材料期刊网

根据微合金纳米第二相在加热升温过程中的析出特点，充分发挥微合金第二相的强化作用,提出了遇火强化型耐火钢技术新思路。与传统耐火钢相比，通过降低钼含量,可以降低钢材成本。遇火强化型耐火钢的生产工艺路径为热轧＋快速冷却，抑制微合金纳米第二相在热轧板冷却过程中析出的同时，获得中低温转变组织。工业试制Nb-V-Ti-Mo复合微合金化遇火强化型耐火钢Q420FRE组织类型为细小的粒状贝氏体，力学性能满足耐火钢标准GB/T 28415-2012的要求，其中室温伸长率和-40℃低温冲击韧性优异。经计算，工业试制的遇火强化型耐火钢Q420FRE在600～700℃下的纳米MC相沉淀强化增量超过50 MPa。模拟测试表明，工业试制Q420FRE的耐火极限温度接近650℃，600℃高温回火3 h不失效，空冷至室温后屈服强度上升，具有二次耐火性。

According to the precipitation characteristics of the nano-sized microalloying second phase during the heating process, a new technical idea of fire induced strengthening fire-resistant steel which was strengthened by precipitation par-ticles at high temperature was proposed. The content of Mo addition can be reduced compared with the traditional fire-re-sistant steel. The production method to match the fire induced strengthening fire-resistant steel was accelerated cooling fol-lowing hot rolling, which inhibited the precipitation of microalloying second phase during cooling after hot rolling and ob-tained low-temperature transformation product. Nb-V-Ti-Mo complex microalloying of fire induced strengthening Q420FRE fire-resistant steel by industrial trial had a microstructure of fine granular bainite. The mechanical properties of industrial trial Q420FRE has reached the requirements of the standard GB/T 28415-2012. Especially, the elongation at room temperature and the low-temperature impact toughness at-40℃ were quite excellent. Furthermore, the increment of nano-sized MC phase precipitation hardening between 600~700℃was estimated over 50 MPa in the industrial trial fire induced strengthening Q420FRE fire-resistant steel plates. Simulation tests show that the fire-resistant temperature of industrial trial Q420FRE was close to 650℃. After tempering within 3 h at 600℃, the industrial trial Q420FRE did not fail. After air cooling, the industrial trial Q420FRE had higher yield strength at room temperature and a secondary fire re-sistance.