多向锻造纯钨形变储存能及动态再结晶行为分析

Deformation Stored Energy and Dynamic Recrystallization Behavior of Pure Tungsten Processed by Multiple Directional Forging

对纯钨烧结体进行多向锻造试验,运用OM和DSC分析了纯钨多向锻造组织演化规律及形变储存能的变化,结合XRD、EBSD对纯钨形变储存能的来源及动态再结晶行为进行了研究。结果表明:多向锻造后纯钨内部孔隙明显减少,热变形过程中的动态再结晶导致晶粒显著细化,变形后保留在晶粒及亚晶内部的高密度位错结构导致形变储存能的增加,再结晶晶粒主要沿能量较高的晶界及晶界交汇处分布,其动态再结晶机制为形变诱导晶界迁移机制与亚晶粗化及晶粒机械破碎的混合机制,多向锻造后纯钨再结晶温度基本不变,材料热稳定性有所提高。

Microstructure evolution and change of deformation stored energy of sintered pure tungsten during multi-directional forging were investigated by OM and DSC. The source of deformation stored energy and dynamic recrystallization behavior of pure tungsten were studied by XRD and EBSD. The results indicate that dynamic recrystallization during hot deformation leads to remarkable grain refining with porosity significantly decreasing. The high-density dislocation structure that remains in the grains and subgrains results in an increase in stored energy of deformation after deformation. There are quantities of recrystallized grains distributed along the higher energy zone in grain boundaries and grain boundary intersection. The mechanism of dynamic recrystallization is the mixture of deformation induced grain boundary migration mechanism with subgrain coarsening and mechanical fragmentation of grains. The recrystallization temperature of pure tungsten is unchanged substantially, and with thermal stability is increased after multiple directional forging.