Refinement of Steel Austenite Grain Under an Extremely High Degree of Superheating
There thermal cycles for the cyclic heat treatment of a bainitic steel were simulated under the different heating rate ranged from 2 ℃/s to 100 ℃/s and 1000 ℃/s followed by subsequent rapid cooling using a Gleeble3500thermal-mechanical simulator equipped with the self-designed quench system. The microstructural change of the starting material imposed by the different thermal cycles was observed by optical and transmission electron microscope (TEM). The results indicate that a high degree of superheating for the reverse bainitic α→γ transformation was realized as a result of extremely rapid heating (1000 ℃/s) up to an elevated austenitisation temperature (1250℃), which prevent restoration of the initial coarse-grained austenite and lead to a significant refinement of austenite grain. An ultrafine-grained structure with enhanced mechanical properties then formed during the subsequent rapid γ→α reaction on cooling. The results indicate a novel microstructure refinement route for the bainitic steels.
grain refinement cyclic heat treatments phase transformation austenitisation bainitic steel
WANG Q.F. ZHANG C.Y. XU W.W. ZHAO S.J. ZHAO X.Q. YAN Z.S.
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao Technical Center, Tianjin Pipe (Group) Corporation limited, Tianjin 300301, China
国际会议
北京
英文
161-166
2007-09-18（万方平台首次上网日期，不代表论文的发表时间）