Effects of slight amount Nb on mechanical properties of Ti microalloyed high strength heavy steel plates

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• 作者：ZHAO SixinYAO Liandeng
• 会议时间：2013-06-01
• 关键词：high strength heavy steel plate ; Nb-Ti precipitates ; mechanical property
• 作者单位：Research Institute , Baoshan Iron & Steel Co.,Ltd.,Shanghai 201900,China
• 母体文献：第五届宝钢学术年会论文集
• 会议名称：第五届宝钢学术年会
• 会议地点：上海
• 主办单位：中国金属学会
• 语种：chi

摘要

Microstructures of 0.08% C-O.09Ti% and 0.08% C-O.025Nb% -0.09Ti% high strength heavy plates produced by TMCP are composed by banitic ferrite plates and martensite-austenite ( MA) constitutes locating at plates boundaries.After tempering process,MA decomposed and carbides precipitated as well as boundaries of bainitic ferrite plates became weaken.The amount of MA was found increasing in Nb adding steels.TiCN、 Ti4C2S2 were found in Ti microalloying steels.Coarsen Nb-Ti complex precipitations (1~2μm) were found in Nb adding steel.The yield strength,tensile strength and Charpy impact energy decrease with Nb addition at TMCP processes.However,the difference of mechanical properties of Nb-Ti and Ti microalloying steel plates is small after tempering process.Steel plate with optimized strength and toughness was obtain by finish cooling at 500℃ following by temper at 550℃.Solution Nb in austenite is 0.01% at experimental austenitize temperature.It is reasonably that the mechanical properties decreasing of Nb-Ti steel relate to the pinning effect of coarsen Nb-Ti precipitates to mobile dislocation and boundaries is lower than that of the fine precipitates in Ti microallying steel.