鈦與鈮微合金化Q345C鋼顯微組織與力學(xué)性能的對(duì)比Comparison of Microstructure and Mechanical Properties of Ti-Microalloyed and Nb-Microalloyed Q345C Steels

對(duì)比研究了鈦和鈮微合金化Q345C鋼的顯微組織及力學(xué)性能.結(jié)果表明:兩種試驗(yàn)鋼均具有較高的屈服強(qiáng)度、良好的延伸性和低溫沖擊韌性,鈦微合金化鋼的延展性和低溫沖擊韌性更好,強(qiáng)度略低;兩種鋼的組織均由鐵素體和珠光體組成,晶粒度均為9~11級(jí);鈦微合金化鋼中的夾雜物主要為MnS和少量Ti4C2S2,析出物是尺寸為50~250 nm的TiN,強(qiáng)化機(jī)制主要為細(xì)晶強(qiáng)化;鈮微合金化鋼中的夾雜物主要為MnS,析出物是尺寸為20~100 nm的Nb(C,N),強(qiáng)化機(jī)制主要為細(xì)晶強(qiáng)化和沉淀強(qiáng)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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