Metallurgical Aspects of Deformation Processing

变形加工的冶金方面

• 批准号: RGPIN-2016-03731
• 负责人: Jonas, John
• 金额: $ 3.86万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=654800
• 关键词: Metallurgical; Aspects; Deformation; Processing

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).**

拟议的研究完全集中于高温变形，有五个子部分：***1。 奥氏体相场高温下奥氏体的动态转变。 将研究这一新发现机制的以下方面：i）压力对变异选择的影响； ii) 成分对临界应变和铁素体体积分数的影响； iii) 转变过程中间隙和替代划分的特征； iv) 魏德曼组织铁素体聚结并再转变为奥氏体； v) 动态转变的热力学。 ***2. Ti 和 Zr 合金的动态转变。 麦吉尔大学最近证明钛和锆合金容易发生动态转变。 在铁素体合金中，变形会提高 Ae3，而在六方材料中，变形会降低 β 转变。 这种转变遵循伯格斯关系，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，但有待确定。 其中包括热力学背景以及微观结构、纹理和成分效应。***3。 镁和钛合金中的孪晶、变体选择和动态应变时效。 在初级、二级和三级孪生过程中，将继续研究菌株适应对变体选择过程的作用。 特别令人感兴趣的是在剪切带附近发生的调节以及负利率敏感性对此过程的影响。 另一方面涉及与稀土和常规溶质相关的动态应变老化。 其目的是能够使用较便宜的合金元素（例如钙）生产所需的“稀土”织构。 将确定并探索实现这一目标的机制。***4． 扭转测试力学及其在热轧模拟中的应用。 Hencky 应变继续用于扭转等剪切实验的分析，并且仍然是一个有争议的话题。 申请人将通过澄清使用 Hencky 菌株合理的案例来为这场辩论做出贡献。 将对带钢（短道次时间）和板材（长道次时间）轧机计划进行模拟。 明确动态变换在工业轧制中的作用，并需要修改跳动表模型以考虑动态变换的影响。 ***5. 连续和不连续动态重结晶。 钢材加工的精确控制依赖于对静态和动态再结晶的详细了解。 我们将继续在这一重要领域开展研究，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。**