The multi-pass hot compression test of 7055 aluminum alloy was performed at different temperatures and then the samples were heat treated by T6 heat treatment.The compressed samples were analyzed by OM and TEM.The res...The multi-pass hot compression test of 7055 aluminum alloy was performed at different temperatures and then the samples were heat treated by T6 heat treatment.The compressed samples were analyzed by OM and TEM.The results reveal that the average aspect ratio of the grains in the specimens compressed first decreases and then increases,the dislocation density decreases and subgrain diameter increases with the increase of deformation temperature.The effects of deformation temperature on the microstructure and mechanical properties of 7055 aluminum alloy after heat treatment were investigated by means of OM and mechanical property test.The results indicate that the deformation temperature significantly influences microstructure and mechanical property of 7055 aluminum alloy.The volume fraction of recrystallization grains presents a ＂fall-rise＂ pattern with the deformation temperature rising.The mechanical properties get better when the volume fraction of recrystallization grains decreases.Moreover,the volume fraction of recrystallization grain has a minimum value,appropriately 45%,and the sample exhibits the highest strength and elongation at the deformation temperature of 400 ℃.展开更多
Brittle pro-eutectoid cementite that forms along prior-austenite in hypereutectoid steels is deleterious to mechanical properties. The optimum process parameters which suppress the formation of pro-eutectoid cementite...Brittle pro-eutectoid cementite that forms along prior-austenite in hypereutectoid steels is deleterious to mechanical properties. The optimum process parameters which suppress the formation of pro-eutectoid cementite in hypereutectoid steels with carbon content in the range of 0.8%-1.3% in mass fraction, were investigated. Pro-eutectoid cementite formation is effectively hindered by increasing the deformation temperature and decreasing the amount of strain. Transformation at lower temperatures close to the nose of the cooling-transformation diagram also reduces the tendency of the formation of pro-eutectoid cementite. Control of prior-austenite grain size and grain boundary conditions is important. Due to larger number of nucleation sites, finer prior-austenite grain size results in the acceleration of transformation to pro-eutectoid cementite. However, large prior-austenite and straight boundaries lead to less nucleation sites of pro-eutectoid cementite. The cooling rate and carbon content should be reduced as much as possible. The transformation temperature below 660 °C and the strain of 0.5 at deformation temperature of 850 °C are suggested.展开更多
基金Project(CHALCO-2007-KJ-02) supported by the Technology Development Program of Aluminum Corporation of ChinaProject (2011BS0802) supported by the Natural Science Foundation of Inner Mongolia,ChinaProject(NJZY11075) supported by the Research Fund for the Higher Education of Inner Mongolia,China
文摘The multi-pass hot compression test of 7055 aluminum alloy was performed at different temperatures and then the samples were heat treated by T6 heat treatment.The compressed samples were analyzed by OM and TEM.The results reveal that the average aspect ratio of the grains in the specimens compressed first decreases and then increases,the dislocation density decreases and subgrain diameter increases with the increase of deformation temperature.The effects of deformation temperature on the microstructure and mechanical properties of 7055 aluminum alloy after heat treatment were investigated by means of OM and mechanical property test.The results indicate that the deformation temperature significantly influences microstructure and mechanical property of 7055 aluminum alloy.The volume fraction of recrystallization grains presents a ＂fall-rise＂ pattern with the deformation temperature rising.The mechanical properties get better when the volume fraction of recrystallization grains decreases.Moreover,the volume fraction of recrystallization grain has a minimum value,appropriately 45%,and the sample exhibits the highest strength and elongation at the deformation temperature of 400 ℃.
基金Project(51222405)supported by the National Science Foundation for Outstanding Young Scholars of ChinaProject(51034002)supported by the National Natural Science Foundation of China+1 种基金Project(132002)supported by the Fok Ying Tong Education Foundation,ChinaProject(N120502001)supported by the Basic Scientific Research Operation of Center University of China
文摘Brittle pro-eutectoid cementite that forms along prior-austenite in hypereutectoid steels is deleterious to mechanical properties. The optimum process parameters which suppress the formation of pro-eutectoid cementite in hypereutectoid steels with carbon content in the range of 0.8%-1.3% in mass fraction, were investigated. Pro-eutectoid cementite formation is effectively hindered by increasing the deformation temperature and decreasing the amount of strain. Transformation at lower temperatures close to the nose of the cooling-transformation diagram also reduces the tendency of the formation of pro-eutectoid cementite. Control of prior-austenite grain size and grain boundary conditions is important. Due to larger number of nucleation sites, finer prior-austenite grain size results in the acceleration of transformation to pro-eutectoid cementite. However, large prior-austenite and straight boundaries lead to less nucleation sites of pro-eutectoid cementite. The cooling rate and carbon content should be reduced as much as possible. The transformation temperature below 660 °C and the strain of 0.5 at deformation temperature of 850 °C are suggested.
