Ti6554钛合金双道次热挤压宏微观演化的有限元模拟与试验研究  

Finite element simulation and test study on macro-micro evloution of Ti6554 titanium alloy by two-pass hot extrusion

作　　者：刘斌[1] 武川 周宇杰 LIU Bin;WU Chuan;ZHOU Yu-jie(National-Local Joint Engineering Laboratory of Intelligent Manufacturing Oriented Automobile Die&Mould,Tianjin University of Technology and Education,Tianjin 300222,China;CITIC Heavy Machinery Co.,Ltd.,Luoyang 471003,China)

机构地区：[1]天津职业技术师范大学汽车模具智能制造国家地方联合工程实验室,天津300222 [2]中信重工机械股份有限公司,河南洛阳471003

出　　处：《塑性工程学报》2022年第8期83-95,共13页Journal of Plasticity Engineering

基　　金：国家自然科学基金面上项目(52075386);中国博士后科学基金面上项目(2020M672309);陕西省高性能精确成形技术与装备重点实验室开放课题(PETE2019KF02);天津市教委科研项目(2020KJ107)。

摘　　要：通过热挤压试验和有限元模拟研究了Ti6554钛合金双道次挤压宏观变形和微观组织演化规律,并进行优化获得了最优挤压工艺参数。首先,基于热压缩试验建立了材料热挤压变形本构方程、动态再结晶动力学模型和晶粒长大模型。其次,基于Deform-2D软件建立了材料双道次挤压宏微观耦合的有限元模型,研究了挤压比(13.04、10.56和8.73)、预热温度(890、940和990℃)和挤压速度(35、45和55 mm·s^(-1))对棒材的温度场、等效塑性应变场和晶粒尺寸的影响,并通过挤压试验进行了模型验证。最后,采用Design-Expert建立了挤压工艺参数与平均晶粒尺寸标准差、体积分数标准差和挤压力之间的响应面模型,采用Matla遗传算法进行多目标优化,获得了最优挤压工艺(挤压比8.73、挤压速度52 mm·s^(-1)、预热温度913℃)。采用此工艺对Ti6554钛合金进行了热挤压试验,并对挤压得到的棒料试样进行金相观察,结果表明,晶粒破碎效果较好,晶粒尺寸均匀性提高。The law of macro deformation and microstructure evolution of Ti6554 titanium alloy in two-pass hot extrusion was studied by hot extrusion tests and finite element simulation,the optimization was carried out and the optimal extrusion parameters were obtained.Firstly,the constitutive equation,dynamic recrystallization dynamic model and grain grow model were established based on the hot extrusion tests.Secondly,the macro and micro coupling model of two-pass hot extrusion of the material was established based on Deform-2D software,the effect of extrusion ratio(13.04,10.56 and 8.73),preheating temperature(890,940 and 990℃)and extrusion speed(35,45 and 55 mm·s^(-1))on the temperature field,equivalent plastic strain field and the grain size of bars were studied,and the model verification was carried out by extrusion tests.Finally,the response surface model between the extrusion process parameters and the standard difference of average grain size,the standard difference of volume fraction,and the squeezing pressure was established using Design-Expert,and the multi-objective optimization was carried out using the Matla genetic algorithm,and the optimal extrusion parameters(extrusion ratio of 9.47,extrusion speed of 55 mm·s^(-1) and preheating temperature of 913℃)were obtained.The hot extrusion tests were carried out on Ti6554 titanium alloy using the optimal process,and the metallographic observation of the extruded bars samples was carried out.The results show that the grain crushing effect is better and the grain size uniformity is improved.

关 键 词：Ti6554钛合金 棒料热挤压 有限元模拟 多目标优化 响应面法 

分 类 号：TG376.2[金属学及工艺—金属压力加工]