Dilatometry Analysis of Cementite Precipitation in Medium Mn High Carbon Steels
The precipitation and dissolution of cementite in high carbon steels (~1.5 mass % carbon) containing 0,3,and 6 mass %Mn was studied by dilatometry and light optical microscopy.The high carbon concentrations were intended to magnify the length changes associated with the cementite precipitation and dissolution reactions.In the binary Fe-C steel,austenite transformed to cementite and pearlite at cooling rates up to 50 °C/s.In contrast to low carbon steels,decomposition of austenite in the present high carbon steel was not associated with an expansion.In other words,although the austenite to ferrite decomposition leads to an expansion,the formation of a high volume fraction of cementite during the austenite decomposition to a mixture of cementite and ferrite leads to a net contraction.For the alloys containing Mn which had a higher hardenability,pearlite transformation could be avoided by cooling rates applicable in dilatometry but cementite precipitation in austenite still occurred in the cooling step.Delayed pearlite formation in the 3Mn and 6Mn steels allowed to study the length changes associated with the precipitation and dissolution of cementite in the austenite.In spite of the larger atomic volume of cementite compared to that of the austenite,cementite precipitation in the austeniteled to a contraction which could be justified by a reduction in the lattice parameter of austenite as carbon leaves the interstitial sites in austenite.In summary,the potential of dilatometry as a quick method of studying cementite formation and dissolution in medium Mn steels is demonstrated.
medium Mn steels high C steels dilatometry cementite precipitation
MOLA Javad
Institute of Iron and Steel Technology, TU Bergakademie Freiberg, 09599 Freiberg, Germany
国际会议
成都
英文
60-63
2016-11-16（万方平台首次上网日期，不代表论文的发表时间）