| Ti6554 is a kind of sub-stable high strength and high toughness ? titanium alloy developed by Baoti Group in recent years,which can be used as spring material.With the development of aviation,aerospace and other industries,there is an urgent need for higher structural benefits of titanium alloy materials,so high performance titanium alloy springs have become a hot research topic at home and abroad.It is of great significance to study its plastic processing and heat treatment process for the popularization and application of the alloy.In this paper,the rolling process of Ti6554 alloy rod and wire and the solid solution and aging heat treatment process of the alloy wire are studied.By adjusting the rolling heating temperature,solid solution and aging treatment temperature,the effects of deformation temperature on the rolling width and microstructure of alloy rod and wire,as well as the effects of solid solution and aging treatment temperature on the microstructure and mechanical properties of alloy wire were studied.The specific results are as follows:1.The effect of rough rolling temperature on the width expansion coefficient and microstructure of the alloy is remarkable.The heating temperature suitable for rough rolling of the alloy is 900 ?.When the alloy is heated and rolled at 950 ?,the width spread coefficient of the alloy is small,which is 0.12~0.5,and each pass is not filled.After rolling,the microstructure is coarse,accompanied by secondary recrystallizing and tertiary recrystallization.when the rolling temperature is heated at 900 ?,the width spread coefficient is 0.25~0.70,and the filling degree of each pass is about 90%.After rolling,the microstructure is uniform and the grain size is controlled effectively.2.The continuous rolling temperature is also an important technological condition affecting the alloy width,and the heating temperature suitable for the alloy continuous rolling is 800 ?.Similar to the results of rough rolling test,the width spread coefficient is 0.27~0.78 and the filling degree of each pass is low when heated at 880 ?.When heated at 800 ?,the width spread coefficient is 0.32~0.80,the filling degree of each pass is about 90%,and the dimensional tolerance and ellipse of the finished wire blank are good.3.The solid solution heating system before aging is the key technologicalparameter affecting the solid solution microstructure and mechanical properties of the alloy.When the solid solution is below the phase transition point,the primary ? phase precipitates in the alloy.With the increase of solid solution temperature,the primary ? phase with strengthening effect decreases,the strength of the alloy decreases and the plasticity increases.When the phase transition point is above the solid solution,the primary ? phase is completely transformed into ? phase.With the increase of solid solution temperature,the grain size of the alloy increases,while the strength and plasticity of the alloy decrease.4.Aging temperature is also an important process parameter affecting the microstructure and tensile properties of the alloy.With the increase of aging temperature,the amount of ? phase precipitated by aging increases,and the local enrichment size increases.At the same solid solution temperature,the tensile and yield strength of the alloy decreases with the increase of aging temperature,and the elongation after break increases with the increase of aging temperature.5.Solid solution temperature and aging temperature are the main process control techniques affecting the solid solution aging properties of the alloy.Ti6554 alloy is different from other ? titanium alloys in solid solution above the phase transformation point to obtain better comprehensive mechanical properties.The alloy needs solid solution heat treatment below 20 ? below the phase transition point,and good comprehensive mechanical properties can be obtained after aging at 500 ? 520 ?. |
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