Decomposition of cellular structure in selective laser melted Cu–Zn–Si silicon brass and its influence on microstructure, mechanical and corrosion properties

Abstract

Brass alloys containing low boiling-point element zinc are hard to be formed by selective laser melting (SLM). In this study, a Cu-12.9Zn-2.5Si silicon brass was produced successfully by SLM via optimizing process parameters, and then subjected to isothermal annealing at 873 K with different holding time. The evolutions of microstructure, mechanical and corrosion properties were investigated systematically by X-ray diffraction, scanning electron microscopy, electron back-scattered diffraction and so on. Our results showed that nearly full-dense brass could be obtained with the laser scanning speed below 200 mm/s. The optimum specimens displayed high tensile and compressive yield strength, and {110}<001> Gaussian texture. After annealing, cellular structure in the SLM specimens changed into high-density annealing twins, accompanied with weakening of the texture. The decomposition of the cellular structure resulted in a significant improvement of corrosion resistance but a decrease in tensile and compressive yield strength. Strengthening mechanism analysis demonstrated that that strengthening contribution of cellular structure was more significant than that of annealing twins. The obtained results will provide some guidelines for the production of high-performance silicon brass alloys by SLM for structural applications.