EFFECT OF AUSTENITE DEFORMATION AND CONTINUOUS COOLING ON MICROSTRUCTURE EVOLUTION IN A PIPELINE STEEL
The effect of austenite deformation and continuous cooling on the evolution of microstructure in a high temperature processing(HTP)concept pipeline steel was investigated in this research.It was found that without austenite deformation,the transformed microstructure consists of blocky quasi-polygonal ferrite(QF)grains and parallel bainitic ferrite(BF)laths at a cooling rate of 0.5 °C/s.With increased cooling rates,the fraction of BF laths is raised and the microstructure reaches full BF at cooling rates of 5°C/s and higher.After austenite deformation,BF laths disappear at low cooling rates of 0.5~1°C/s and QF is the dominant phase.At a higher cooling rate of 5°C/s,the fraction of QF is reduced and acicualr ferrite(AF)becomes the main phase surrounded by QF grains.Increasing the cooling rate further,QF disappears and fthe raction of BF rises,finally leading to a BF dominant microstructure at a cooling rate of 50°C/s.Factors influencing these microstructure evolution characteristics were discussed,including segregation of niobium atoms at austenite grain boundary and the introduction of intragranular nucleation sites by deformation.
HTP pipeline steels Phase transformation Cooling rate Austenite deformation
H Zhao JM Gray EJ Palmiere
Department of Materials Science and Engineering,The University of Sheffield,Sir Robert Hadfield Buil Microalloyed Steel Institute,5100 Westheimer Road,Houston,Texas 77056,USA
国内会议
杭州
英文
775-781
2015-11-11（万方平台首次上网日期，不代表论文的发表时间）