| DONG Gang,YOU Hanxiao,MAO Kaijun,YUAN Nengjun,GE Minjie,YU Xuezhen,ZHANG Qunli,YAO Jianhua.Effect of Si Element Content on the Manufacturing Process and Corrosion Performance of Laser Clad 316L[J],53(3):179-190 |
| Effect of Si Element Content on the Manufacturing Process and Corrosion Performance of Laser Clad 316L |
| Received:January 07, 2023 Revised:May 06, 2023 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.03.018 |
| KeyWord:laser cladding 316 Si process properties corrosion performance |
| Author | Institution |
| DONG Gang |
Institute of Laser Advanced Manufacturing, College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Hangzhou , China |
| YOU Hanxiao |
Institute of Laser Advanced Manufacturing, College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Hangzhou , China |
| MAO Kaijun |
Zhejiang Dongbin Rubber Plastic Co., Ltd., Zhejiang Zhoushan , China |
| YUAN Nengjun |
Zhejiang Dongbin Rubber Plastic Co., Ltd., Zhejiang Zhoushan , China |
| GE Minjie |
Institute of Laser Advanced Manufacturing, College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Hangzhou , China |
| YU Xuezhen |
Institute of Laser Advanced Manufacturing, College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Hangzhou , China |
| ZHANG Qunli |
Institute of Laser Advanced Manufacturing, College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Hangzhou , China |
| YAO Jianhua |
Institute of Laser Advanced Manufacturing, College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou , China;Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Hangzhou , China |
|
| Hits: |
| Download times: |
| Abstract: |
| As research into metal additive manufacturing continues, laser cladding is gaining increasing attention in the forming and reworking of complex parts. The heating rate and cooling rate in laser processing are extremely high, which can lead to cracks and damage to the cladding layer. The risk of cracking is reduced by increasing the Si content of the laser cladding powder. This lowers the melting point of the powder, thereby reducing the heat input during processing. However, the effect of Si is not limited to lowering the melting point of the powder. In order to investigate the effect of Si on the fabrication process and the corrosion performance of cladding layers, 316L cladding layers with different Si contents were fabricated on 316L substrates with 0.8% Si-316L, 1.2% Si-316L and 1.6% Si-316L powders, respectively. The macroscopic morphology and microstructural composition of the cladding samples were characterized by laser confocal microscopy, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. It was found that the thickness of the laser cladding layer increased as the Si content increased. The average thickness of a single layer increased from 700 μm at 0.8% Si to 800 μm at 1.2% Si and to 900 μm at 1.6% Si, increasing by 14% and 29%. At the same time, because the laser cladding layers were stacked layer by layer, the entire layer underwent a complex thermal cycling process that greatly affected the stability of the final cladding properties. By increasing the Si content of the powder, the number of stacked layers could be reduced. This would result in a more consistent quality of the final layer. In the meantime, the oxidation of elemental Si produced SiO2, which protected the melt pool well and reduced the oxidation of the cladding layer. The results of the TG tests showed that 0.8% Si oxidized at high temperatures and gained an average of 32% by weight, whereas 1.6% Si oxidized at a rate of only 19% by weight. Si preferentially reacted with oxygen to protect the remaining elements in the melt pool for thermodynamic reasons. This protection was enhanced by the extremely high melt pool cooling rate, ultimately leading to improved oxidation of metallic elements in the cladding at high temperature. In addition, the corrosion resistance of the molten cladding could be improved by the oxidation of elemental Si to SiO2. The number of pits on the sample surface decreased significantly with increasing Si content in the electrochemical tests. The electrochemical results showed that the corrosion current decreased from 2.039×10–6 A.cm–2 to 1.889×10–6 A.cm–2 and 1.422×10–6 A.cm–2 with increasing elemental Si content, while the self-corrosion potential moved in a positive direction. From the dynamic polarization curves, it could be seen that as the Si content increased, the corrosion performance increased mainly in the form of a longer passivation interval. This was most likely due to the conversion of Si to SiO2 which was enriched on the Cr2O3 passivation layer. This compensated for the lack of Cr2O3 passivation. The pitting potentials of all three increased from 0.8% Si (0.4 V) to 1.2% Si (0.6 V) and 1.6%Si (0.9 V). The impedance spectral data also showed that the impedance of the specimens increased with Si content. In particular, the passivation impedance R2 increased from 0.65×105 Ω.cm2 to 3.55× 105 Ω.cm2 and 4.08×105 Ω.cm2, indicating that the oxidation of elemental Si to form SiO2 improved the passivation layer of the 316L surface layer, effectively improving the corrosion resistance of the cladding layer. |
| Close |
|
|
|