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Renlong Xiong,Yi Liu,Haitao Si,Huabei Peng,Shanling Wang,Binhan Sun,Hanxin Chen,Hyoung Seop Kim,Yuhua Wen 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
In order to improve the work hardening capacity under low stresses and the yield strength of conventional Hadfield steels, theeffects of Si on the microstructure and work hardening behavior of the Fe‒17Mn‒1.1C‒xSi steels under both quasi-statictensile and low load impact are investigated. It is shown that the increase of the Si contents remarkably improves the yieldstrength by 36 MPa per 1 wt% Si in the investigated steel system without significant sacrifice of ductility. The decreasingeffect of Si on the stacking fault energy is strongly affected by carbon, although the variation of carbon content was small. This led to the unexpected similar stacking fault energy between 1Si and 2Si steel. With the increase of the Si contents forthe steels, the critical strain for the onset of mechanical twinning was lowered, which was controlled by the cooperationbetween the stacking fault energy and solid solution strengthening of Si. This resulted in the earlier initiation of mechanicaltwins and an increase in the twin volume fraction. Therefore, the work hardening capacities under both quasi-static tensileand low load impact tests were enhanced. It was also found that the impact deformation decreased as more mechanical twinsabsorbed the impact energy.
Yi Liu,Yiming Yu,Tuanwei Zhang,Renlong Xiong,Hyoung Seop Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.4
A new image-processing method based on block-gradient segmentation was proposed to measure the volume fraction ofmechanical twins in metallographic images. The processing results showed that this automatic method could be used forrapid and effective measure of the twin-volume fractions of twinning-induced plasticity steels in metallographic images underdifferent strain conditions. The entire processing time for each image is relatively short, which would benefit researchersprocessing a large number of metallographic images. This method may pave a way to develop a simple, effective plug-in tomeasure rapidly the twin-volume fractions in the software for metallographic observations, and it would be beneficial forpreliminary analysis of microstructural evolutions and subsequent characterization of mechanical twins by high-resolutionmicroscopy using electron microscopy.
Wenke Wang,Jaimyun Jung,Chao Cui,Wenzhen Chen,Yang Yu,Peng Li,Wencong Zhang,Renlong Xiong,김형섭 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4
In this work, the anisotropy variation of tensile flow stress for AZ31 magnesium alloys was investigated at various temperaturesand tensile strains with the help of the visco-plastic self-consistent model. The results showed that the anisotropyof flow stress was weakened with the increase of tensile temperature, while such anisotropy presented a slightly increasingstage first and then a continuously decreasing stage with the increase of tensile strain. During the tension deformation, theactivations of basal slip and tension twinning, together contributed to the development of a (0002)//LD (LD: loading direction)type texture. In contrast, the activations of prismatic slip produced a ⟨10–10⟩//LD type texture. Such texture variationsinfluenced the Taylor factors, but did not cause significant differences in the flow stress. By comparison, the difference inthe macroscopic average resolved shear stress, which was calculated according to the critical resolved shear stress of eachdeformation mode and their respective activation fractions, decreased significantly with the increase of tensile temperatureor tensile strain. This was the major reason for the decline of the tension deformation behavior anisotropy.