DECOMPOSITION OF SUPERCOOLED AUSTENITE IN CONTINUOUS COOLING TRANSFORMATION PROCESS OF A Mn-Mo-Ni LOW ALLOY STEEL
Decomposition of supercooled austenite in continuous cooling transformation process of a Mn-Mo-Ni low alloy steel was evaluated by dilatometric measurements,light microscopy,electron backscatter diffraction,and microhardness testing and other methods.The results show that at the cooling rates of 1°C/s or below,ferrite initially formed and continuously rejecting C into the untransformed austenite,which transforms to C-rich lower bainite at lower temperature,resulting in ferrite-bainite dual-phase microstructures.At the cooling rates between 1 °C/s and 5 °C/s,the successive transformation products are bainite ferrite,upper bainite and lower bainite,and islands of carbon-enriched austenite transform to martensite(plus retained austenite)at low temperatures.The upper bainite and martensite dual-phase microstructures are formed at the range of 5 °C/s to 50 °C/s with a lower Ms.When cooling rates greater than approximately 50 °C/s,the microstructure are martensite and retained austenite at room temperature.With the increase of cooling speed,the residual austenite content increased before decreased at the cooling speed of 2 °C/s,which is probably associated with the incompleteness of bainite transformation.
Mn-Mo-Ni low alloy steel Austenite decomposition hardness
C.W.Li L.Z.Han Q.D.Liu X.G.Tao J.F.Gu W.M.Zhang
Institute of Materials Modification and Modeling,School of Materials Science and Engineering,Shanghai Jiao Tong University,800 Dong Chuan Road,Shanghai,200240,PR China
国内会议
杭州
英文
151-157
2015-11-11（万方平台首次上网日期，不代表论文的发表时间）