Process Parameter Optimization on Selective Laser Melting of CuSn10 Powders Based on Response Surface Methodology

Abstract

Abstract A shaping test of CuSn10 powders was carried out by using the selective laser melting (SLM) technology to study influences of process parameters of SLM on compactness of specimens. Meanwhile, process parameters were optimized based on the response surface methodology. Meanwhile, phase composition and microstructure of formed part were analyzed by XRD and OM. Results demonstrated that as the energy density of laser body increases from 146.7 J·mm-3 to 181.3 J·mm-3, pores of samples decrease and the compactness increases from 98.97% to about 99.7%. Subsequently, the compactness begins to decrease with the continuous increase of laser energy density. The incomplete melting of powder under low energy density and gasification of powders under high energy density are major factors that influence the compactness. Over low or high laser energy density is disadvantageous for the improvement of compactness. A mathematical model of interaction between three factors (laser power, laser scanning speed and scanning space) and response value (compactness) was built up by using the BBD principle design test of response surface methodology. The degree of fitting (R2) and correction coefficient (R2 adj) of the model were 0.9952 and 0.9866, which agree well with the fitting degree of experimental tests. Among three factors, influences of laser power and scanning speed on compactness are equivalent and more significant than scanning space. The optimal process parameters which were predicted by the model were laser power=331.471 W, scanning speed=648.045 mm·s-1, scanning space=69.9302 μm. Under this circumstance, the compactness of CuSn10 powders after SLM is 99.75%. According to experimental verification, the practical value of compactness is 99.74%, showing a very small relative error. This proves that the BBD model is reliable. The shaped part is mainly composed of α-Cu phase and metastable phase β’-Cu13.7Sn. Compared with the original powders, the content of metastable phase β’ increases significantly, while the δ-Cu41Sn11 phase disappears.