直径增大速率对IN718合金环件径轴向轧制成形微观组织演变的影响  

Influence of Diameter Growth Speed on Microstructural Evolution During Radial-Axial Ring Rolling of IN718 Alloy

作　　者：唐学峰 王宝雨[2] 王新云[1] TANG Xuefeng;WANG Baoyu;WANG Xinyun(School of Materials Science and Engineering,Huazhong University of Science and Technology,Wuhan 430074,China;School of Mechanical Engineering,Beijing University of Science and Technology,Beijing 100083,China)

机构地区：[1]华中科技大学材料科学与工程学院,武汉430074 [2]北京科技大学机械工程学院,北京100083

出　　处：《航空制造技术》2020年第16期34-44,共11页Aeronautical Manufacturing Technology

基　　金：国家杰出青年科学基金(51725504)。

摘　　要：IN718合金环件径轴向轧制(Radial-axial ring rolling,RARR)成形容易出现混晶和局部晶粒粗大,导致零件无法满足航空发动机严苛的服役要求。以环件匀速长大为稳定轧制条件,给出了径轴向协同进给速度模型,并建立轧辊自适应径轴向轧制多场耦合有限元模型。应用以位错密度、再结晶分数和晶粒尺寸为内变量的统一本构模型,通过多场耦合有限元模拟研究了环件直径增大速率对IN718合金径轴向轧制成形微观组织的影响。结果表明:在保证稳定轧制的前提下,提高直径增大速率使环件平均温度升高,促进了再结晶晶粒的形核长大,使环件平均总再结晶分数增大;另一方面,提高直径增大速率缩短了轧制时间,不利于再结晶晶粒的长大,使再结晶分数减小,因而在直径增大速率超过4mm/s后环件平均总再结晶分数随之减小。Mixed crystal and local coarse grain often appeared during radial-axial ring rolling of IN718 alloy,which impeded the satisfaction to the stern service requirement of aircraft engine.This article derived the mathematic model of steady rolling condition and the synergistic radial-axial feeding of ring rolling process based on the constant ring growth speed,and established a multi-physical finite element model of radial-axial ring rolling with adaptive roller control.A unified constitutive model of IN718 alloy based on internal state variables including dislocation density,recrystallization fraction and grain size was employed to investigate the effect of diameter growth speed on the microstructural evolution of radial-axial ring rolling of IN718 alloy by finite element simulation.The results showed that under the steady rolling condition,higher average temperature could be obtained by using higher diameter growth speed,which facilitated the nucleation and growth of the recrystallized grains.Moreover,the rolling time was decreased with the increasing diameter growth speed,the fraction of recrystallization was then decreased since there was insufficient time for growth of dynamic recrystallized grains.As a result,the total fraction of recrystallization was increased at early stage and then was decreased with the increase of diameter growth speed after the diameter growth speed exceeds 4.0mm/s.

关 键 词：环件轧制 微观组织演变 IN718合金 稳定轧制 统一本构模型 

分 类 号：V263[航空宇航科学与技术—航空宇航制造工程]