The critical points and time-temperature-transformation(TTT)curves of the isothermal transformation diagrams for a high-speed steel casting on a horizontal centrifugal casting machine had been determined experimentall...The critical points and time-temperature-transformation(TTT)curves of the isothermal transformation diagrams for a high-speed steel casting on a horizontal centrifugal casting machine had been determined experimentally in the study.The effects of quenching temperature on the microstructures and properties of centrifugal casting high speed steel(HSS)roll has been investigated using scanning electron microscopy(SEM), light optical microscopy(LOM)and X-ray diffraction(XRD)as well as using tensile,impact,and hardness tests. The results show that the HSS roll has excellent hardenability and its matrix structure can be transformed into the martensite after being quenched in the sodium silicate solution.The retained austenite in the quenching structure increases and the hardness decreases when the quenching temperature exceeds 1,040℃.The tensile strength and impact toughness of HSS roll increase once the quenching temperature is raised from 980℃to 1,040℃. However,the tensile strength and impact toughness have no significant change when the quenching temperature exceeds 1,040℃.The HSS roll quenched at 1,040℃exhibits excellent comprehensive mechanical properties.展开更多
The as-cast microstructures of high carbon high speed steels(HC-HSS) made by sand casting,centrifugal casting and electromagnetic centrifugal casting,respectively,were studied by using of optical microscopy(OM) and D/...The as-cast microstructures of high carbon high speed steels(HC-HSS) made by sand casting,centrifugal casting and electromagnetic centrifugal casting,respectively,were studied by using of optical microscopy(OM) and D/max2200pc X-ray diffraction.The results show that the microstructure of as-cast HC-HSS is dominated by alloy carbides(W2C,VC,Cr7C3),martensite and austenite.The centrifugal casting and electromagnetic centrifugal casting apparently improve the solidification structure of HC-HSS.With the increase of magnetic intensity(B),the volume fraction of austenite in the HC-HSS solidification structure increases significantly while the eutectic ledeburite decreases.Moreover,the secondary carbides precipitated from the austenite are finer with more homogeneous distribution in the electromagnetic centrifugal castings.It has also been found that the lath of eutectic carbide in ledeburite becomes finer and carbide phase spacing in eutectic ledeburite increases along with the higher magnetic field strength.展开更多
基金supported by the innovation fund of small and medium-sized enterprise of Science&Technology Ministry of China under grant(07C26215110842).
文摘The critical points and time-temperature-transformation(TTT)curves of the isothermal transformation diagrams for a high-speed steel casting on a horizontal centrifugal casting machine had been determined experimentally in the study.The effects of quenching temperature on the microstructures and properties of centrifugal casting high speed steel(HSS)roll has been investigated using scanning electron microscopy(SEM), light optical microscopy(LOM)and X-ray diffraction(XRD)as well as using tensile,impact,and hardness tests. The results show that the HSS roll has excellent hardenability and its matrix structure can be transformed into the martensite after being quenched in the sodium silicate solution.The retained austenite in the quenching structure increases and the hardness decreases when the quenching temperature exceeds 1,040℃.The tensile strength and impact toughness of HSS roll increase once the quenching temperature is raised from 980℃to 1,040℃. However,the tensile strength and impact toughness have no significant change when the quenching temperature exceeds 1,040℃.The HSS roll quenched at 1,040℃exhibits excellent comprehensive mechanical properties.
基金supported by the special fund for basic scientifi c research of central colleges,Chang’an University (CHD2010JC015)the innovation fund of small and medium-sized enterprise of Science & Technology Ministry of China under grant no. 10C26213201139Beijing Education Committee patent outcome conversion item
文摘The as-cast microstructures of high carbon high speed steels(HC-HSS) made by sand casting,centrifugal casting and electromagnetic centrifugal casting,respectively,were studied by using of optical microscopy(OM) and D/max2200pc X-ray diffraction.The results show that the microstructure of as-cast HC-HSS is dominated by alloy carbides(W2C,VC,Cr7C3),martensite and austenite.The centrifugal casting and electromagnetic centrifugal casting apparently improve the solidification structure of HC-HSS.With the increase of magnetic intensity(B),the volume fraction of austenite in the HC-HSS solidification structure increases significantly while the eutectic ledeburite decreases.Moreover,the secondary carbides precipitated from the austenite are finer with more homogeneous distribution in the electromagnetic centrifugal castings.It has also been found that the lath of eutectic carbide in ledeburite becomes finer and carbide phase spacing in eutectic ledeburite increases along with the higher magnetic field strength.
