Review on niobium application in microalloyed steel

With the rapid development of high-strength low-alloy (HSLA) steel, Nb as an important microalloying element has received more and more attention in recent years. The application and behavior of Nb in HSLA steel, including microstructures optimization, refining grain size, and precipitation behavior of Nb-containing phases, were reviewed. Nb could play an important role in following manners: (1) Nb-containing phases promote ferrite formation, and Nb solute promotes bainite formation. (2) Nb solute atoms and Nb-containing phases can inhibit the growth of austenite grains and austenite recrystallization. (3) Nb(C,N) that precipitates in ferrite/bainite can provide more significant strengthening contribution (more than 300 MPa) than that in austenite (about 100 MPa). Some reasonable suggestions for the production of Nb-bearing HSLA steel with excellent mechanical properties were put forward.

Automated summary

This article reviews the application and behavior of Nb in high-strength low-alloy (HSLA) steel, focusing on microstructure optimization, grain refinement, and precipitation behavior of Nb-containing phases. Nb plays an important role in promoting ferrite and bainite formation, inhibiting austenite grain growth and recrystallization, and providing significant strengthening contribution in ferrite/bainite.