LUO Fang
,
YAO Jianhua
,
HU Xiaxia
,
CHAI Guozhong
钢铁研究学报(英文版)
Abstract: In this paper, H13 powder is cladded on P20 base during continuous CO2 laser, the influence of processing technologies such as the laser power is analyzed. The 3-D model of synchronous powder feeding is established under Gauss heat source, the simulation results are compared with the experimental data. The results show that the temperature field and the size of heat affected zone are affected by laser power. In the heat affected zone, experimental sizes are compared with simulative sizes, the average errors in width and in depth are 15% and 4.5%, respectively.
关键词:
ZHANG Qunli
,
YAO Jianhua
,
Jyoti Mazumder
钢铁研究学报(英文版)
Multilayer of laser direct metal deposition (DMD) was prepared by depositing a gas atomized prealloyed powder with a composition close to Inconel 718 alloy on Inconel 718 high temperature alloy substrate. The effects of the DMD parameters on the buildup rate and the structure of the deposited layer were studied. The laser DMD sample was further processed by a solution treatment. The microstructure and property of the laser DMD zone before and after heat treatment were investigated as well. The results show that the laser parameters of actual laser power of 650 W, scanning speed of 58 mm/s, beam diameter of 1 mm, powder feed rate of 645 g/min, with a corresponding specific energy of 90-130 J/mm2, can be recommended as optimum parameters for high buildup rate of Inconel 718 alloy. Under the condition of optimized parameters, a directional solidification microstructure was obtained and the average distance between the columnar crystals was 5-10 μm. The microcomposition segregation was found between the columnar crystal trunk and columnar crystal. The elements of Nb, Mo, Ti concentrated in the columnar crystal trunk. After the heat treatment, the segregation was greatly minimized, and the segregation ratios were close to 1. The hardness of the laser deposited layer did not show obvious difference along the height of the layer either for the asdeposited layer or for the heat treated layer. However, the microhardness of the laser DMD zone after heat treatment was obviously higher than that after the asdeposited treatment. During the heat treatment process, some Nb and Morich phases precipitated and strengthened DMD layer.
关键词:
laser DMD; Inconel 718 alloy; composition segregation; microstructure; hardness
