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arXiv 2211.09720cond-mat.mtrl-sci
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马氏体硬化行为在双相钢局部与全局塑性悖论中的关键作用

On the critical role of martensite hardening behavior in the paradox of local and global ductility in dual-phase steels

V. Rezazadeh, R. H. J. Peerlings, J. P. M. Hoefnagels, M. G. D. Geers

发表信息：
European Journal of Mechanics - A/Solids. (2023) 105152
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AI总结：

针对双相钢全局塑性与局部塑性存在的悖论，本文通过微观力学统计研究发现马氏体硬化行为是核心影响因素，相力学性能差异的提升会增强全局塑性但削弱局部塑性，为研发兼具两类塑性的钢材提供了关键方向。

摘要：

文献中的实验发现表明，强度与成分相同但微观结构不同的双相钢（DP steels），在颈缩控制或损伤控制的塑性试验中表现出不一致的变化趋势。这一现象的一个特例在成形领域被称为双相钢的切边失效或边裂问题。研究观察到，全局塑性较好的微观结构在切边处容易发生早期损伤，而塑性相对较差的双相钢在这类边缘的局部变形作用下表现更优。本文从微观力学角度开展了系统的统计研究，以分析这一悖论。所得结果定性验证了上述实验观测，并可对其作出如下解释与合理化说明：要获得更高的颈缩控制型塑性（即全局塑性），必须增大铁素体与马氏体之间的力学性能差异。由于马氏体具有极高的初始硬化速率且快速饱和，马氏体塑性的激活会导致微观结构发生早期颈缩，因此应予以避免；较高的相力学性能差异恰好能起到这一作用。但与此同时，较高的相力学性能差异对局部塑性不利。微观结构中更高的异质性会产生更大的局部塑性应变和三轴应力，进而引发早期损伤。因此，在双相钢中，提升全局塑性可能以降低局部塑性为代价，反之亦然。马氏体硬化行为是主导这一现象的核心因素，也因此成为研发兼具两类塑性优势的高性能钢材的关键。

英文摘要：

Experimental findings in the literature reveal that DP steels with identical strength and composition, but different microstructures, exhibit inconsistent trends under either necking-controlled or damage-controlled ductility tests. A special case of this phenomenon is referred to in the forming community as the cut-edge failure or edge cracking issue of DP steels. It is observed that globally ductile microstructures are prone to premature damage at cut edges while a comparatively less ductile DP steel performs better under the locally applied deformation at such edges. In this paper, a systematical statistical study is conducted to analyse this paradox from a micromechanical point of view. The obtained results qualitatively confirm the experimental observations and allowed us to explain/rationalize them, as follows. To reach a higher necking-controlled ductility, i.e. global ductility, the mechanical contrast between ferrite and martensite must be increased. Since martensite reveals a very high initial hardening and fast saturation, activation of martensite plasticity will lead to early necking in the microstructure and should therefore be avoided; a high mechanical phase contrast has this effect. However, at the same time a higher mechanical phase contrast is detrimental for the local ductility. More heterogeneity in the microstructure causes the generation of higher local plastic strains and triaxial stresses which leads to early damages. Therefore, in DP steel, increasing the global ductility may come at the expense of decreasing local ductility, and vice versa. The martensite hardening behavior is the main factor governing this phenomenon, and therefore also constitutes the key to processing improved steels that combine the best of both.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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