Mg-3Y合金大应变量轧制过程中的孪生辅助动态再结晶及组织演变

Twinning Assisted Dynamic Recrystallization and Related Microstructure Evolution During Large Strain Rolling of Mg-3Y Alloy

摘要:

采用预挤压加单道次大应变量热轧制的方法制备了Mg-3Y（质量分数，%）合金板材。并研究了大应变量轧制过程中不同孪晶类型对合金动态再结晶（DRX）及组织演变的影响。结果表明，在挤压比为8:1的预挤压过程中，合金内部发生了几乎完全的动态再结晶。而在接下来的大应变量热轧制过程中，孪生变形尤其是{101}压缩孪晶及{101}-{102}双孪晶在协调合金的塑性应变中发挥了重要作用。此外，大量动态再结晶在压缩孪晶及双孪晶内部发生，并扩展到非孪晶区域，有效缓解了轧制过程中的内应力集中。上述2个过程对提高合金在大应变量轧制中的成形性均起到了促进作用。

Abstract:

The Mg-3Y (wt%) alloy sheet was fabricated by pre-extrusion and subsequent single-pass large strain hot rolling process. The influences of different twinning types on dynamic recrystallization (DRX) and grain structure evolution during large strain hot rolling were investigated. Results show that the alloy undergoes nearly complete DRX during pre-extrusion processing under a low extrusion ratio of 8:1. During subsequent large strain hot rolling processing, deformation twinning, especially the {101} compres-sion and {101}-{102} double twinning, plays an important role in plastic strain accommodation. Moreover, the compression twin and double twin assisted DRX occurs extensively within the grains, and the recrystallization region is extended from the twin interior towards non-twinned regions, greatly relieving the internal stress. Both of processes above promote the formability of the alloy during large strain hot rolling processing.