摘要
The effect of microstructures on strength,strain capacity and low temperature toughness of a micro-alloyed pipeline steel was elucidated.Five various dual-phase microstructures,namely,acicular ferrite and a small amount of(around 2 vol.%)polygonal ferrite(AF+PF),polygonal ferrite and bainite(PF+B),polygonal ferrite and martensite/austenite islands(PF+M/A),polygonal ferrite and martensite(PF+M)and elongated polygonal ferrite and martensite(ePF+M),have been studied.Experimental results show that AF+PF microstructure has high yield strength and excellent low temperature toughness,whereas its yield ratio is the highest.Polygonal ferrite-based dual-phase steels,PF+B,PF+M/A and PF+M microstructures show better strain capacity and low temperature toughness.The strain capacity and low temperature toughness of ePF+M microstructure are the worst due to its high strength.The relationship between microstructure,strength,strain capacity and toughness has been established.Based on the results,the optimum microstructure for a better combination of strength,strain capacity and toughness is suggested to be the one having appropriate polygonal ferrite as second phase in an acicular ferrite matrix.
基金
financially supported by the National Key Research and Development Program of China(Grant Nos.2017YFB0304901,2018YFC0310302 and 2018YFC0310304)
State Key Laboratory of Metal Material for Marine Equipment and Application Funding(Grant No.SKLMEA-K201901)
the Doctoral Scientific Research Foundation of Liaoning Province(Grant No.20180540083).
