Prediction of the Transverse-Cracking Tendency for the Continuously-Cast HSLA Steel Slabs

摘要

High-strength low-alloy (HSLA) steel, which contains small amount of niobium, vanadium, and/or titanium, provides better mechanical properties than the plain carbon steel.This benefit comes from the refined microstructure and precipitation strengthening that are achieved by intelligent control of the precipitation reaction of microalloy carbo-nitrides, such as Nb(C,N), TiN, V(C,N), etc. However, such steel is susceptible to transverse cracking during continuous casting. This study is to clarify the relationship among the amount of precipitates, ductility and cracking tendency of HSLA steel slab. The molar fractions of precipitates with various compositions were calculated by ThermoCalc software. The ductility was evaluated by the tensile test conducted on a Gleeble 1500 system. The result shows that a total amount of 0.04at% of AIN, Nb(C,N), and V(C,N) precipitates is a critical value, above which the ductility declines rapidly and the cracking tendency of continuously cast slabs rises correspondingly.