• International Journal of Automotive Technology
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• v.6 no.3
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• pp.259-268
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• 2005

In order to analyze the sheet drawability, the measurement of the plastic strain ratio was carried out for the 5182 aluminum alloy sheets in which were cold rolled without lubrication and subsequent recrystallization annealing. The average plastic strain ratio of the 5182 aluminum sheets was 1.50. It was considered that the higher plastic strain ratio was resulted from the ND//<111> component evolved during rolling and maintained during annealing. The AA5182/polypropylene/AA5182 (AA/PP/AA) sandwich sheets of the 5182 aluminum alloy skin sheet and the polypropylene core sheet with high formability have been developed for application for automotive body panels in future light weight vehicles with significant weight reduction. The AA/PP/AA sandwich sheets were fabricated by the adhesion of the core sheet and the upper and lower skin sheets. The AA/PP/AA sandwich sheet had high plastic strain ratio (1.58), however, the planar anisotropy of the sandwich sheet was little changed after fabrication. The optimum combination of directionality of the upper and lower skin sheets having high plastic strain ratio and low planar anisotropy was calculated theoretically and an advanced process for producing the sandwich sheets with high plastic strain ratio was proposed. The developed sandwich sheets have a high average plastic strain ratio of 1.55 and a low planar anisotropy of 0.17, which was improved more by 3.2 times than that of 5182 aluminum single sheet.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.454-461
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• 2011

In this study, the relationship between corrosion resistance and microstructural characteristics such as grain size reduction, preferred orientation, and homogenous distribution of elements and impurity by mechanical milling of magnesium powder was investigated. Mechanical milling of pure magnesium powder exhibited a complex path to grain refinement and growth together with preferred orientation reversal with milling time. It was also found that anisotropic formation of dislocation on the basal plane of magnesium was initially the dominant mechanism for grain size reduction. After 60 hrs of milling, grain coarsening was observed and interpreted as a result of the strain relaxation process through recrystallization. In spite of the finer grain size and strong (002) texture developed in the sample prepared by spark plasma sintering at $500^{\circ}C$ for 5 min after mechanical milling for 2hrs, the sample showed a higher corrosion rate. The results from this study will be helpful for better understanding of the controlling factor for corrosion resistance and behaviors of mechanical milled magnesium powders.

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.72-79
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• 2022

A cold roll-bonding process using AA1050, AA5052 and AA6061 alloy sheets is performed without lubrication. The roll-bonded specimen is a multi-layer complex aluminum alloy sheet in which the AA1050, AA5052 and AA6061 sheets are alternately stacked. The microstructural evolution with the increase of annealing temperature for the roll-bonded aluminum sheet is investigated in detail. The roll-bonded aluminum sheet shows a typical deformation structure in which the grains are elongated in the rolling direction over all regions. However, microstructural evolution of the annealed specimen is different depending on the type of material, resulting in a heterogeneous microstructure in the thickness direction of the layered aluminum sheet. Complete recrystallization occurs at 250 ℃ in the AA5052 region, which is lower by 100K than that of the AA1050 region. Variation of the misorientation angle distribution and texture development with increase of annealing temperature also differ depending on the type of material. Differences of microstructural evolution between aluminum alloys with increase of annealing temperature can be mainly explained in terms of amounts of impurities and initial grain size.

• Korean Journal of Materials Research
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• v.3 no.1
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• pp.43-49
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• 1993

Excellent deep drawability and strain aging rsistance are obtained by the addition of alloying elements such as Ti and Nb which can form carbide and nitride easily into Al killed extra low carbon steel. Recrystallization textures and mechanical properties of the three different extra low carbon steels with B containing Nb only, Ti only, and both Nb and Ti, respectively, along with have been compared. Inverse pole figure shows that (100) and (111) texture intensities of Nb containing steel changed a lot during the annealing treatment and the degree of texture-structural change in the steel containing both Nb and Ti is about the same as that in the Ti-containing 5teel. After annealing the pole figure shows that the {Ill} < 110 > and {112} < 110> textures are the strongest in the cold rolled state and the annealed state, respectively. However, there is little difference in texture structure among the three kinds of steels. There is a tendency that the steel containing both Nb and Ti the grain size of which is the smallest is the highest in hardness. Nb-containing steel is the next and Ti -containing steel is the last in hardness.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.131-139
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• 1993

Abstract Alloying elements such as AI, Ti, Nb and B in the extra low carbon AI-killed steel precipitate as nitrides or carbides and change the recrystallization texture structure of the steel during heattreatment with the result of strong effects on the deep drawability of the steel sheet. In this study the effects of fine precipitates such as nitrides and carbides on the texture of extra low carbon steels into which Ti, Nb, B, P, Si and Mn were added as alloying elements were investigated by means of TEM, SEM and optical microscopic analyses. Fine N$b_2$C and T$i_2$AIN precipitates are mainly observed in the steel containing both Nb and Ti, while fine AIN and coarse BN precipitates are observed in the Nb~containing steel and coarse T${i_4}{N_3}$ and ${N_10}{N_22}$/T$i_68$ precipitates are observed in the Ti-containing steel. The grain size of the Ti containing steel is larger than that of the Nb containing steel and that of the one containing both Nb and Ti.

• The Journal of the Petrological Society of Korea
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• v.19 no.3
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• pp.227-244
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• 2010

Abundant spinel lherzolite xenoliths showing distinctively different textural types such as protogranular, porphyroclastic, and mylonitic texture are trapped in the basaltic rocks from southeastern part of Jeju Island. These xenoliths show the textural spectrum from coarse-grained protogranular through porphyroclastic with bimodal grain size to fine-grained and foliated mylonitic texture. They tend to decrease in grain sizes and show more linear grain boundaries and more frequent triple junctions from protogranular through porphyroclastic to mylonitic. Spinel has different occurrence mode according the textural type. Spinel is always associated with orthopyroxene in protogranular texture, whereas it is scattered and independent of orthopyroxene in mylonitic texture. Additionally, porphyroblast from porphyroclastic and mylonitic textures has internal deformation features such as kink band, undulatory extinction and curved lamella, whereas neoblast is strain-free. These textural features indicate increasing degree of static/dynamic recrystallization from protogranular through porphyroclastic to mylonitic texture. The mg#[$=100{\times}Mg/(Mg+Fe_t)$] of olivine, orthopyroxene and clinopyroxene is relatively constant (ol: 88-91; opx: 89-92; cpx: 89-92) regardless of textural differences. The mg# of constituent minerals, NiO content (0.3~0.4 wt%) and MnO content (0.1~0.2 wt%) of olivine are similar to those of mantle xenoliths worldwide, also indicating that studied spinel lherzolite xenoliths were mantle residues having experienced 20~25% partial melting. The geochemical and textural characteristics have close relations showing that LREE and incompatible trace elements content of orthopyroxene and clinopyroxene increases from protogranular through porphyroclastic to mylonitic. These observations suggest that the studied mantle xenoliths experienced metasomatism by LREE enriched melt or fluid after partial melting, indicating a close relation between deformation and metasomatism. The metasomatism was possibly confined to narrow shear zones from where porphyroclastic and mylonitic textured xenoliths originated. These shear zones might favorably drive the percolation of LREE-enriched melts/fluids responsible for the metasomatism in the lithospheric mantle below the Jeju Island.

• Journal of the Mineralogical Society of Korea
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• v.19 no.3 s.49
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• pp.139-151
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• 2006

Base metal sulfides occur in the Huronian sedimentary rocks that cover the Archean volcanic rocks in the Cobalt area, Ontario, Canada. They are mostly concentrated in the basal conglomerate which was formed in the pre-Huronian basin structure. Sulfide occurrence can be grouped as massive sulfide clasts in the basal and Coleman conglomerate, disseminated sulfides throughout the sediments, and disseminated sulfides near Ag-Co-Ni-As carbonate veins. Detrital mechanism can explain features such as angularity of sulfide fragments and graded bedding of dissemnated sulfides. Sulfides concentrated near carbonate veins are probably of hydrothermal origin. Nearby strata-bound type massive sulfide ore deposits and mineralized interflow units are the most probable sources for syngenetic sulfides. This is supported by the angularity of sulfide fragments, presence of massive sulfide boulders which are identical in mineralogy and texture to the strata-bound type sulfide deposits in the Archean basement, and a similar composition of sphalerite in the Archean volcanic rocks and Huronian sedimentary rocks. Some sulfide grains, especially in sandstones and argillites, were undergone recrystallization during the intrusion of the Nipissing diabase.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.357-363
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• 1994

The irradiation growth of the Zircaloy-4 cladding in the KOFA fuel loaded in the Kori-2 nuclear plant was measured to evaluate the irradiation growth behavior and to be compared with that of the Siemens cladding having different manufacturing process. Due to the partial recrystallization by final heat treatment, the KOFA Zircaloy-4 cladding showed a two step irradiation growth behavior such as the growth saturation and the accerlation which is typical of the fully annealed Zircaloy cladding. The difference in the measured irradiation growth rate between the KOFA and the Siemens cladding could be explained by the difference in the cladding texture which depends on the manufacturing process. From the measured irradiation growth data of Kori-2 KOFA fuel, a two-step irradiation growth model of the KOFA Zircaloy-4 cladding was derived, the accuracy of which can be more clearly verified as the measured data of the irradiation growth are accumulated in the future.

• Economic and Environmental Geology
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• v.51 no.4
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• pp.323-343
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• 2018

This study defines the mineralogical, micro-textural and geochemical characteristics for the carbonate rocks and discusses the fluids that have affected the depositional environment of the Lower Makgol Formation in Seokgaejae section. Based on analysis of X-ray Diffraction (XRD), Scanning Electron Microscope-Energy Dispersive X-ray Spectrometry (SEM-EDS), Electron Probe Micro Analyzer-Wavelength Dispersive X-ray Spectrometry (EPMA-WDS) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS), carbonate miorofacies in the basal and the lower members of the Makgol Formation are distinguished and classified into four types. Type 1 dolomite (xenotopic interlocking texture) and Type 2 dolomite (idiotopic interlocking texture) have relatively high Mg/Ca ratio, flat REE pattern, low Fe and Mn. Extensively interlocking textures in these dolomites indicate constant supply of Mg ion from hypersaline brine. Type 3 and Type 4 dolomite (scattered and loosely-aggregated texture) have relatively moderate Mg/Ca ratio, MREE enriched pattern, low to high Fe and Mn. These partial dolomitization indicate limited supply of Mg ion under the influx of meteoric water with seawater. Also, the evidence of Fe-bearing minerals, recrystallization and relatively high Fe and Mn in Type 4 indicates the influence of secondary diagenetic fluids under suboxic conditions. Integrating geochemical data with mineralogical and micro-textural evidence, the discrepancy between the basal and the lower members of the Makgol Formation indicates different sedimentary environment. It suggest that hypersaline brine have an influence on the basal member, while mixing meteoric water with seawater have an effect on the lower member of the Makgol Formation.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.427-437
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• 2020

Manganese nodules, which are evaluated as potential metal resources, have been found in the Arctic Ocean as well as in the abyssal plains of the Pacific and Indian Oceans. Manganese nodules exhibit strong variations in the morphology, internal texture, chemical composition and mineralogy as they grow. The relationship between the texture and chemical elemental composition during the growth process is well documented, but the mineral composition variation during the growth process is not. Because the manganese oxide minerals in nodules are fine-grained and poorly crystalline, quantitative analysis for the mineral composition is challenging for the bulk nodule sample. This study investigated the internal texture and Mn-oxide mineral composition of manganese nodules obtained from the East Siberian Sea. Semi-quantitative analysis was attempted for three main Mn-oxide minerals constituting the manganese nodules (i.e., todorokite, buserite and birnessite) using the peak area ratio of X-ray diffraction analysis graphs. In the East Siberian Sea manganese nodules, birnessite is more abundant than buserite or todorokite, and no correlation is found between the mineral composition and the internal texture. Instead a correlation is found between the relative content of todorokite and the lamellae depth. The todorokite content tends to increase from the surface to the core of the nodules, which can be attributed to a recrystallization process or difference in the growth rate within the nodule. This study shows that semi-quantitative analysis of manganese oxide minerals using the peak area ratio is useful in the mineralogical study of manganese nodules.