通过几何尺寸检测、射线检测、化学成分分析、力学性能检测、宏观微观组织分析等方法,对某φ660 mm X70钢级输气管道环焊缝裂纹产生原因进行了分析。结果表明:裂纹产生于环焊缝6点钟附近,环焊缝焊趾部位存在的未熔合缺陷是裂纹产生的根...通过几何尺寸检测、射线检测、化学成分分析、力学性能检测、宏观微观组织分析等方法,对某φ660 mm X70钢级输气管道环焊缝裂纹产生原因进行了分析。结果表明:裂纹产生于环焊缝6点钟附近,环焊缝焊趾部位存在的未熔合缺陷是裂纹产生的根本原因。在附加应力的作用下,裂纹沿着根焊和填充焊金属中的孔洞和焊渣发生了进一步扩展开裂。展开更多
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
文摘通过几何尺寸检测、射线检测、化学成分分析、力学性能检测、宏观微观组织分析等方法,对某φ660 mm X70钢级输气管道环焊缝裂纹产生原因进行了分析。结果表明:裂纹产生于环焊缝6点钟附近,环焊缝焊趾部位存在的未熔合缺陷是裂纹产生的根本原因。在附加应力的作用下,裂纹沿着根焊和填充焊金属中的孔洞和焊渣发生了进一步扩展开裂。
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.
