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文中基于笔者课题组自行搭建的LMD系统,包括KUKA公司的KR60-3F型六轴机器人、IPG公司的YLS-2000-CT型激光器(P额:2 000 W、λ:1070 nm)、GTV公司的PF2/2型送粉器、自主研发的送气保护式环形光沉积头[18] (原理如图1所示)与基础工艺[19-20]。
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实验选用尺寸为50 mm×66 mm×6 mm的ZL101铸造铝合金为成形基板,表面经喷砂处理与丙酮洗净。粉末材料选用旋转电极工艺生产的AlSi10Mg铝合金,粒径为75~135 μm,显微形貌如图2所示。粉末的D10、D50和D90分别为90.23、107.10、134.6 μm,化学成分如表1所示。实验过程中采用纯氩气作为保护和粉末输送气体(图1)。
Element Al Si Mg Fe Ti Ni Mn Cu P Composition
(mass fraction)Bal. 9.99% 0.44% 0.43% 0.05% 0.009% 0.0086% 0.011% 0.0085% Table 1. Chemical composition of AlSi10Mg alloy powder
Effects of temperature field on properties of micro-structure of AlSi10Mg with laser metal deposition
doi: 10.3788/IRLA20210366
- Received Date: 2021-06-02
- Rev Recd Date: 2021-09-01
- Publish Date: 2022-06-08
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Key words:
- laser metal deposition /
- aluminum alloy /
- temperature field /
- porosity rate /
- properties of micro-structure
Abstract: Due to low laser absorption rate and high thermal conductivity, the properties of micro-structure of aluminum alloy formed by laser melting deposition (LMD) are greatly affected by temperature field. In order to analyze the temperature field of annular beam LMD aluminum alloy molten pool and its’ influence, optimize the forming quality and the performance of forming parts, the Ar-supplied protective LMD technology was used, the AlSi10Mg aluminum alloy forming experiment was carried out. The shape and change of the temperature field of molten pool were systematically analyzed, as well as the influence mechanism of the temperature field on the forming quality, porosity, the properties of micro-structure. The results show that the overall shape of the temperature field of the ring beam LMD aluminum alloy molten pool is "half crescent" with the opening in the scanning direction. With the increase of laser power, the temperature field shape becomes more and more sharp, and its high temperature rate, temperature gradient and average temperature also increase accordingly. The increase of the average temperature of the temperature field can increase the laser absorption rate, coarsen the micro-structure and reduce the micro-hardness. The temperature field affects the porosity rate of the formed part significantly and thus changing the tensile properties. Finally, when the average temperature is 857.7 ℃, the porosity rate is reduced to 2.1%, and the tensile strength is 305.6 MPa, and the elongation rate is 5.7%, which is 52.5% higher than the casting. It provides theoretical guidance for LMD aluminum alloy temperature field and properties of micro-structure control.