Characterization and physical based modeling of the bake-hardening effect in dual-phase steels: Development of a through-process modeling approach for the material behavior

双相钢烘烤硬化效应的表征和基于物理的建模：开发材料行为的全过程建模方法

• 批准号: 263894884
• 负责人: Professor Dr.-Ing. Heinz Palkowski
• 金额: --
• 依托单位: Institut für Werkstoffwissenschaft und Werkstofftechnologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/263894884?language=en
• 关键词: Characterization; physical; based; modeling; bake

The automotive industry is driven by the continuous challenge to improve safety and fuel economy requirements for future vehicles. This implies, however, the need for improved steel grades to meet higher standards for automotive structural and safety parts. Dual-phase (DP) steels are widely used in automotive applications because they combine high yield strength and good formability at moderate production costs. Recently, it has been proposed to use the bake-hardening (BH) effect as an additional strengthening mechanism in DP steels to benefit from increased yield strength. This strengthening occurs during paint baking of the car body after sheet forming operations and car body assembly. In automotive engineering, computer simulations of material behavior have become an integral part in the product and process development. For the applicability of these simulations in industrial practice it is essential to have models provided which are able to predict the material behavior during each step of processing. With this through-process modeling approach, computer simulations can be used to adjust the process parameters in each process step in order to achieve the final mechanical properties. The project aims at developing new physical-based approaches for the BH effect in DP steels. This will be achieved through a series of advances in experimental characterization of the BH effect in DP steels combined with theoretical modeling. The experimental investigations will focus on the different factors affecting the BH effect in DP steels. Explicitly, on industrially produced DP steels different microstructure characteristics (e.g. grain size, martensite volume fraction and morphology), pre-loading conditions (uni-axial, bi-axial and plane strain), and ageing conditions will be investigated down to the nanoscopic scale. The experimental results from the planned experiments are to be used in the theoretical modeling of the BH effect in DP steels which will be accomplished in cooperation with TU Wien. The theoretical modeling will cover the range from the nanoscopic to the macroscopic scale. For the physically-based modeling of the static strain-ageing kinetic in ferrite and the tempering effects in martensite, a new theoretical approach will be employed. The physical-based internal-state-variable (ISV) approach will be utilized for the modeling of microstructure evolution as well as for the flow-stress modeling. Moreover, a model for stress-strain curves describing the yield-point phenomenon will be developed. Finally, the integrated outcome of the proposed work will result in an advanced software tool for through-process modeling of the BH effect in DP steels.

汽车行业不断面临着提高未来车辆安全性和燃油经济性要求的挑战。然而，这意味着需要改进钢材等级，以满足汽车结构和安全部件的更高标准。双相（DP）钢具有屈服强度高、成形性能好、生产成本低等优点，在汽车领域得到了广泛的应用。最近，有人提出使用烘烤硬化（BH）效应作为DP钢的额外强化机制，以受益于屈服强度的提高。这种强化发生在板材成型操作和车身组装后的车身烤漆过程中。在汽车工程中，材料性能的计算机模拟已成为产品和工艺开发中不可或缺的一部分。为了使这些模拟应用于工业实践，必须提供能够预测材料在每一步加工过程中的行为的模型。通过这种全过程建模方法，计算机模拟可以用于调整每个工艺步骤中的工艺参数，以获得最终的机械性能。该项目旨在为DP钢中的BH效应开发新的基于物理的方法。这将通过DP钢中BH效应的一系列实验表征与理论建模相结合来实现。实验研究的重点是影响DP钢BH效应的不同因素。明确地说，在工业生产的DP钢上，不同的微观结构特征（如晶粒尺寸、马氏体体积分数和形貌）、预加载条件（单轴、双轴和平面应变）和时效条件将被研究到纳米尺度。计划实验的实验结果将用于DP钢中BH效应的理论建模，该模型将与维也纳工业大学合作完成。理论建模将涵盖从纳米尺度到宏观尺度的范围。对于铁素体静态应变时效动力学和马氏体回火效应的物理建模，将采用一种新的理论方法。基于物理的内状态变量（ISV）方法将被用于微观结构演化的建模以及流动应力的建模。此外，还将建立一个描述屈服点现象的应力-应变曲线模型。最后，所提出的工作的综合结果将产生一个先进的软件工具，用于DP钢中BH效应的全过程建模。