New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols
New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols
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DOI：
10.3390/met10010018
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发表时间：
2019-12
期刊：
影响因子：
2.9
通讯作者：
A. Khosravani;C. Caliendo;S. Kalidindi
中科院分区：
文献类型：
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作者：
A. Khosravani;C. Caliendo;S. Kalidindi
在这项研究中，最近建立的多分辨率球形压痕应力-应变协议已被用于获得新的见解的微观结构的变化，发生在双相（DP）钢的加工过程中。这是通过利用不同半径的压头来实现的，以便可以在宏观尺度（反映样品的整体性质）和微观尺度（反映组成相的性质）上评估机械响应。更具体地说，九个不同的热机械加工条件，涉及不同的组合的临界区退火温度和烘烤硬化后，不同量的冷加工进行了研究。除了证明压痕协议的巨大好处，以高吞吐量的方式评估每个样品内的变化和不同材料长度尺度的样品之间的变化，测量提供了几个新的见解在合金加工过程中发生的微观结构变化。特别地，压痕测量表明，与从750 ° C淬火相比，当从810 °C淬火时，马氏体相的强度降低约37%，而铁素体相的强度保持大致相同。此外，在10%的厚度减小和烘烤硬化步骤期间，马氏体相的强度由于回火而显示出小的降低，而铁素体的强度通过静态时效增加了约50%。
In this study, recently established multiresolution spherical indentation stress–strain protocols have been employed to derive new insights into the microstructural changes that occur during the processing of dual-phase (DP) steels. This is accomplished by utilizing indenter tips of different radii such that the mechanical responses can be evaluated both at the macroscale (reflecting the bulk properties of the sample) and at the microscale (reflecting the properties of the constituent phases). More specifically, nine different thermo-mechanical processing conditions involving different combinations of intercritical annealing temperatures and bake hardening after different amounts of cold work were studied. In addition to demonstrating the tremendous benefits of the indentation protocols for evaluating the variations within each sample and between the samples at different material length scales in a high throughput manner, the measurements provided several new insights into the microstructural changes occurring in the alloys during their processing. In particular, the indentation measurements indicated that the strength of the martensite phase reduces by about 37% when quenched from 810 °C compared to being quenched from 750 °C, while the strength of the ferrite phase remains about the same. In addition, during the 10% thickness reduction and bake hardening steps, the strength of the martensite phase shows a small decrease due to tempering, while the strength of the ferrite increases by about 50% by static aging.