Experiment And Research On Work-hardening Mechanics Of Wear-resistant High Manganese Steel

Rail-switches are key parts of rail structure. High manganese steel frog is the reasonable choice on most railways in our country. The domestic and foreign scholars have carried out the extensive research about the reason of the high-manganese steel's exceptionally high work-hardening ability, but have not yet arrived at a unified and comprehensive conclusion until now.The high-manganese steel samples are processed with full work pre-hardening by using the asynchronous rolling technology. Through the metallographic microscope, the microstructure and the organization evolvement of the high-manganese steel samples are observed, analyzed and compared with the traditional processing craft and the conventional rolling. Using the electron ray diffraction the phase analysis, the demarcation of the crystal structure and the confirmation of the lattice parameter of the samples are carried on. Through the high resolution transmission electron microscope, the dislocations, the twin crystals and their distribution are observed. The results are analyzed through the above experiments based on the research in the high-manganese steel wear-resisting performance, and confirmed the rationalities of the deformation induction martensite stiffens theory, the twin crystals hardening theory, the dislocation hardening theory, the fault hardening theory and so on.The research indicates that the high-manganese steel under the working conditions is the face-centered cubic austenite, the {111} surface is its main slip plane, <111> is the main direction of slip, the slip systems are of many kinds. Therefore, the high-manganese steel has the very good plasticity and toughness. Under the asynchronous rolling, the high-manganese steel's typical organization shows that the straight distortion belt as well as the twin distortion start to present at the small deformation, and the dislocation configuration exhibits for the straight banding. Along with deformation quantity's augmentation, the twin crystals quantity increases and the twin crystals density increases obviously. Through the deformation overlapping twin crystals mutually turn into cross twin crystals, where has the kink. After the deformation quantity achieves the certain extent, twin crystals quantity increasing rate tends to slow, and a few secondary twin crystals present in the twin crystals. Simultaneously, the distorted belt brought bending or the slipping stair, the crystal grain have the serious distortion even to break the refinement in the organization. Grain refining presents the massive high density dislocation tangle and the deformation twin crystals.It is discovered in the research that after the high-manganese steel samples are rolled through the different deformation rates, the grain size may refine to a nanometer magnitude. The high-manganese steel surface nanometer mechanism has the relation to the high density dislocation tangle, the high density dislocation response and reorganization, and the multiple twin crystals cut mutually as well as the interactivity of the twin crystals and the dislocation. This research has the very beneficial role to study the high-manganese steel to enhance its resistance to wear and has the important theoretical significance and the value in practice.