AHSS Through Paraequilibrium Carbon Partitioning and Austenite Stabilization

AHSS 通过准平衡碳分配和奥氏体稳定化

• 批准号: 0727583
• 负责人: Gary Michal
• 金额: --
• 依托单位: Case Western Reserve University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0727583&HistoricalAwards=false
• 关键词: AHSS; Through; Paraequilibrium; Carbon; Partitioning

Funding provided by this grant will be used to develop a new generation of advanced high strength steel (AHSS) exhibiting exceptional mechanical properties achieved by creating microstructures comprised of martensite and austenite. Determining the maximum amount of austenite that can be retained in relatively lean alloys by fully exploiting the phenomenon of stabilization will be a central goal of the work. A double stabilization processing scheme will be employed. Candidate alloys will be fully austenitized after cold rolling and cooled rapidly enough to circumvent the bainite transformation in route to an initial hold temperature. The first stage of stabilization will occur at that point when the steel is briefly held just above its Ms temperature. The steel then will be cooled to its final quench temperature chosen to cause a prescribed volume fraction of the austenite to transform to martensite. Additional stabilization will occur when the steel is aged at a higher temperature to allow partitioning of carbon from the martensite into the austenite under paraequilibrium, carbide-free conditions. This second stabilization will enable the austenite to have the required resistance to transformation to martensite when the steel is finally cooled to room temperature. The broader impact of the project is the development of a new generation of steel for advanced engineering designs. To realize a viable new structural material a high volume fraction of austenite with optimized stability must be obtained within the constraints of a carbon content low enough to not severely compromise weldability, alloy levels that do not greatly increase the cost of the steel and a processing path consistent with current sheet steel production practice. The strength and ductility combinations that will become available are intended for the production of lighter weight components with increased resistance to fracture enabling greater energy savings and margins of safety.

这笔赠款提供的资金将用于开发新一代先进高强度钢(AHSS)，这些钢通过创建由马氏体和奥氏体组成的微结构而显示出优异的机械性能。通过充分利用稳定现象来确定相对贫化的合金中可以保留的最大奥氏体量将是这项工作的中心目标。将采用双稳定处理方案。候选合金在冷轧后将完全奥氏体化，并以足够快的速度冷却，以避免在达到初始保持温度的过程中发生贝氏体转变。稳定的第一阶段将发生在钢被短暂保持在略高于其ms温度的点上。然后，钢将冷却到其最终的淬火温度，以使规定体积分数的奥氏体转变为马氏体。当钢在更高的温度下时效时，将发生额外的稳定，以允许在准平衡、无碳化物的条件下将碳从马氏体分配到奥氏体中。当钢最终冷却到室温时，这种第二次稳定化将使奥氏体具有所需的向马氏体转变的抗力。该项目更广泛的影响是为先进的工程设计开发新一代钢材。为了实现一种可行的新结构材料，必须在碳含量低到不会严重影响焊接性、合金化水平不会大幅增加钢的成本以及符合当前薄板生产实践的工艺路线的约束下，获得具有优化稳定性的高体积分数奥氏体。即将上市的强度和延展性组合旨在生产重量更轻的部件，具有更高的抗断裂能力，从而实现更大的能源节约和安全裕度。