Abstract: The precipitating behavior of secondary phases bearing Nb, Ti and Cu in high performance bridge steel (% ： 0.07C, 1.52Mn, 0. 17Si, 0.003S, 0.013P, 0. 30Cr, 0.40Ni, 0. 68Cu, 0. 19Mo, 0.01V, 0.01Ti, 0.04NE) in two stage control rolling and cooling process (1 006 ~979℃ and 813 ~782 °C ) from 250 mm casting slab to 30 mm plate and in tempering at 600 °C has been studied. Results show that there are precipitates of secondary phases during all control rolling and cooling process and later tempering process: in higher temperature roiling zone the ≥50 nm cubic TiC particles are first precipitating, in flowing deformation process the 10-25 nm NbC particles precipitate； during tempering process the NbC particles nucleate attached to TiC particles and grow up, besides, the 3 ~ 30 nm Cu dispersed precipitates are observed.

Key words: Bridge Steel, Control Rolling and Cooling, Tempering, Precipitates of Secondary Phases

摘要： 研究了高性能桥梁钢(%:0.07C、1.52Mn、0.17Si、0.003S、0.013P、0.30Cr、0.40Ni、0.68Cu、0.19Mo、0.01V、0.01Ti、0.04Nb)250 mm铸坯在二段控轧控冷(1 006～979℃和813～782℃)至30 mm板和600℃回火过程中含Nb、Ti和Cu第二相的析出行为。结果表明,在控轧控冷及随后的回火过程中均有第二相析出:在高温轧制区,≥50 nm立方形的TiC首先析出,随后的变形过程中,10～25 nm NbC析出;在回火过程中NbC依附于TiC形核长大,同时也观察到3～30 nm Cu弥散析出。

关键词: 桥梁钢, 控轧控冷, 回火, 第二相析出