中文摘要：

基于铸坯的环件径轴向辗轧成形新技术面临的瓶颈问题，对坯料铸态组织的演变规律与合理控制进行研究。对某环件双向轧制，铸坯的尺寸将决定变形程度和径、轴向的变形量分配，从而对最终环件的组织起着至关重要的作用。该文基于ABAQUS平台，建立了42CrMo钢铸坯环件径轴向热辗轧宏微观耦合有限元模型；采用一种基于轧比 K和径轴向变形量分配比tanα的坯料尺寸设计方法，针对同一环件的轧制过程，设计具有不同 K和tanα值的不同尺寸的多个环坯，模拟不同铸态42CrMo坯料尺寸下环件径轴向辗轧过程组织的演变规律。结果表明，随着 K值增大，环件动态再结晶程度增加，平均晶粒尺寸减小且分布逐渐均匀；随着 tanα值增大，环件上下端面区域动态再结晶程度增大，平均晶粒尺寸减小，沿环件轴向平均晶粒尺寸分布逐渐不均匀，而内外表面区域动态再结晶程度减小，平均晶粒尺寸增大，沿环件径向平均晶粒尺寸分布逐渐均匀。

英文摘要：

Based on the main bottleneck question for the development of the new technology of radial-axial ring rolling based on in-got blank , the evolution rules and reasonable control of the cast microstructure of the blank have been studied . For the bidirec-tional rolling of a certain ring part , the blank size determines the deformation degree and the distribution of reductions along radial and axial directions ,thus it plays a crucial role on the final structure of the rolled ring .In this paper ,we first established a cou-pled macro-micro FE model of radial-axial ring rolling process based on 42CrMo ingot blank under ABAQUS software environ-ment ,then designed multiple ring blanks for an identical ring part using a blank sizes design method based on rolling ratio （K） and the ratio of deformations （tanα） in the radial and axial directions ,and lastly numerically revealed the evolution rules of micro-structure during radial-axial ring rolling process under different blank sizes . The results demonstrate that ：1） with the increase of K ,the recrystallization percentages increase , the average grain sizes decrease and distribute more uniformly ;2） with the in-crease of tanα, the average grain sizes decrease in the ring top and bottom regions with increased recrystallization percentages , and distribute more unevenly along the axial direction ;while in the inside and outside region , the average grain sizes increase and distribute more uniformly along the radial direction .