CAREER: Controlling Austenite Stability and Response During Deformation of Advanced High Strength Steels

职业：控制先进高强度钢变形过程中的奥氏体稳定性和响应

• 批准号: 1752530
• 负责人: Kester Clarke
• 金额: $ 50万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-15 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1752530&HistoricalAwards=false
• 关键词: CAREER; Controlling; Austenite; Stability; Response

Steels are ubiquitous as structural materials, and are found in nearly every piece of transportation, shipping, construction, or mining equipment; in buildings, roads, pipelines, appliances, and in many other applications. In the past 15 years, driven by increasingly challenging fuel economy standards, sheet steels used in automotive bodies have achieved strengths that are five times those of previous alloys. Normally, increasing strength results in a compromise in ductility - the ability for a material to stretch or bend without fracture - but these new Advanced High Strength Steel (AHSS) sheets minimize the severity of this compromise. The primary way this has been achieved is by designing the microscopic structure of the steels to resist fracture, based on new understanding of how to control this structure when manufacturing steels. This Faculty Early Career Development Program (CAREER) Award supports fundamental scientific research to uncover the relationships between the processing of these steels, the microscopic structure, and their properties and performance. A broad range of deformation conditions will be studied to better understand the material response and allow the design of steels with even better properties. This will further improve the automobile structures and help meet stringent fuel economy standards, and can also be translated to other sectors to improve the efficiency and performance in many other steel applications.This work will aim to close the design loop to develop a fundamental understanding of austenite stability during thermomechanical processing (TMP) of advanced high strength steel (AHSS) alloys that use the Transformation Induced Plasticity (TRIP) mechanism to yield exceptional combinations of strength and ductility. The ability for strain-induced austenite-to-martensite transformation to suppress strain localization, and thereby produce excellent properties, is dependent on the thermal and mechanical stability of the austenite; if austenite is too stable, it will not transform during deformation, and if austenite is unstable, it will not be retained at room temperature. Current approaches to stabilize austenite focus on increasing carbon content by performing precise thermal cycles that allow diffusion of carbon from other phases to austenite. Here the research focuses on the use of deformation conditions, including strain rate, strain state, temperature, and stress state/pressure, to understand how to further control austenite stability by performing focused mechanical testing of specifically designed alloys. The understanding developed in this work will result in a science-based understanding of austenite stability in AHSS that can be incorporated into thermodynamic and mechanical materials models, and which will enable the use of Integrated Computation Materials Engineering (ICME) and Materials Genome Initiative (MGI) principles to realize advanced manufacturing and further improve the exceptional properties that can be realized in these low-alloy, low-cost materials that underpin our efforts for lightweight structures in the transportation sector and beyond. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

钢作为结构材料无处不在，几乎存在于运输、航运、建筑或采矿设备的每一件中，也存在于建筑物、道路、管道、电器和许多其他应用中。在过去的15年里，在日益具有挑战性的燃油经济性标准的推动下，汽车车身用钢板的强度是以前合金的五倍。通常情况下，提高强度会导致延性的降低--材料拉伸或弯曲而不断裂的能力--但这些新的先进高强度钢(AHSS)钢板将这种影响的严重性降到了最低。实现这一点的主要方法是设计钢的微观结构以防止断裂，这是基于对如何在制造钢时控制这种结构的新理解。该学院早期职业发展计划(Career)奖支持基础科学研究，以揭示这些钢材的加工、微观结构与其性能和性能之间的关系。将研究广泛的变形条件，以更好地了解材料的响应，并允许设计具有更好性能的钢。这将进一步改进汽车结构，帮助满足严格的燃油经济性标准，也可以推广到其他部门，以提高许多其他钢铁应用的效率和性能。这项工作的目的是结束设计循环，以基本了解先进的高强度钢(AHSS)合金在热机械加工(TMP)过程中的奥氏体稳定性，这种合金使用相变诱导塑性(TRIP)机制来产生特殊的强度和塑性组合。应变诱导奥氏体相变抑制应变局部化从而产生优良性能的能力取决于奥氏体的热稳定性和机械稳定性；如果奥氏体太稳定，它将不会在变形过程中转变，如果奥氏体不稳定，它将不会在室温下保留。目前稳定奥氏体的方法主要集中在通过执行精确的热循环来增加碳含量，从而允许碳从其他相扩散到奥氏体。这里的研究重点是使用变形条件，包括应变速率、应变状态、温度和应力状态/压力，以了解如何通过对特殊设计的合金进行重点机械测试来进一步控制奥氏体稳定性。这项工作中形成的理解将导致对AHSS中奥氏体稳定性的科学理解，这可以被纳入热力学和机械材料模型，这将使集成计算材料工程(ICME)和材料基因组倡议(MGI)原理能够实现先进制造，并进一步改善这些低合金、低成本材料中可以实现的特殊性能，这些材料支撑我们在交通部门和其他领域的轻量化结构的努力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Decoupling the Impacts of Strain Rate and Temperature on TRIP in a Q&P Steel

• DOI: 10.1007/s11837-021-05039-5
• 发表时间: 2022-01
• 期刊: JOM
• 影响因子: 2.6
• 作者: C. Finfrock;D. Bhattacharya;B. McBride;T. Ballard;A. Clarke;K. Clarke

Manipulating Retained Austenite Fraction and Stability With Controlled Chemical Heterogeneities in Q&P Steels

• DOI: 10.1007/s11661-023-07233-3
• 发表时间: 2023-10
• 期刊: Metallurgical and Materials Transactions A
• 作者: Melissa M. Thrun;Amy Clarke;Kester Clarke

Strain Rate Dependent Ductility and Strain Hardening in Q&P Steels

• DOI: 10.1007/s11661-020-06127-y
• 发表时间: 2021-01-19
• 期刊: METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
• 影响因子: 2.8
• 作者: Finfrock, Christopher B.;Thrun, Melissa M.;Clarke, Kester D.
• 通讯作者: Clarke, Kester D.

Elucidating the Temperature Dependence of TRIP in Q&P Steels Using Synchrotron X-Ray Diffraction, Constituent Phase Properties, and Strain-Based Kinetics Models

• DOI: 10.1016/j.actamat.2022.118126
• 发表时间: 2022-07
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: C. Finfrock;B. Ellyson;Ranga Jai Sri Likith;Douglas T. Smith;C. Rietema;A. Saville;Melissa M. Thrun;C. Becker;A. L. Araujo;E. Pavlina;Jun Hu;Jun-Sang Park;A. Clarke;K. Clarke

Resolving the Martensitic Transformation in Q&P Steels In-Situ at Dynamic Strain Rates Using Synchrotron X-ray Diffraction

• DOI: 10.1007/s11661-022-06788-x
• 发表时间: 2022-08
• 期刊: Metallurgical and Materials Transactions A
• 作者: C. Finfrock;B. Ellyson;C. Becker;J. Copley;K. Fezzaa;N. Parab;Tao Sun;C. Kirk;N. Kedir;Weinong W. Chen;A. Clarke;K. Clarke