The effect of Nb on microstructure, mechanical, and corrosion behavior of low Mn, microalloyed δ‐TRIP steel; a comparative study

摘要

>The aim of the present study was to examine the feasibility of achieving a better combination of yield strength, ductility, and corrosion resistance of δ‐TRIP steel through the concept of microalloying. Three δ‐TRIP steels with different contents of Nb (0, 0.025, 0.076?wt%) were subjected to the microstructural, mechanical, and electrochemical examination. ASTM A283 and ASTM A516 steels were taken as comparative samples. The obtained results revealed a threefold increase in strength?×?ductility products of TRIP steels (35?255?MPa%) than comparative samples (12?760?MPa%) due to the TRIP effect and multiphase nature of the TRIP steel. The addition of Nb to the TRIP steel led to an unexpected decrease in the ultimate strength (from 1167 to 955?MPa) but an increase in ductility (from 30.21 to 31.78%) and corrosion resistance. The results of the electrochemical measurements showed that while A516 alloy exhibited the lowest corrosion resistance, the corrosion resistance of TRIP specimens was significantly increased by the addition of Nb which resulted in enhancement of the charge transfer resistance of the steel and indicates the superior corrosion resistance of the steel with 0.076% Nb.