Effect of Hot Rolling Practice on Microstructure and Mechanical Properties of Fire-resistant Steel

摘要

Trials to develop a C-Mn-Mo-Nb type fire-resistant steel have been carried out by adopting recrystallization rolling (RCR)+air cooling (AC), two-stage rolling (TSR)+AC and RCR+water cooling (WC). Both RCR and TSR followed by AC resulted in polygonal ferrite (F)+pearlite (P) microstructure, while F+bainite (B) microstructure was formed by RCR+WC. The plates with F+P microstructure show tensile strengths ≥490MPa, while those with F+B exhibit tensile strengths ≥590MPa. All the plates show favorable low yield ratios≤0.75, good charpy v-notch impact property >101J at 0℃ and satisfactory high temperature strength (≥2/3 of room temperature yield strength retained at 600℃).