Wire-Feeding Based Laser 3D Printing for Metal Additive Manufacturing and Material Characterization

• Main Author: 江驊晟
• Other Authors: 郭聰源
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/gtx69c

碩士 === 南臺科技大學 === 機械工程系 === 106 === 3D printing of metal objects has gained widespread attention as the finished products are arguably much stronger and durable than those made of thermoplastics. Wire feed metal deposition, which involves the use of a layered metal wire to create a predetermined 3D object, is an attractive developing technology for additive manufacturing of metal objects as compared to conventionally used laser sintering of metal powders. Using a metal wire has advantages over powder-based laser sintering like better mechanical properties, increased deposition rates, lower costs and improved material usage efficiency. In this study, we have developed a metal-based 3D printing process using an Nd:YAG laser single pass welding process with a 100μm stainless steel wire as the source material. We have studied the effects of process parameters like power, laser pulse duration, pulse frequency, wire feeding speed and stage speed on the welding bead morphology, width and height. Furthermore, five layers were coated using different welding parameters and the electron backscatter diffraction (EBSD), micro hardness and tensile test were performed for characterization. The EBSD observations show that when the average voltage, laser pulse duration and pulse frequency increase, the melt pool become larger and the proportion of ferrite increases significantly. On the other hand, when the wire feeding speed becomes faster and the stage speed becomes slower, the height of the welding bead increases and the proportion of ferrite decreases. The micro hardness results show that variations in the five parameters does not considerably effect hardness. The substrate micro hardness is in the range of 160-170 Hv0.1 and the micro hardness of the heat affected zone (HAZ) between the metal substrate and the first layer is significantly increased to a value between 230-240Hv0.1 while the micro hardness of the coating zone is 230~245 Hv0.1. The tensile test shows similar results when the average voltage, laser pulse duration and pulse frequency are varied. However, as the wire feeding speed becomes faster and stage speed becomes slower, the tensile strength increases significantly with maximum of 810 MPa and a minimum of 715 MPa. The additive process used in this study can be an attractive alternative for 3D printing of small metal objects.