大变形热轧制备超细晶TC4钛合金的组织与性能

摘要

The ultrafine-grained TC4 titanium alloy was produced by severe hot rolling for 2-4 passes at start rolling temperature of 1 100 ℃ with 70 t rolling mill,and the effects of rolling reduction(60%-90%)on the microstructure and mechanical properties of the alloy were investigated.The results show that the lamellar structures ofαandβphases in TC4 titanium alloy were deformed to ultrafine structures by dynamic recrystallization during hot rolling,and dislocations were retained in the microstructures because of the incompletion of dynamic recrystallization.With the reduction increasing,the number of ultrafine grains increased,the grain size decreased, the tensile strength of the alloy increased,the plasticity was kept well,and the tensile fracture occurred by ductile mode.After 90% severe hot rolling,the high-strength high-ductile ultrafine-grained TC4 titanium alloy was produced,with average grain size of 150 nm,tensile strength of 1 135 MPa and elongation above 9%.%在70 t轧机上,以1100 ℃为开轧温度,采用2~4道次大变形轧制方式制备超细晶TC4钛合金,研究了变形量(60%~90%)对该合金组织和性能的影响.结果表明:TC4钛合金中的α和β相片层状组织在热轧过程中因动态再结晶被分解成超细晶组织,由于动态再结晶不完全,组织中存在残留位错;随着变形量增加,超细晶的数量增加且晶粒尺寸减小,合金强度增大,且塑性保持良好,拉伸断裂方式均为韧性断裂;经变形量为90%的大变形热轧后,得到了高强高韧超细晶 TC4钛合金,其平均晶粒尺寸约150 nm,抗拉强度达1135 MPa,伸长率超过9%.