研究目的
Investigating the influence of key parameters (laser beam power, scanning speed, and defocus) on the dilution and residual stress of CoCr1.5FeNiNb0.5 coating prepared by laser cladding, and optimizing these parameters to achieve minimum dilution and residual stress using multi-objective quantum-behaved particle swarm optimization algorithm.
研究成果
The study successfully modeled the influence of laser cladding parameters on dilution and residual stress using response surface methodology. The most significant parameter on dilution was defocus, while for residual stress, it was scanning speed. The MOQPSO algorithm was effective in optimizing both dilution and residual stress simultaneously, providing a Pareto solution. The CoCr1.5FeNiNb0.5 HEA coating, manufactured with optimized parameters, consisted of FCC and Laves phase and exhibited a hardness of nearly 600Hv.
研究不足
The study acknowledges that the 'Lack of Fit' for the residual stress model was significant due to the relatively unstable test data of residual stress. Each reported residual stress value was the average of 5 measurements, indicating potential variability in the data.
1：Experimental Design and Method Selection:
The study utilized response surface methodology (RSM) based on the Box-Behnken Design (BBD) to design the experiment, analyze, and optimize the experimental model. The experiment consisted of four factors and three levels of each factor.
2：Sample Selection and Data Sources:
CoCr
3：5FeNiNb5 high entropy alloy (HEA) coatings were prepared by laser cladding on 32CrNi2MoVA substrate. The powders were mixed with spherical powder (i.e., iron, chromium, cobalt, nickel, iron niobium) with purity>5wt% and power size of 100~150μm. List of Experimental Equipment and Materials:
A
4：5 kilowatts fiber laser with 1080nm wavelength and spot diameter of about 5mm was used for the laser cladding process. The samples were stationary, and the laser was controlled by a CNC motion control system. Experimental Procedures and Operational Workflow:
The thickness of the pre-placed layer was
5：2mm. Prior to the laser cladding process, the samples were dried for 2h at 120°C. The specimens used to observe the dilution were cut transverse to the deposition direction by electro-discharge machining. Data Analysis Methods:
The residual stresses of the HEA coatings were tested by X-ray diffraction (μ-X360, Pulstec Inc., Japan) equipped with a Cr-Kα. The X-ray beam diameter was 0.5mm, and the diffracted Cr-kα characteristic X-ray from a phase {220} plane was detected with a diffraction angle (2θ) of 120–135°.
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