Developed A High-strength Cutting Zinc Alloy Extruded Profiles

For the purpose of replacing the expensive copper with zinc, which is cheaper and more easily got, a kind of zinc based alloy with high strength and good cutting property is developed in the present investigation, to replace the brass HPb59-1 using as watch belt, belt fastener, structures in bathroom and so on.By comparing the cutting and mechanical performance of the six self-prepared zinc alloys, just one alloy(named ZE-1 zinc alloy) which is of excellent comprehensive properties and can reach the requirement of the users, is particularly selected, and the following research focuses on this alloy only. By the means of drilling test, hot compression simulation, numerical simulation of the extruding process, structures observation and mechanical measurement, the properties and structures of ZE-1 zinc alloy are investigated. The main results are as follows:(1) Proper additions of rare earth(Re) elements can improve the cutting performance of the zinc-based alloy obviously, and can increase its strength and hardness ;(2) The flow stress of ZE-1 zinc alloy in thermal compression deformation decreases with the temperature increasing, and increases with raising the strain rate; The Zener-Hollomon parameter mode is adopted to describe the flow stress of ZE-1 zinc alloy during hot compression deformation;(3) By FEM analysis and producing test, the extrusion forming of ZE-1 zinc alloy is realized, and feasible extrusion process of this alloy is obtained as: extrusion temperature 350℃, extrusion ratio 17.5 (with bi-orifice die) and extrusion rate at the die exit 20mm/s. The tensile strengthσ_b of the extruded profile is 375 MPa, the elongationδis 2%;(4) A kind of heat treatment process to improve the strength and hardness of ZE-1 zinc alloy is obtained as: holding at 250℃for 30 minutes. The tensile strengthσ_b of the heat treated sample is 408 MPa, the elongationδis 3.3%;(5) Compared with extrusion state, the corrosion resistance of ZE-1 zinc alloy after the above heat treatment is slightly decreased, but there is no obvious inter-crystalline corrosion take place after static corrosion in 5% NaCl, in nether extrusion state nor heat treatment state.