| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 104 === In this study, a 50 W CO2 laser was carried out for cladding experiment.
Temperature sensing device and image monitoring system were adopted to monitor the layer deposition on stainless steel substrate. Processing was modified by different laser power, velocity, and focus position to reach an optimum morphology and mechanical properties of the cladding on demand.
The analyses for thermal conductivity of 304L stainless steel powder, transporting gas flow rate on the powder structure, and the interaction between powder and laser were made to find proper processing parameters, which were tested to demonstrate the feasibility.
ANSYS was used to calculate distribution of temperature for laser irradiates on moving substrate in the numerical part. Experimentally with single and multi-layer cladding, it is to compare the differences in 3D printing. Due to the clad profile cooling by substrate and workpiece itself, the equipment was applied to monitor temperature signal for multi-pass analysis and to predict the relationship between the melt pool temperature and cladding profile. The results show that a preheating substrate by laser can enhance flatness of the cladding profile. Besides, grain refinement phenomenon might occur at large power and low cladding speed, the hardness of workpiece would also increase.
Key words: Multilayer cladding；Temperature signal；Profile control
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