Abstract: In order to study the microstructure evolution rules in the isothermal local loading processes for large-sized titanium alloy components, the primary α-phase grain size variation processes of large-scale titanium alloy rib-web components during isothermal local loading were simulated and analyzed based on the internal variable microstructure model of TA15 titanium alloy. The local loading orders and integral loading mode were carried out as a comparison, so as to understand the microstructure evolution of the local loading. The results show that the transitional zones are affected by the transferred materials from the loading zones to unloading zones, the sizes of the primary α-phase grain after both of the loading steps are reduced, leading the sizes of the primary α-phase grains in this zone smaller than those zone away from the transitional zone. The switch of the first and second loading orders may change the quantity of transferred materials, so the loading order may affect the grain size variation processes on both sides of the die partition line. Compared with the integral loading mode, the grain size of local loading in the transitional zone is smaller. The grain size variation away from the transitional zone is almost indifference under above three loading methods.

Key words:  , large-sized titanium alloy component, isothermal local loading, internal state variable method, grain size, loading method

摘要： 为研究大型钛合金构件等温局部加载过程中的微观组织演变规律，基于TA15钛合金内变量法微观组织模型，模拟分析了大型钛合金筋板构件等温局部加载过程的初生α相晶粒尺寸变化规律，并与变换局部加载顺序及整体加载两种方式进行了对比。结果表明：过渡区因受到加载区材料跨区转移的影响，两个加载步后的初生α相晶粒尺寸均有所减小，使得该区域的初生α相晶粒尺寸小于远离过渡区区域的晶粒尺寸；先后加载顺序的转变会改变材料的跨区转移量，以致模具分区两侧的晶粒尺寸产生差异；与整体加载方式相比，局部加载过渡区的晶粒尺寸较小；在三种加载方式下，远离过渡区晶粒尺寸的差异不大。

关键词: 大型钛合金构件, 等温局部加载, 内变量法, 晶粒尺寸, 加载方式