Statistical analysis and optimization of process parameters in Ti6Al4V laser cladding using Nd:YAG laser

Abstract

The process parameters of laser cladding have great effect on the clad geometry and dilution. This investigation focuses on the influence of laser power (400–600W), scanning speed (500–700mm/min) and powder feed rate (30–60rev/min) on the shape factor and the cladding-bead geometry (layer width, layer height and molten depth) with regard to injecting Ti6Al4V (TC4) powder on TC4 substrate. The experimental design technique, central composite design (CCD) and response surface methodology (RSM) are used to build the mathematical model. By means of the developed model tested by the analysis of variance (ANOVA) method, the relationship between process parameters and output responses and the interaction among the process parameter are analyzed and discussed in detail. The analysis results indicate that powder feed rate is the dominant factor on the width and height of cladding coating while laser scanning speed has the strongest effect on molten depth of substrate. Finally, the validation results show that the calculated values are in good agreement with measured responses within the allowable range of cladding parameters being used. This makes it possible to acquire a good parameter combination for dilution control. Based on the results of optimization, it is observed that the low level of laser power and high level of laser scanning speed can produce cladding coatings with good quality when powder feed rate is around the center value.