Hyoung Seop Kim

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The mechanical stability of austenite in steels which rely on transformation–induced plasticity is usually attributed to its chemical composition, size and shape. We demonstrate here that another factor, the partitioning of strain between phases with different mechanical properties, can dramatically influence the stability. Many modern steels rely on a(More)
TWIP-cored three-layer steel sheets were newly fabricated by hot rolling of TWIP steel sheet surrounded by low-carbon (LC) or interstitial-free (IF) steel sheets. TWIP/LC or TWIP/IF interfaces were well bonded without pores or voids, while a few pearlites were thinly formed along the interfaces. The strengths and elongation of the TWIP-cored sheets(More)
In order to broaden industrial applications of Mg alloys, as lightest-weight metal alloys in practical uses, many efforts have been dedicated to manufacture various clad sheets which can complement inherent shortcomings of Mg alloys. Here, we present a new fabrication method of Mg/Al clad sheets by bonding thin Al alloy sheet on to Mg alloy melt during(More)
The concept of multiscale architectured materials is established using composition and grain size gradients. Composition-gradient nanostructured materials are produced from coarse grained interstitial free steels via carburization and high-pressure torsion. Quantitative analyses of the dislocation density using X-ray diffraction and microstructural studies(More)
In general, melting process is not a common method for the production of oxide dispersion strengthened (ODS) alloys due to agglomeration and coarsening of oxide particles. However, vacuum casting process has recently been employed as a promising process to produce micro-scale oxide dispersed alloys. In this paper, we report the process and characterization(More)
We report the mechanistic explanation of the variation in Lüders strain in fine-grained transformation-induced plasticity assisted steel. The austenite stability is demonstrated to have a profound influence on the Lüders strain. Furthermore, it is shown unambiguously using a thermodynamic analysis that the transformation of austenite is strain-induced. The(More)
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