Investigation of microstructure, machinability, and mechanical properties of new-generation hybrid lead-free brass alloys

Abstract In this study, hybrid alloys were obtained by casting method with alloy elements and additive such as Si and MoS2, which can be used instead of lead, and compared with Ecobrass and free cutting brass samples used in the market in terms of microstructure, mechanical, and machinability properties. The microstructures of lead-free hybridized brass consists of alpha, beta, and intermetallic compound which were confirmed by the results of X-Ray Diffraction analysis and Scanning Electron Microscopy-Energy Dispersive Spectroscopy. The hardness values of the beta phase in the microstructure are between 180 and 220 Vickers hardness. It has been observed that increasing the amount of beta prime phase also increases the hardness. The machinability of samples was evaluated in terms of surface roughness and chip formation. Chips obtained from samples after machining process were categorized according to ISO 6385-G1 standard. Chip morphologies were examined under optic microscope and scanning electron microscope. The surface roughness value of samples with MoS2 additives was found to be the lowest due to its lubricity effect. Moreover, morphologies, distribution of phases, and intermetallic compounds in the microstructure are found to have a great impact on the machinability and ultimate tensile strength.