热处理工艺对建筑用490 MPa级耐火钢力学性能的影响

Effect of heat treatment technology on the mechanical property of 490 MPa grade fire-resistance steel

研究不同正火温度下 NSFR490 耐火钢的显微组织与力学性能。结果表明,正火处理温度在 730~820 ℃区间内,耐火钢的强度随温度升高而下降,但仍可满足工程应用的标准要求,且塑性得以提高(伸长率由 20%升至 26%)。在 600 ℃进行拉伸试验,结果满足高温屈服强度大于室温屈服强度 2/3 的要求。耐火钢经过 600 ℃高温回火工艺,显微组织整体变化不大,仅晶粒尺寸略有长大,这与耐火钢在高温下的力学性能(屈服强度由 315 MPa降至 292 MPa)表现一致。最后结合该耐火钢的实际工程应用,利用 ANSYS 软件对其进行结构失稳临界温度计算,获得了该材料的位移温度曲线,并得出其失效临界温度点为 620 ℃。

Taking NSFR490 fire-resistant steel as an example, the changes of its metallographic organization and mechanical properties at different normalizing temperatures were studied. The results show that under the normalizing treatment for 730 820 ℃, the strength decreases with the increase of temperature, but it still meets the engineering application standard. Otherwise, the plasticity is improved (elongation rate increased from 20% to 26%). The tensile test at 600 ℃ satisfy the requirement of high temperature yield strength greater than 2/3 of room temperature yield strength. Further observation of the microstructure of NSFR 490 fire-resistant steel shows that the overall microstructure of the alloy has little change under a high temperature process of 600 ℃, and only the grain size has grown slightly, which is consistent with the mechanical properties of refractory steel at high temperature (yield strength decreased from 315 MPa to 292 MPa). At last, combined with the practical engineering application of the refractory steel, the displacement- temperature curve and failure critical temperature point 600 ℃ of the material are obtained by using ANSYS software.