Metallurgical Aspects of Deformation Processing

提出的研究完全集中在高温变形上，分为五个部分：***1。高温奥氏体相场中奥氏体的动态转变。这一新发现的机制将从以下几个方面进行研究：1)胁迫对变异选择的影响；Ii)成分对临界应变和铁素体体积分数的影响；Iii)转换过程中的间隙和替代划分特征；ⅳ)Widmanstätten铁素体聚并再转变为奥氏体；v)动态变换热力学。* * * 2。Ti和Zr合金的动态相变。Ti和Zr合金最近在麦吉尔大学被证明易受动态转变的影响。而在铁素体合金中，变形提高了Ae3，在六角形材料中，变形降低了β横截面。这种转变遵循伯格关系，因此与适用于钢的位移机制不同。这些材料的动态转变机制尚不清楚，有待确定。这包括热力学背景以及微观结构、纹理和成分效应。Mg和Ti合金的孪生、变异选择和动态应变时效。菌株调节在变异选择过程中的作用将在一级、二级和三级孪生期间继续进行研究。特别令人感兴趣的是在剪切带附近发生的调节以及负速率敏感性对这一过程的影响。另一个方面涉及稀土和常规溶质的动态应变时效。这样做的目的是使用更便宜的合金元素（如Ca）来生产理想的“稀土”纹理。将确定和探索允许实现这一目标的机制。扭转试验力学及其在热轧模拟中的应用。亨基应变继续用于分析剪切实验，如扭转，仍然是一个有争议的话题。申请人将通过澄清使用亨基菌株是合理的情况来促进这场辩论。将对带钢（短间隔时间）和中板（长间隔时间）轧机计划进行模拟。本文将阐明动态变换在工业轧制中的作用，以及修改跳动表模型的必要性，以考虑动态变换的影响。* * * 5。连续和不连续动态再结晶。钢加工的精确控制依赖于对静态和动态再结晶的详细了解。在这一重要领域将继续开展研究，更详细地研究连续动态再结晶在多向锻造和其他严重塑性变形（SPD）途径中的作用

The research proposed is focused entirely on high temperature deformation, with five sub-components:***1. Dynamic Transformation of Austenite at Temperatures High in the Austenite Phase Field. The following aspects of this newly discovered mechanism will be investigated: i) effect of stress on variant selection; ii) effect of composition on critical strain and ferrite volume fraction; iii) characteristics of interstitial and substitutional partitioning during transformation; iv) coalescence of Widmanstätten ferrite and retransformation to austenite; and v) thermodynamics of dynamic transformation. ***2. Dynamic Transformation of Ti and Zr Alloys. Ti and Zr alloys have recently been shown at McGill to be susceptible to dynamic transformation. While in ferritic alloys, deformation raises the Ae3, in the hexagonal materials, deformation lowers the beta transus. This transformation follows the Burgers relation and is thus unlike the displacive mechanism that applies to steel. The mechanisms of dynamic transformation in these materials are unknown and will be determined. These include the thermodynamic background as well as the microstructural, textural and compositional effects.***3. Twinning, Variant Selection and Dynamic Strain Aging in Mg and Ti Alloys. The role of strain accommodation on the variant selection process will continue to be investigated during primary, secondary and tertiary twinning. Of particular interest is the accommodation taking place in the vicinity of shear bands and the effects of negative rate sensitivity on this process. Another aspect concerns the dynamic strain aging associated with both rare earth and conventional solutes. This has the aim of enabling the production of desirable "rare-earth" textures using less expensive alloying elements such as Ca. The mechanisms that permit this to be achieved will be identified and explored.***4. Mechanics of Torsion Testing and Application to Simulation of Hot Rolling. The Hencky strain continues to be employed in the analysis of shear experiments such as torsion and remains a controversial topic. The applicant will contribute to this debate by clarifying the cases where use of the Hencky strain is justified. Simulations will be carried out of both strip (short interpass time) and plate (long interpass time) mill schedules. The role of dynamic transformation in industrial rolling will be clarified together with the need to modify runout table models so as to take the effect of dynamic transformation into account. ***5. Continuous and Discontinuous Dynamic Recrystallization. The accurate control of steel processing relies on a detailed understanding of static and dynamic recrystallization. Research will continue to be carried out in this important area, with more detailed examinations of the role of continuous dynamic recrystallization in multi-directional forging and other avenues of severe plastic deformation (SPD).**