STRUCTURE AND PHASE COMPOSITION BEHAVIOR IN MULTICYCLE FATIQUE OF QUENCHED CARBON STEEL
The defect substructure and phase composition evolution of quenched 60GS2 (0,6％C,1％Mn,2％Si) steel are studied by transmission diffraction electron microscopy.Quenching the steel leads to the formation of a mixed packet-plate martensite structure containing around 8-10％ residual austenite.The mean transverse dimensions of the plate and packet martensite crystals are 242±11 nm and 180±10 nm,respectively. Fatigue loading of steel with N1= 1,2·105 cycles leads to the formation of subgrains,whose relative content is around 44％.The mean size of the anisotropic subgrains is 1,150±0,025 μn.Increasing the number of loading cycles to N2= 1,46·105 (failure) increases the subgrain content to around 75％ and increases their mean size to 1,70±0,03 μn.Within the subgrains,there is a tangled-network dislocational structure.The scalar dislocation density is 2,8·10cm-2.Cementite particles are distributed along the subgrain boundaries and at their junctions,as a rule.At the intermediate stage of loading,the cementite particles take the form of layers,while the failured sample tends to have globular morphology. In the intermediate stage of fatigue loading N1 displacement of the large-angle grain boundaries is observed,indicating dynamic recrystallization of the material.This process is accompanied by the formation of regions characterized by high elastic stress fields and a large quantity of cementite particles at the boundary junctions.Increasing the number of loading cycles to around 1,46·105 is accompanied by further tempering of these volumes of the material,with the formation of a two-phase martensite-austenite structure.Repeated martensitic transformation is sometimes also observed in inhomogeneous packets.In this case,the newly formed martensite crystals lie parallel to the initial martensite crystals.
carbon steel martensite fatigue
V.E.Gromov O.V.Sosnin Yu.F.Ivanov E.V.Kozlov
Doctor of Physics and Mathematics,Professors,Siberian State University of Industry,654007,Russia,Nov Doctor of Physics and Mathematics,Professors,Siberian State University of Industry,654007,Russia,Nov
国际会议
第二届国际非均质材料力学会议(The Second International Conference on Heterogeneous Material Mechanics)
安徽黄山
英文
434
2008-06-03（万方平台首次上网日期，不代表论文的发表时间）