The Effect of Laser Surface Treatment on Alloy 52

• Main Authors: Chang-ChunHuang, 黃証群
• Other Authors: Hwa-Teng Lee
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/ynhjb5

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 101 === Laser Surface Treatment (LST) is used to repair the surface of overlaid nickel based metal Alloy 52 in this study. In simulating of welding decay by aging heat treatment, chromium carbide had precipitated in grain boundary, caused the decrease of corrosion resistance. Laser Surface Melting (LSM) is now considered to be a solution of grain boundary segregation. In addition to the investigation of metallurgic, Modified Huey Test and DL-EPR were applied to evaluate the improvement of corrosion resistance. Surface Residual Stress was examined by High-Speed Hole-Drilling strain gauge method. In comparison with As-Welding (AW), the tensile residual stress had decreased after 650℃ aging heat treatment. LSM had increased the surface tensile residual stress that the highest tensile residual stress reached to 238.79MPa, but still lower than its own yielding stress. Metallurgic showed that chromium and titanium carbide were resolved and redistributed in melting zone, which made the intergranular and interdendritic corrosion markedly improved. However, the un-melted carbide in the heat effect zone lowered the corrosion resistance and pitting was discovered. The DL-EPR results revealed that the sensitization value (DOS, Ir/Ia) which was elevated after aging heat treatment had reduced by LSM, indicated the higher corrosion resistance. Laser surface treatment was proven to be an effective technique for the welding decay of Alloy 52 weldment surface.