摘要
基于控轧控冷工艺研究,在化学成分相同的超低碳微合金管线钢中获得了不同组成比的针状铁素体(AF)复相组织,探讨了其与力学性能的关系。结果表明:①降低终轧温度导致有效晶粒尺寸明显减小,冷却速度和模拟卷取温度的变化对有效晶粒尺寸影响不大;②降低终轧温度,提高冷速,会促进AF复相组织中粒状贝氏体铁素体(GF)、贝氏体铁素体(BF)等低温组织含量的增加,提高模拟卷取温度增强的析出强化效果不如降低终轧温度导致的AF低温组织含量提高和晶粒细化对强度提高的贡献大;③随着终轧温度的下降,大角度晶界含量先提高后降低,在相变点以上40℃附近达到最高值,大角度晶界含量越高,低温韧性越好;④当管线钢获得较高BF和GF含量、低的准多边形铁素体(QF)含量组成的细小AF组织时,综合力学性能优良。
Based on the study of controlled rolling and conrtolled cooling,the acicular ferrite（AF） microstructures with different phase components were obtained in an ultralow-carbon micro-alloyed pipeline steel with the same chemical composition,and the relation between AF microstructures and mechanical properties was investigated.The results showed that：①the effective grain size（EGS） in the steel reduced obviously with decreasing finish rolling temperature（FRT）,but did not change obviously with cooling rate（CR） and simulated coiling temperature（SCT） in the experiment;②Lowering FRT or enhancing CR could increase the percentage of granular bainitic ferrite（GF） and bainitic ferrite（BF） in AF,and the increasing percentage of GF and BF and fine grains make more contribution to the increase of strength than increasing precipitation by enhancing SCT;③The content of high angle grain boundaries increased firstly,then decreased and reached the top at FRT of about 40 ℃ above Ar3.It was found that the higher the fraction of HAGBs was,the better the low temperature toughness was;④When fine AF microstructure was obtained with high GF and BF content and low quasi-polygonal ferrite（QF） content,the pipeline steel could possess good mechnical property.
出处
《焊管》
2009年第11期21-28,31,共9页
Welded Pipe and Tube
关键词
针状铁素体
管线钢
显微组织
力学性能
acicular ferrite
pipeline steel
microstructure
mechanical property
