Research On Microstructure And Properties Of Tin Phosphor Bronze (C5191) Alloy

At present, Tin Phosphor Bronze products are used in all kinds of hi-gh and new technology industry. In order to meet the needs of different in dustries, the requirement of mechanical performance is higher and higher, which include the material organization composition, the surface quality and dimensional accuracy, especially the mechanical properties such as te-nsile strength, yield strength. The main ways to improve the performance of Tin Phosphor Bronze alloy include:doped with other elements in the Tin Phosphor Bronze; through the electromagnetic processing to improve casting organization of Tin Phosphor Bronze; improve the heat treatment process conditions of Tin Phosphor Bronze alloy.This topic on Tin Phosphor Bronze C5191(QSn6.5-0.1) improve app-roaches such as different heat treatment process, different cold deformati-on processing and different alloy content. Then take the observation of th e microstructure and composition analysis with SEM and OES, and using electronic universal material testing machine to test mechanical properties such as yield strength, hardness, tensile strength elongation and others. E-xamining the influence of the different heat treatment process and cold d-eformation process, and different tin, phosphorus and nickel content on t -he Tin Phosphor Bronze C5191 (QSn6.5-0.1) to the organization and per-formance. The main conclusion of the experimental is:Firstly, Tin Phosphor Bronze C5191 through low temperature anneal-ing4 hinthe degree of 230℃,220℃,210℃,200℃. With the anneali-ng temperature drop, the degree of grain go to refinement, and the degr-ee of grain refinement get most completely under the degree of 20 0. Tin Phosphor Bronze C5191’s yield strength in the condition of low te-mperature annealing is higher than without it. As the annealing temperat-ure drop, yield strength and yield ratio increased, and the yield rati-o of the alloy increased to 0.95 in the 200℃ heat treatment after 4 h, but alloy elongation decreased, and the tensile strength decreased slightly.Secondly, Tin Phosphor Bronze C5191 under 200 ℃ low temper-ature annealing heat preservation through 2 h,3 h,4 h,5 h. Allo-y organize the tiny grains in heat preservation after 4 h. With alloy annealing time increasing, tensile strength and yield strength decrea-se first, and then increases and reduces in the last, but extension f-irst decreases and then increases. The yield ratio of the alloy reach-ed the highest at 200 ℃ low temperature annealing after 4 h.Thirdly, Tin Phosphor Bronze C5191 alloy take cold-rolled deformation after 4 h homogenizing annealing at 650℃. With the increase of cold deformation, the twin width and number will increase. The experiment shows that the plastic deformation can make alloy occur two different deformation mechanism which is slip and twin, and the twin is more apparent after cold rolling deformation.Fourthly, Tin Phosphor Bronze C5191 alloy take cold-rolled deformation after 4 h homogenizing annealing at 650 ℃. With the increase of cold deformation, the alloy flexural folding number is less, and the elongation decreases, but hardness and tensile strength increases. In the deformation process solute atoms, Sn and Cu, react with each other, which make alloy layer fault would decline and promote the formation of twinning. The strength and elastic limit of the tin phosphor bronze alloy after cold rolling deformation can improve by twinning deformation.Fifthly, Tin Phosphor Bronze C5191 alloy take low temperature annealing after cold deformation. Alloy internal appear a large number of solute atoms partial gathered in deformation twin area, which shows the cold deformation must go through before low temperature annealing, and it is also the premise condition to strength. It is not only provides additional energy, but also order domain within the organization, and the hardness and strength of the alloy improved after annealing.Sixthly, with the increase of Sn elements content Tin Phosphor Bronze C5191 alloy organization had not great influence, and tensile strength and yield strength of the alloy has a certain extent. But a slight drop showed after Sn content higher than 6.08%, so Sn content in the Tin Phosphor Bronze should remain at around 6.08%.Seventhly, with the increase of P element content the growth of grains in the organization of Tin Phosphor Bronze C5191 alloy are gradually inhibit, but when P content higher than 0.14% grain become larger. With the increase of P element content the hardness of alloy has a little rise, and tensile strength and yield strength are increased before they are cut. Yield ratio reached the highest when content is 0.14%. So the P content in tin phosphor bronze should remain at around 0.14%.Eighthly, with the increase of Ni element content he growth of y phase inhibited in Tin Phosphor Bronze C5191 alloy. But high Ni content can lead to precipitation hard brittle phase. With the increase of Ni element the hardness of alloy reduced after first increased, but the tensile strength and yield strength are increased in the first and then decreased. Yield ratio reached highest when Ni content is 0.151%, so the content of Ni in tin phosphor bronze should remain at around 0.151%.