【新文速递】2024年5月23日固体力学SCI期刊最新文章

 

今日更新：Mechanics of Materials 1 篇，International Journal of Plasticity 2 篇

Mechanics of Materials

Temperature effects on the lifetime reinforcement due to strain-induced crystallization in carbon black filled natural rubber under non-relaxing torsion: Comparison with non-relaxing tensile loadings

Yasser Mouslih, Jean-Benoît Le Cam, Benoît Ruellan, Isabelle Jeanneau, Frédéric Canevet

doi:10.1016/j.mechmat.2024.105045

温度对非松弛扭转下炭黑填充天然橡胶中应变诱导结晶寿命增强的影响:与非松弛拉伸载荷的比较

This paper investigates the lifetime reinforcement at different temperatures of carbon black filled natural rubber under non-relaxing torsion. Torsion fatigue tests with different angle ratios have been carried out with axisymmetric-shaped specimens. Finite element analysis was used to predict the local mechanical state by taking into account temperature effects and stress softening heterogeneities. It has been shown that when the temperature of the test is increased, mechanical response does no longer stabilize, contrary to what is observed when the test is carried out at ambient temperature. A strategy has been proposed to evaluate an equivalent loading ratio, in order to compute the minimum loading as the Cauchy stress normal to the crack plane for the minimum torsion angle applied and to represent the results in the Haigh diagram. It was found that the lifetime reinforcement under torsion loading decreases when the temperature is increased to 90 °C, but is still observed. The lifetime reinforcement under torsion at 90 °C was of the same amplitude as the one obtained with the same material under uniaxial tension at the same temperature. The study has been completed by post-mortem analysis at the macro- and the microscale in order to characterize damage mechanisms at 90 °C.

研究了炭黑填充天然橡胶在不同温度下的非松弛扭转寿命增强。采用轴对称形试样进行了不同角度比的扭转疲劳试验。考虑温度效应和应力软化非均质性，采用有限元方法预测局部力学状态。已经证明，当测试温度升高时，机械响应不再稳定，这与在环境温度下进行测试时所观察到的情况相反。提出了一种评估等效加载比的策略，以便计算最小扭转角下裂缝面法向柯西应力的最小加载，并在Haigh图中表示结果。结果表明，当温度升高到90℃时，扭转载荷下的寿命增强有所降低，但仍有明显的增强。在90°C扭转下的寿命增强幅度与相同材料在相同温度下的单轴拉伸下获得的寿命增强幅度相同。为了表征90°C下的损伤机制，该研究已通过宏观和微观尺度的死后分析完成。

International Journal of Plasticity

New insights into annealing induced hardening and deformation mechanisms in a selective laser melting austenitic stainless steel 316L

Zhiping Zhou, Jinlong Lv, Maolei Gui, Weiqi Yang

doi:10.1016/j.ijplas.2024.104008

选择性激光熔化316L奥氏体不锈钢退火诱导硬化和变形机制的新认识

Annealing softening is commonly observed in traditional coarse–grained materials. Herein, an annealing–induced hardening mechanism in selective laser melted 316L stainless steel (SLM–ed 316L SS) was investigated. The SLM–ed 316L SS, without prior cold–working history, displayed evident hardening behaviour as the annealing temperature increased from 400°C to 500°C. Several dedicated scanning transmission electron microscope and quasi–in–situ/electron backscatter diffraction techniques were employed to investigate the intrinsic characteristics evolution of the samples, including cellular/wall dislocation structure, nano–particles/segregation, dislocation density, crystallographic orientations, and low–angle grain boundaries (LAGBs).This phenomenon primarily arises from unique guardrail–like dislocation walls decorated with nano–particles (O, Cr, Mo, and Si) and a high proportion of LAGBs, hindering movement of dislocations and leading to their accumulation. Furthermore, this structure and the stable configuration of columnar crystals can synergistically affect the 500°C annealed sample, resulting in a high yield stress of 628 MPa. On the other hand, complex deformation substructures, such as stacking faults, Lomer–Cottrell locks, and forest dislocations, also proliferated during deformation. These substructures enabled multiscale plastic strain partitioning, intensifying strain hardening and realizing a strength–ductility combination of a comparable yield/ultimate tensile strength of 628 MPa/789 MPa and tensile ductility of 32%. Dislocation motion was the dominant deformation mechanism based on the strengthening mechanism model in this study.

退火软化是传统粗粒材料中常见的现象。研究了选择性激光熔化316L不锈钢(SLM-ed 316L SS)的退火诱导硬化机制。在没有冷加工历史的情况下，当退火温度从400°C升高到500°C时，SLM-ed 316L SS表现出明显的硬化行为。采用专用扫描透射电子显微镜和准原位/电子背散射衍射技术研究了样品的内在特征演变，包括胞/壁位错结构、纳米颗粒/偏析、位错密度、晶体取向和低角晶界(LAGBs)。这种现象主要是由于独特的护栏状位错壁由纳米颗粒(O、Cr、Mo和Si)和高比例的LAGBs装饰而成，阻碍了位错的移动并导致其积累。此外，这种结构和柱状晶体的稳定构型可以协同影响500°C退火样品，导致628 MPa的高屈服应力。另一方面，复杂的变形子结构，如层错、lomo - cottrell锁和森林位错，也在变形过程中增殖。这些子结构实现了多尺度塑性应变分配，强化了应变硬化，实现了屈服/极限抗拉强度为628 MPa/789 MPa，抗拉延性为32%的强度-延性组合。基于本研究的强化机制模型，位错运动是主要的变形机制。

Dynamic precipitation and recrystallization behavior during hot deformation of Al-Zn-Mg-Cu alloy: Experiment and modeling

Zinan Cheng, Cunsheng Zhang, Guannan Chu, Zhenyu Liu, Kuizhao Wang, Zijie Meng, Liang Chen, Lei Sun, Guoqun Zhao

doi:10.1016/j.ijplas.2024.103995

Al-Zn-Mg-Cu合金热变形过程中的动态析出与再结晶行为:实验与模拟

Featured with various excellent mechanical properties, the high strength Al-Zn-Mg-Cu alloys (7xxx series) have become one of the most widely-used metal materials. During the hot processing of 7xxx alloys, the high stacking fault energy and alloying element concentration can lead to the simultaneous occurrence of several physical mechanisms including the dynamic recovery (DRV), dynamic recrystallization (DRX), dynamic precipitation (DPN), and their interactions. Such complex microstructural mechanisms are difficult to be characterized and modeled in both of the experimental and theoretical aspects. In present work, aiming at 7055 alloy subjected to uniaxial hot compression, the systematic experiment investigation is first conducted to reveal hot deformation behaviors. Based on experimental analysis, a unified crystal plastic (CP) model, incorporating the DRX and DPN, is proposed by combining the viscoplastic self-consistent (VPSC) framework. In the unified model, the DRX and DPN behaviors are described by a physical based continuous dynamic recrystallization (CDRX) model and the classical Kampmann-Wagner numerical (KWN) model, respectively, and the effect of DPN on CDRX is specially modeled. After identifying the model parameters, the unified model can reasonably capture the essential features of DPN, DRX, and mechanical response under different deformation temperatures. Therefore, this study offers an innovative modeling approach for the dynamic evolution of several physical processes, facilitating the further understanding for the hot deformation behaviors of aluminum alloys.

高强度Al-Zn-Mg-Cu合金(7xxx系列)具有各种优异的力学性能，已成为应用最广泛的金属材料之一。在7xxx合金热加工过程中，高的层错能和合金元素浓度可导致动态恢复(DRV)、动态再结晶(DRX)、动态析出(DPN)等多种物理机制同时发生，以及它们之间的相互作用。这种复杂的微观结构机制在实验和理论方面都难以表征和建模。本文首先针对7055合金单轴热压缩进行了系统的实验研究，揭示了其热变形行为。在实验分析的基础上，结合粘塑性自一致(VPSC)框架，提出了包含DRX和DPN的统一晶体塑性(CP)模型。在统一模型中，分别用基于物理的连续动态再结晶(CDRX)模型和经典的Kampmann-Wagner数值(KWN)模型来描述DRX和DPN的行为，并特别模拟了DPN对CDRX的影响。在确定模型参数后，统一模型可以合理地捕捉到不同变形温度下DPN、DRX和力学响应的基本特征。因此，本研究为几种物理过程的动态演变提供了一种创新的建模方法，有助于进一步了解铝合金的热变形行为。