The carbides precipitation and their evolution at elevated tempering temperature in Crl5Col0Mo5-alloyed heat-resistant bearing steel were investigated by means of the transmission electron microscope.The results show ...The carbides precipitation and their evolution at elevated tempering temperature in Crl5Col0Mo5-alloyed heat-resistant bearing steel were investigated by means of the transmission electron microscope.The results show that there is no carbide precipitated from the martensitic matrix when the sample was tempered at 480℃.However,when the sample was tempered at 540℃,a large number of stable spherical M6C carbides precipitated in the test steel.Nevertheless,there are three types of carbides precipitated from the matrix including M6C,M2C and M23C6 carbides when the tempering temperature reached 600℃.The mechanical properties also present a correlation with the evolution of carbides during tempering at different temperatures.This indicates that the strengthening mechanism of the steel is mainly attributed to the precipitation of carbides and their evolution,including the morphologies and types of carbides at different temperatures.In addition,the austenitic layers with a thickness of about 30 nm have been obtained between the martensite laths after tempering at 600℃.The austenitic layers will produce transformation-induced plasticity effects to improve the toughness of the steel.展开更多
The effect of heat treatment and deep cryogenic treatment on microstructural evolution of low carbon martensitic bearing steel was investigated.The experimental results showed that the lath martensite was obtained by ...The effect of heat treatment and deep cryogenic treatment on microstructural evolution of low carbon martensitic bearing steel was investigated.The experimental results showed that the lath martensite was obtained by quenching and a few twins as substructures formed in some martensitic laths.The rudiment of sub-interfaces of martensitic lath was formed in the highdensity dislocation regions after deep cryogenic treatment;meanwhile,the number of twins increased,especially in the highdensity dislocation regions.This phenomenon is due to the increase in internal stress caused by cryogenic treatment.After tempering,the rudiment of sub-interface further evolved into the martensitic lath boundary,and thus the original martensitic laths were refined.The twins formed by cryogenic treatment did not disappear after tempering.In addition,small quantities of annealing twins formed in tempering process.Martensitic laths morphology and substructures in different stages of the heat and deep cryogenic treatment were observed by tninsmission electron microscopy.展开更多
基金The work was financially supported by National Natural Science Foundation of China(Grant No.51761022)Fund for Testing and Analyzing of Kunming University of Science and Technology(Grant Nos.2016T20110167 and 2017M20162130021).
文摘The carbides precipitation and their evolution at elevated tempering temperature in Crl5Col0Mo5-alloyed heat-resistant bearing steel were investigated by means of the transmission electron microscope.The results show that there is no carbide precipitated from the martensitic matrix when the sample was tempered at 480℃.However,when the sample was tempered at 540℃,a large number of stable spherical M6C carbides precipitated in the test steel.Nevertheless,there are three types of carbides precipitated from the matrix including M6C,M2C and M23C6 carbides when the tempering temperature reached 600℃.The mechanical properties also present a correlation with the evolution of carbides during tempering at different temperatures.This indicates that the strengthening mechanism of the steel is mainly attributed to the precipitation of carbides and their evolution,including the morphologies and types of carbides at different temperatures.In addition,the austenitic layers with a thickness of about 30 nm have been obtained between the martensite laths after tempering at 600℃.The austenitic layers will produce transformation-induced plasticity effects to improve the toughness of the steel.
基金Funding was provided by Analysis and Testing Foundation of Kunming University of Science and Technology(Grant Nos.2017M20152230037,2017M20152230069).
文摘The effect of heat treatment and deep cryogenic treatment on microstructural evolution of low carbon martensitic bearing steel was investigated.The experimental results showed that the lath martensite was obtained by quenching and a few twins as substructures formed in some martensitic laths.The rudiment of sub-interfaces of martensitic lath was formed in the highdensity dislocation regions after deep cryogenic treatment;meanwhile,the number of twins increased,especially in the highdensity dislocation regions.This phenomenon is due to the increase in internal stress caused by cryogenic treatment.After tempering,the rudiment of sub-interface further evolved into the martensitic lath boundary,and thus the original martensitic laths were refined.The twins formed by cryogenic treatment did not disappear after tempering.In addition,small quantities of annealing twins formed in tempering process.Martensitic laths morphology and substructures in different stages of the heat and deep cryogenic treatment were observed by tninsmission electron microscopy.
