SUS403麻田散鐵不銹鋼熱機處理後機械性質於沖蝕磨耗研究

• Main Authors: Chaolin Wu, 吳朝麟
• Other Authors: 溫東成
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/22264928103085278052

碩士 === 中華技術學院 === 機電光工程研究所碩士班 === 94 === High stressed turbine blades and valves are often made by Matensitic stainless steel. Fluid combined with particles striking the surface by different angles that makes erosion the main destructive mechanism. In order to look after the strength and the toughness, the material will be worked with quenching and tempering. However, the grains came out after Austenitization are bigger that worsen the mechanism. Therefore, controlling grains growing is what we are working at this research. This research processed by control rolling between Austenitization and air cooling quenching in order to grain refinement. Experienced group is to hold the material at 1010℃ for 2 hours. And then work with hot rolling with 15%, 30% and 50% definitions. Rolling temperature of input and output is about 850℃ and 700℃. After air cooling quenching, we work with tempering by using different from temperature 200℃ to 500℃. And then compare with non-rolling material. In order to understand the organization and the mechanisms of different isothermal transformative value after rolling, we place 30% definition material to 600℃ oven with 1 and 24 hour constant temperatures. And then take out and cooling semi-finished and finished transformative value material. The topics of the research are the mechanisms shown after applying with different processes, different erosion rates and erosion mechanisms after working by different erosion angles. It is also one of the research topics that the outcome of the hardness of different grain size to the erosion rates. What was found from the research: Inverse ratio was shown between grain size and definition after rolling. The average diameter size for non-rolling is 25.6μm; 15% definition is 9.3μm and 30% definition is 6.5μm. There is carbide found after 200℃ to 500℃ tempering. Significant secondary hardening was found at 500℃ tempering. It is with the highest hardness but bad at tractility. With 600℃ tempering, embritlement was found at Matensitic stainless steel and with the lowest hardness. Rolling amount, tensile strength and elongation are with direct ratio. The highest pulling resistances are happened when they are experiencing 500℃. The main reason is the secondary hardening. The lowest pulling resistance is happened when they are experiencing 600℃. It's the phenomenon of Martensite decomposing to Ferrite. As to the elongation rate, the highest rate comes up when it's with 600℃. The cracking rate slows down when the cracks reaches to Ferrite which is decomposed from Martensite. Moreover, it was also found the direct ratio between Rolling amount and impact energy. The lowest impact energy happens when it's with 500℃, and the highest impact energy is with 600℃. It's been discovered from the research of tensile test and impact test that the producing of reduced grain and result of preferred orientation contribute the ductility and toughness which are ones of the mechanisms. It is found the different fracture behaviors resulted by different erosive angles from the observation of the erosive breaking surface. The main characteristic of the erosive mechanism at the angle of 15° is cutting, therefore, the rate of erosion is lower. When it is with at the angle of 45°, it comes with not only cutting but also ploughing. Thanks for the higher horizontal and vertical components, we consider it is the best rate of erosion wear at the angle of 45°. The rate of erosion wears declines from 45° to 90°. It is with the lowest rate of erosion wear when the erosive mechanism is indentation crater. Therefore, the influence of erosive angle to the rate of erosion is bigger than the hot treatment to the rate of erosion. We also study from this experiment this material shows the representative curve. After the tempering heat treatment, it is found the rate and the depth of erosion is greater at 500℃ than at any other degrees of temperature. It is theoretically considered as the material brings secondary hardening at 500℃. The erosive crack grows along the grain boundary; erosive affection brings away the whole broken grain. These results the loss of the material.