Research On Materials And Processing Technology Of Aluminum Alloy Used For Bicycle Frame

Now, the most widely used Al alloy material for bicycle frame is Al alloy6061, which has following advantages:beauty, handiness, good-processability and lower production costs. However, tensile strength of Al alloy6061is generally lower than300MPa, so it is difficult to meet high standards because of lower reliability of safety. According to the different requirements of high-end bicycle frame, Al-Mg-Si series Al alloy1#,2#, and3#were designed to solve this problem in this paper. Means of microstructure analysis, tensile test and reliability test of bicycle frame were used to study microstructure and property characteristics of those three Al alloy, especially the horizontal force reliability of frame. And this paper also focuses on the problem in manufacturing process of Al alloy frame to research heat process of Al alloy frame.Tensile strength and elongation of Al alloy1#are330MPa and14.1%. Road frame made of Al alloy1#can pass the reliability test in EN14766standard. It was found found that microelements Zr and Er in Al alloy1#had effects on grain refinement and dispersion strengthening, thus improving mechanical properties and frame reliability.Elongation of Al alloy2#can reach15.8%, while the tensile strength is still up to370MPa. MTB(Mountain Terrain Bicycle) frame made of Al alloy2#can pass the reliability test in EN14766standard. Al alloy2#casting rods has large tendency of central crack. To prevent the central crack, following measures are effective in casting production:reduce the refining temperature of Al alloy2#to725±735℃, meanwhile, control the Al liquid height less than250mm in refining process; reduce casting temperature to725±735℃, meanwhile, increase the downward speed of casting tray to130-140mm/min; reduce the pressure of cooling water to0.14～0.16MPa.Al alloy3#can reduce the weight of MTB frame from1800g to1450g, while ensuring that the frame can past the reliability test in EN14766standard. The effects of solution temperature, solution time, aging temperature and aging time on mechanical properties of Al alloy3#after T6treatment were investigated by orthogonal experiment. T6treatment process for good mechanical properties is510℃×3h, and then170℃×18h. Tensile strength of Al alloy3#after that T6treatment can reach403MPa, meanwhile the elongation is still up to16.4%.