Abstract: The test super-high strength weathering steel (/%: 0. 062 〜0. 065C, 0. 29 〜0. 30Si, 1. 23 ~ 1. 27Mn, 0. 49 -0. 52Cr, 0. 19 -0. 20Ni, 0. 29 ~0. 31 Cu, 0 ~0. 20Mo, 0. 035 ~0. 060Nb) is melted by a 50 kg vacuum induction furnace, forged to 60 mm x 60 mm billet, then hot rolled to 4 mm plate in laboratory by finishing rolling pass at 880℃ ， water cooling to 600℃ ，furnace cooling. The effect of Nb and Nb-Mo microalloying on structure and mechanical properties of steel are studied by optical, scanning electron and transmission electron microscope, and universal tensile test machine. Test results show that as compared with 0. 035% Nb steel the grain size of 0. 060% Nb steel is finer, the strength increases by ~70 MPa, but the elongation is the same as that of 0. 035Nb steel as compared with non-added Mo steel (0. 035Nb steel and 0. 060% Nb steel) the M/A phases in 0. 035% Nb-O. 20% Mo steel increase obviously and bainite structure occurs in steel led to increase of tensile strength and decrease of yield-strength ratio and elongation of steel.

摘要： 试验超高强耐候钢(/%:0.062～0.065C、0.29～0.30Si、1.23～1.27Mn、0.49～0.52Cr、0.19～0.20Ni、0.29～0.31Cu、0～0.20Mo、0.035～0.060Nb)由50kg真空感应炉熔炼,在实验室锻成60mm×60 mm方坯并热轧成4 mm板材,末道次温度880℃,水冷至600℃炉冷。用光学显微镜、扫描电镜、透射电镜和万能拉伸试验机研究了Nb和Nb-Mo微合金化对该钢组织和力学性能的影响。试验结果表明,0.060%Nb钢较0.035%Nb钢晶粒更细,强度提高～70 MPa,但伸长率相同;与未加Mo的0.035%Nb和0.060%Nb钢相比,0.035%Nb-O.20%Mo钢M/A相明显增加,并出现大量贝氏体组织,抗拉强度增加,但屈强比和伸长率降低。

关键词: Nb微合金化, 超高强耐候钢, 组织, 力学性能, 析出相