A comparison study on microstructure and mechanical property of polygonal ferrite and acicular ferrite pipeline steels
A comparison study on microstructure and mechanical property was made in this work for a commercial polygonal ferrite (PF)dominated pipeline steel and a laboratory developed acicular ferrite (AF)dominated pipeline steel,The tensile test results showed that strength of the AF dominated pipeline steel,reaching the ISO X90 grade pipeline steel,was higher than that of the PF pipeline steel that only met the requirement of API X70 grade pipeline steel.However,the elongation and the Y/T (yield strength/tensile strength)ratio of the two steels were almost the same.The Charpy V-notch impact test results indicated that the AF pipeline steel had higher upper shelf energy (USE)and extremely low energy transition temperature (ETT),about -162℃,much lower than that of the PF pipeline steel,about -121℃.The higher strength of the AF pipeline steel was attributed to its finer grain size and higher dislocation density and sub-boundaries,which could be confirmed from the electron backscatter diffraction (EBSD)analysis,i.e.,smaller effective grain size (EGS)of about 1.32 μm and higher content of low angle grain boundaries (LAGBs)of about 42.6%,than those of the PF pipeline steel.The better toughness of the AF pipeline steel,especially at low temperature,came from its freer EGS and fracture unit,which could also be proved by its more bent crack propagation path.
pipeline steels polygonal ferrite (PF) acicular ferrite (AF) mechanical property electron backscatter diffraction (EBSD)analysis
Wang Wei Shan Yiyin Yang Ke
Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China Graduate School of Chi Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China
国际会议
上海
英文
674-678
2008-09-26（万方平台首次上网日期，不代表论文的发表时间）