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Investigations of the Modification and Aging Treatment of High Manganese Steel

Author: LiLiang
Tutor: XuXiaoZuo
School: Central South University
Course: Materials Science and Engineering
Keywords: high-manganese steel modification microstructure crystalstructure wear
CLC: TG142.1
Type: Master's thesis
Year: 2013
Downloads: 46
Quote: 0
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Abstract


Much attention has been paid to high manganese austenitic steel since it was invented, the organization is stable single austenite after quenching. In the condition of high-stress, high manganese steel has very good abrasion resistance, because of dislocation hardening, transformation hardening and deformation twin sclerosis, work hardening will occur on the surface of high manganese steel. But under the strong impact load, high manganese is not fully work hardening. Shear failure is very easily occurred on the surface of high manganese steel, which affect the wear resistance. In this paper, High manganese steel with rare earth-low melting point alloy modification, then by aging treatment, the influence of modification on the organization and properties have been studied, and aging precipitation behavior of rare earth-low melting point alloy Modified High manganese steel and Its Influences on Mechanical Properties also researched in this paper. The results are summarized as follows:(1)After rare earth-low melting point modification, the austenite grain of as-cast high manganese steel was obviously refinement., and carbide transform thick needle into ball; After water toughening treatment, the grains of metamorphic high manganese steel are smaller than ordinary high manganese steel, and the original hardness of high manganese steel ascend197HBS from215HBS, tensile strength increases from758.6MPa to845.9MPa, abrasion loss reduced from1.7077g to1.2237g. The result shows that rare earth-low melting point modification treatment improved the organization of manganese steel, and proved the comprehensive performance of the high manganese steel.(2)After1hour aging at460℃for modified high manganese steel, the ball precipitate down the austenitic grain precipitation, with the extension of aging time, the precipitation phase morphology is in that order:ball→ball and needle→needle. During1hour at520℃, the morphology of precipitated phase is fine needle, along with the austenitic grain, there are little ball precipitated phase. After being aging for1hour at580℃, the needle-like precipitated phase coarsening too much, and the transformation from austenite to perlitic and bainite on the matrix. With prolonging of aging time, the needle-like precipitated phase increased, and in the internal cross grain growth. Aging precipitation phase for (Mn,Fe)7C3have two forms, the structure of ball precipitated phase is face-centered structure, needle precipitated phase is body structure, compared with ball precipitated phase, needle-like precipitated phase is more stable.(3)After1hour aging at520℃, the morphology of precipitated phase is fine needle, the micro strain minimum, compared with no aging treatment, hardness increased from215HBS to258HBS, impact value decreased from131J/cm to85.96J/c2. Abrasion loss reduced from1.7077g to1.0701. The result shows that the best aging process should make wear-resisting precipitated phase precipitated and did not cause the increase of micro strain. The best aging process parameter of this experimental steel is aging at520℃for1h.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Steel > Microstructure and properties of steel
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