Improvement of SUP-9 Steel Fatigue Life by Laser Surface Processing

• Main Authors: LAN YANG-JUI, 藍陽瑞
• Other Authors: 蔡 顯 榮
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/93112413967925740718

碩士 === 國立臺灣科技大學 === 機械工程系 === 93 === The purpose of this study is to improve the fatigue life of SUP-9 steel by laser surface hardening treatment, and furthermore to investigate the hardening depth, the transformation, the microstructure fatigue fracture mode, and so on. Laser surface hardening conditions of the specimens shall be modulated by ROFIN-SINAR RS850 CO2 Laser machine that laser power is 5000W. In order to perform uniformly the dimension and surface painting quality of specimens, the manufacture and surface coating of specimens was done by CNC machine and spray painting method respectively. Firstly, in the experimental investigations the Laser surface hardening conditions, like as laser power, defocused distance, treatment time, shall be tested and optimized to avoid causing the surface melting situation. In fatigue test, the specimen shall be applied 70 kg of loading by SIMNZA fatigue machine. Finally, the hardening surface of specimen was observed by optic microscope. Furthermore, the hardening depth and the hardening distribution of specimen was measured by micro Vickers sclerometer. The orthogonal array of Taguchi method is used to arrange the laser experimental work. The two to five of four level control factors could be analyzed by this method of L16 (45). According to the experimental results, the fatigue life of SUP-9 steel that treated in the parameter conditions: the laser power is 940W；surface coating is B3; defocused distance is 60mm; rotation speed of specimen is 83 rpm; treatment time is 6 sec, will be promote one hundred times than the fatigue life of SUP-9 raw material.