高温下小区域变形长时测量方法的研究及其应用

RESEARCH ON THE METHOD OF MEASURING LONG-TERM DEFORMATION IN A SMALL REGION AT HIGH TEMPERATURE AND ITS APPLICATION

对于高温下服役的构件 ,焊缝区域较为狭小 ,焊缝以及热影响区 (HAZ)的高温变形难以用传统的方法测量。文中利用石英光纤和数字图象处理技术 ,研究开发一种能在高温下长时测量局部变形的新方法和测量系统 ,分析讨论了测量精度 ,并用于HK40炉管焊缝长时蠕变变形的测量 。

For conventional uniaxial tensile creep testing, the measured creep deformation is only an average within a gauge length High temperature deformation of weldment and heat affected zone (HAZ) can hardly be measured by conventional displacement gauge due to narrow weld region for the components serviced at high temperature In this paper, a method for measuring long term local deformation at high temperature is developed by quartz optical fiber and technique of digital image analysis High temperature characteristics of quartz optical fibers are studied The feasibility of using the optical fibers as measuring marks is discussed Extraction of the light spots and determination of their centers are solved by use of the point dependence technique, especially the extraction technique of sub pixels, and the region center method Noises of the image are removed to enhance image quality A measuring system is set up, which utilizes the merits of quartz optical fiber, long distance microscope and computer image analysis performed by the designed software The measuring accuracy of the system is discussed for the long term creep deformation The developed method is applied to measure creep deformation of actual weld metal of HK40 furnace tube On the basis of this, the creep property of actual HK40 weld metal is analyzed and compared with that of base metal in HK40 furnace tubes