钛与铌微合金化Q345C钢显微组织与力学性能的对比Comparison of Microstructure and Mechanical Properties of Ti-Microalloyed and Nb-Microalloyed Q345C Steels

对比研究了钛和铌微合金化Q345C钢的显微组织及力学性能.结果表明:两种试验钢均具有较高的屈服强度、良好的延伸性和低温冲击韧性,钛微合金化钢的延展性和低温冲击韧性更好,强度略低;两种钢的组织均由铁素体和珠光体组成,晶粒度均为9~11级;钛微合金化钢中的夹杂物主要为MnS和少量Ti4C2S2,析出物是尺寸为50~250 nm的TiN,强化机制主要为细晶强化;铌微合金化钢中的夹杂物主要为MnS,析出物是尺寸为20~100 nm的Nb(C,N),强化机制主要为细晶强化和沉淀强化.

The microstructure and mechanical properties of Ti-microalloyed and Nb-microalloyed Q345C steels were studied contrastively.The results show that the two kinds of steels both had high strength,good extensibility and excellent low-temperature impact toughness.Ti-microalloyed Q345C steel had better extensibility and low-temperature impact toughness,but it had lower strength.The microstrure of the Ti-microalloyed steel was similar to that of the Nb-microalloyed steel,both of them were composed of ferrite and pearlite and the grain sizes were 9-11 grade.For the Ti-microalloyed steel,the main inclusions were MnS and a few Ti4C2S2,the precipitation was TiN with sizes of 50-250 nm,and its strengthening mechanism was fine grain strengthening.For the Nb-microalloyed steel,the main inclusion was MnS,the precipitation was Nb(C,N) with sizes of 20-100 nm,and its strengthening mechanism was fine grain strengthening and precipitation strengthening.

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