研究目的
Investigating the effects of processing parameters including scanning speed, laser power and powder feeding rate on grain size of the solidified track during laser metal deposition.
研究成果
The study reveals the relationship between processing parameters and grain size of laser metal deposition and the underlying mechanisms. It is reasonable to expect that this study will contribute to the microstructure and properties control of additive manufacturing.
研究不足
The study focuses on the relationship between processing parameters and grain size in laser additive manufacturing of superalloy, but the transition of the solidified structure from planar front to columnar dendrites to equiaxed dendrites is not quantified.
1：Experimental Design and Method Selection:
A three-dimensional model considering heat transfer, phase change and Marangoni convection flow was developed to simulate the solidification parameters especially cooling rate (G × R).
2：Sample Selection and Data Sources:
The substrate and powder material were 1Cr13 stainless steel and Ni45 alloy powder, respectively.
3：List of Experimental Equipment and Materials:
An Nd: YAG laser with a maximum power of 1000 W, a
4：06 μm wavelength and a 160 mm focal length was used as the heat source. The powder was fed coaxially and protected by highly purified argon shielding gas. Experimental Procedures and Operational Workflow:
Metallographic samples were cut, mounted, milled, polished, and etched in aqua regia solution sequentially. The solidified structure was observed by POLYVAR optical microscopy (OM) and ZEISS EVO18 scanning electron microscope (SEM). The grain size was measured via Nano Measurer software.
5：Data Analysis Methods:
The relationship between grain size and cooling rate was analyzed.
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