THE Torch Festival is the most significant and grandest celebration for all Yi communities across China’s Yunnan,Guizhou,and Sichuan provinces,with a history spanning over a thousand years.It reflects the Yi people’...THE Torch Festival is the most significant and grandest celebration for all Yi communities across China’s Yunnan,Guizhou,and Sichuan provinces,with a history spanning over a thousand years.It reflects the Yi people’s long-standing reverence for fire.Originating from the Yi ancestors’worship of fire,the festival was intended to drive away pests and evil spirits,protect crops,and represent prayers for a bountiful harvest.展开更多
A novel plasma torch nitriding technology was applied for the first time to improve the surface properties of M2 high-speed steel by adjusting different experimental parameters.The nitrogen content,precipitate,microst...A novel plasma torch nitriding technology was applied for the first time to improve the surface properties of M2 high-speed steel by adjusting different experimental parameters.The nitrogen content,precipitate,microstructure,mechanical property,and corrosion resistance of the nitrided layer were comprehensively analyzed using an ONH analyzer,scanning electron microscope(SEM),micro-area X-ray diffractometer,transmission electron microscope(TEM),Vickers microhardness tester,high-temperature wear tester,3D profilometer,tensile testing machine,and electrochemical workstation.The research results show that the novel plasma torch nitriding technology can achieve synergistic strengthening of nitrogen,carbon,and alloying element solid solution,precipitation strengthening,and martensitic structure on the surface of M2 high-speed steel.The nitrogen content on the specimen surface increased up to 0.17%,while the size and area of carbides were reduced by 89%and 86%,respectively,indicating a transformation towards fine nitrogen-rich precipitates.Compared to the original M2 steel,the nitrided specimens exhibited significant improvements in overall performance.The hardness increased from 228 HV_(0.2)to a maximum of 795 HV_(0.2),the wear coefficient decreased from a maximum of 0.8 to 0.49,the tensile strength increased from 753 MPa to a maximum of 934 MPa,and the corrosion current density decreased from 1.2×10^(−5)to a minimum of 1.9×10^(−6)A/cm^(2).展开更多
文摘THE Torch Festival is the most significant and grandest celebration for all Yi communities across China’s Yunnan,Guizhou,and Sichuan provinces,with a history spanning over a thousand years.It reflects the Yi people’s long-standing reverence for fire.Originating from the Yi ancestors’worship of fire,the festival was intended to drive away pests and evil spirits,protect crops,and represent prayers for a bountiful harvest.
基金supported by the National Science and Technology Major Project of China(No.HT-J2019-V-0023-0140)Open Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(No.SKLASS 2023-03)the Science and Technology Commission of Shanghai Municipality(No.20511107700).
文摘A novel plasma torch nitriding technology was applied for the first time to improve the surface properties of M2 high-speed steel by adjusting different experimental parameters.The nitrogen content,precipitate,microstructure,mechanical property,and corrosion resistance of the nitrided layer were comprehensively analyzed using an ONH analyzer,scanning electron microscope(SEM),micro-area X-ray diffractometer,transmission electron microscope(TEM),Vickers microhardness tester,high-temperature wear tester,3D profilometer,tensile testing machine,and electrochemical workstation.The research results show that the novel plasma torch nitriding technology can achieve synergistic strengthening of nitrogen,carbon,and alloying element solid solution,precipitation strengthening,and martensitic structure on the surface of M2 high-speed steel.The nitrogen content on the specimen surface increased up to 0.17%,while the size and area of carbides were reduced by 89%and 86%,respectively,indicating a transformation towards fine nitrogen-rich precipitates.Compared to the original M2 steel,the nitrided specimens exhibited significant improvements in overall performance.The hardness increased from 228 HV_(0.2)to a maximum of 795 HV_(0.2),the wear coefficient decreased from a maximum of 0.8 to 0.49,the tensile strength increased from 753 MPa to a maximum of 934 MPa,and the corrosion current density decreased from 1.2×10^(−5)to a minimum of 1.9×10^(−6)A/cm^(2).
