The developmental situation of space welding technology at home and abroad is introduced. Then it is put forward that the designing scheme and the computer aided design （CAD） method of main single lens of the domest...The developmental situation of space welding technology at home and abroad is introduced. Then it is put forward that the designing scheme and the computer aided design （CAD） method of main single lens of the domestic space electron beam gun with equal-diameter three-cylinder simple lens, and the flowing-pipe way of calculating the space charge density of the main lens area ,in the electron gun is analyzed. The parameters calculation of the focusing system is completed through Language C utilizing computer programming and a satisfying result is gotten. The result shows that the calculation and design method are correct ： the dispersed focusing current of electron beam is less, the beam section is less in the deflected magnetic field, the minimal radius of beam spot on the workpiece is about 0.65615mm, and all these can meet the requirements of the space welding and cutting.展开更多
The solution of static deformation of two homogeneous, isotropic, and perfectly elastic half-spaces in welded contact due to a long dip-slip fault with uniform slip is well known. The aim of the present article is to ...The solution of static deformation of two homogeneous, isotropic, and perfectly elastic half-spaces in welded contact due to a long dip-slip fault with uniform slip is well known. The aim of the present article is to obtain the static deformation of two homogeneous, isotropic, and perfectly elastic half-spaces in welded contact due to nonuniform slip along a long dip-slip fault. The fault is vertical and lies entirely in the lower half-space, extending up to the interface. Four slip profiles are considered： lin- ear, parabolic, elliptic, and cubic. Closed-form expressions for the elastic residual field have been ob- tained for the different slip profiles. The displacement field due to four nonuniform slip profiles is com- pared with the displacement field due to uniform slip. For comparison, we have assumed the source potency for different slip profiles to be the same, which is achieved by taking the fault slip at the inter- face constant and varying the fault width. It is found that the displacement field varies significantly at the fault width rather than at the interface. Moreover, uniform slip along the fault makes the edges singular. This singularity at the lower edge is not present in the case of nonuniform slip along a long dip-slip fault.展开更多
In order to realize automatic weld seam tracking for pipeline ultrasonic flaw inspection, an image processing algorithm based on HSI color space was presented. Since the color tones of weld seam were different from th...In order to realize automatic weld seam tracking for pipeline ultrasonic flaw inspection, an image processing algorithm based on HSI color space was presented. Since the color tones of weld seam were different from the parent metal, weld seam images were transformed to HSI color space. In the HSl colar space, the weld seam and base metal area can be apparently distinguished. By using this image processing algorithm, the edges and centerline of pipeline weld seam can be correctly extracted. An industrial application system was developed based on the image processing algorithm, and the image processing time is less than 70 ms and the accuracy of weld seam recognition is better than 2mm.展开更多
The microstructure evolution of the weld metal （WM） region in a Ni-based 718 superaUoy is discussed. The superalloy sheets were welded using the tungsten inert gas process at different heat inputs. The precipitates ...The microstructure evolution of the weld metal （WM） region in a Ni-based 718 superaUoy is discussed. The superalloy sheets were welded using the tungsten inert gas process at different heat inputs. The precipitates and dendrites in the WM of each joint were analyzed by optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy （ EDS）. Statistics on the dendrite arm spacing and precipitates were obtained from the metallographs. Using the alloy composition determined by EDS and the phase diagram obtained using ThermoCalc, the equilibrium distribution coefficient of Nb, the temperature range of solid/liquid coexistence, and the distribution and morphology of Laves phase in different subregion of the WM were analyzed. There is lamellar segregation, regional segregation, and microsegregation in the WM. As the heat input increases, the arm spacing and the microsegregation increase. At a fixed heat input, the microsegregation rate is smallest in the crater, but with the macrosegregation seriously.展开更多
【目的】旨在分析显微组织对钢轨闪光焊焊接接头纵断面硬度的影响规律。【方法】采用光学电子显微镜(Optical electron microscope,OEM)、扫描电镜(Scanning electron microscope,SEM)及电子背散射衍射(Electron backscatter diffractio...【目的】旨在分析显微组织对钢轨闪光焊焊接接头纵断面硬度的影响规律。【方法】采用光学电子显微镜(Optical electron microscope,OEM)、扫描电镜(Scanning electron microscope,SEM)及电子背散射衍射(Electron backscatter diffraction,EBSD)等技术手段,对某厂生产的欧标R260级珠光体钢轨闪光焊焊接接头不同微区硬度、显微组织、珠光体片层间距、晶粒取向及尺寸等特征参数进行表征与研究,阐明接头不同微区显微组织及晶粒特征参数对接头纵断面硬度影响规律。【结果】结果表明,在一定的工艺条件下,采用平均值和反映测量误差正态分布特点的标准误差值来表示特定材质珠光体钢轨中珠光体片层间距更准确;晶粒尺寸的大小较珠光体片层间距对珠光体钢轨接头纵断面硬度的影响更为明显。【结论】为钢轨成分设计及其焊接工艺的优化提供了理论依据。展开更多
文摘The developmental situation of space welding technology at home and abroad is introduced. Then it is put forward that the designing scheme and the computer aided design （CAD） method of main single lens of the domestic space electron beam gun with equal-diameter three-cylinder simple lens, and the flowing-pipe way of calculating the space charge density of the main lens area ,in the electron gun is analyzed. The parameters calculation of the focusing system is completed through Language C utilizing computer programming and a satisfying result is gotten. The result shows that the calculation and design method are correct ： the dispersed focusing current of electron beam is less, the beam section is less in the deflected magnetic field, the minimal radius of beam spot on the workpiece is about 0.65615mm, and all these can meet the requirements of the space welding and cutting.
基金supported by the Major Research Project and Junior Research Fellowship from the University Grant Commission,New Delhi
文摘The solution of static deformation of two homogeneous, isotropic, and perfectly elastic half-spaces in welded contact due to a long dip-slip fault with uniform slip is well known. The aim of the present article is to obtain the static deformation of two homogeneous, isotropic, and perfectly elastic half-spaces in welded contact due to nonuniform slip along a long dip-slip fault. The fault is vertical and lies entirely in the lower half-space, extending up to the interface. Four slip profiles are considered： lin- ear, parabolic, elliptic, and cubic. Closed-form expressions for the elastic residual field have been ob- tained for the different slip profiles. The displacement field due to four nonuniform slip profiles is com- pared with the displacement field due to uniform slip. For comparison, we have assumed the source potency for different slip profiles to be the same, which is achieved by taking the fault slip at the inter- face constant and varying the fault width. It is found that the displacement field varies significantly at the fault width rather than at the interface. Moreover, uniform slip along the fault makes the edges singular. This singularity at the lower edge is not present in the case of nonuniform slip along a long dip-slip fault.
文摘In order to realize automatic weld seam tracking for pipeline ultrasonic flaw inspection, an image processing algorithm based on HSI color space was presented. Since the color tones of weld seam were different from the parent metal, weld seam images were transformed to HSI color space. In the HSl colar space, the weld seam and base metal area can be apparently distinguished. By using this image processing algorithm, the edges and centerline of pipeline weld seam can be correctly extracted. An industrial application system was developed based on the image processing algorithm, and the image processing time is less than 70 ms and the accuracy of weld seam recognition is better than 2mm.
文摘The microstructure evolution of the weld metal （WM） region in a Ni-based 718 superaUoy is discussed. The superalloy sheets were welded using the tungsten inert gas process at different heat inputs. The precipitates and dendrites in the WM of each joint were analyzed by optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy （ EDS）. Statistics on the dendrite arm spacing and precipitates were obtained from the metallographs. Using the alloy composition determined by EDS and the phase diagram obtained using ThermoCalc, the equilibrium distribution coefficient of Nb, the temperature range of solid/liquid coexistence, and the distribution and morphology of Laves phase in different subregion of the WM were analyzed. There is lamellar segregation, regional segregation, and microsegregation in the WM. As the heat input increases, the arm spacing and the microsegregation increase. At a fixed heat input, the microsegregation rate is smallest in the crater, but with the macrosegregation seriously.
文摘【目的】旨在分析显微组织对钢轨闪光焊焊接接头纵断面硬度的影响规律。【方法】采用光学电子显微镜(Optical electron microscope,OEM)、扫描电镜(Scanning electron microscope,SEM)及电子背散射衍射(Electron backscatter diffraction,EBSD)等技术手段,对某厂生产的欧标R260级珠光体钢轨闪光焊焊接接头不同微区硬度、显微组织、珠光体片层间距、晶粒取向及尺寸等特征参数进行表征与研究,阐明接头不同微区显微组织及晶粒特征参数对接头纵断面硬度影响规律。【结果】结果表明,在一定的工艺条件下,采用平均值和反映测量误差正态分布特点的标准误差值来表示特定材质珠光体钢轨中珠光体片层间距更准确;晶粒尺寸的大小较珠光体片层间距对珠光体钢轨接头纵断面硬度的影响更为明显。【结论】为钢轨成分设计及其焊接工艺的优化提供了理论依据。
