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对马钢生产的耐火H型钢MGFR490B和Q345B H型钢进行了对比试验研究，完成了高温拉伸和高温持久两项力学性能测试和对两种钢微观组织的观察研究。结果表明，耐火H型钢MGFR490B的组织为多边形铁素体﹢珠光体﹢少量贝氏体混合多相组织，此种组织在高温下能保持很好的稳定性，并能在高温下析出合金碳化物，这对降低耐火H型钢MGFR490B的室温屈强比和保持高温屈强比小的波动范围有益。耐火H型钢MGFR490B获得了比Q345B H型钢好的高温强度性能，这与耐火钢的混合多相组织及添加合金元素密不可分。耐火H型钢MGFR490B在600 ℃高温下能保持高的强度，并且其持久断裂时间超过3 h，满足耐火钢的性能指标要求。

In this study,we carried out the comparative experimental study between the fireresistant Hbeam MGFR490B and Q345B Hbeam made in Maanshan steel ,completed two mechanical tests, that is high temperature tensile test and high temperature persistent test, and also microstructure observation of the two steels.The results show that the microstructure of fireresistant Hbeam MGFR490B is mixed multiphase microstructure consisting polygonal ferrite,pearlite and a small amount of bainite,such organization can maintain a good stability at high temperature,and also dissolve out alloy carbides at high temperature,all this is good for reducing the yield ratio of fireresistant Hbeam MGFR490B at room temperature and keep its yield ratio fluctuating in a small scope at high temperature.The fireresistant Hbeam MGFR490B get a better high temperature strength properties than the Q345B Hbeam,which is inseparable of the mixed multiphase microstructure and alloying elements added.The fireresistant Hbeam MGFR490B can keep high strength and its persistent rupture time exceed 3 h,meet the performance requirements of the fireresistant steel.