Abstract: The mechanical properties, structure and precipitates of medium plate 30 mm X 2 500 mm of Ti micro alloyed Q345D steel (/%: 0. 15C, 0.27Si, 1. 36Mn, 0. 019Ti, 0. 011P, 0. 003S, 0. 026Als) produced by hot metal desulphurizing-150 t converter-RH-shielding casting-control rolling and cooling process have been studied. Results show that of Ti microalloying Q345D steel the tensile strength is m525 MPa, yield strength N390 MPa, elongation >29% and the -40 ℃. impact energy is 125 J; the structure of steel consists of pearlite, ferrite and minor sorbite with grain size grade 12~14； the main inclusions in steel are MnS and Ti₄C₂S₂, the precipitates in steel are dispersive-distributed 50 ~250 nm TiN; and the increment of strength of steel is mainly caused by fine-grain strengthening of TiN.

摘要： 研究了铁水脱硫处理-150 t转炉-RH-保护浇铸-控轧控冷工艺生产的Ti微合金化Q345D钢(/%:0.15C,0.27Si,1.36Mn,0.019Ti,0.011P,0.003S,0.026Als)30 mm×2500 mm中板的力学性能、组织和析出物。结果表明,Ti微合金化Q345D钢的抗拉强度≥525 MPa,屈服强度≥390 MPa,延伸率≥29%, -40℃冲击功125 J;该钢组织为珠光体+铁素体+少量索氏体,晶粒度为12~14级;钢中夹杂物主要为MnS和Ti₄C₂S₂,钢中析出物为50~250 nm弥散分布的TiN;钢的强度增加主要是TiN细晶强化作用引起的。

关键词: Q345D钢 , 中厚板, Ti微合金化, TiN析出物 , 细晶强化