigation. The results reveal that cementite best, followed by steel. significantly inferior toughness, coarse leads dislocation pile-up, initial crack formation, macroscopic brittle fracture. caused deformation twins. It is thought fine only had minor effect on initiation mobility. Twin also confirmed at point in Hence, it deduced deterioration resulted from promotion twinning, which replaced movements. However, smaller compared N, partly This attributed suppression presence small amount C.