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김동건,이기정,이준정 대한금속재료학회(대한금속학회) 1984 대한금속·재료학회지 Vol.22 No.10
Effect of transformed ferrite content on the mechanical properies of dual-phase steels has been studied and analyzed on the basis of observation on the austenite-to-ferrite transformation behavior during post-anneal cooling. Various contents of transformed ferrite were obtained by changing intercritical annealing temperature. As the transformed ferrite content was increased up to about 40%, dual-phase properties became better due to the finer distribution of martensite particles. However, the dual-phase properties were deteriorated when the transformed ferrite content becomes larger than the retained ferrite content. The significance of these results is discussed in relation to the austinite-to-ferrite trans formation behavior during intercritical annealing.
金東健 전북대학교 공업기술연구소 1980 工學硏究 Vol.10 No.-
Zinc-ferrite is an undesirable compound in the hydrometallurgy of zinc. However, it is unavoidably formed during the roasting process of the marmatite ore. Zinc-ferrite is insoluble in the dilute sulfuric acid solution and is remained in the residue after leaching process that the considerable amount of zinc is lost. In this experiment, the formation of synthetic Zinc-ferrite is studied by use of the chemically pure ZnO and Fe_2O_3. The results obtained are as follows; 1. the amount of the formation of zinc-ferrite is prorortional to the heating temperature. 2. the closer the particles are, the more the amount of zinc-ferrite should be. As a result, it would be desirable to use the fluo-solid roaster than the multiple hearth roaster as roasting apparatus.
金東健,朴永九,陳載寬 전북대학교 공업기술연구소 1984 工學硏究 Vol.15 No.-
Dual phase steel are known to have hard martensite dispersed in soft ferrite matrix. Dual phase steels have high accelerated aging properties and, so was focused on it. The strength of both air cooled and water quenched dual phase steels was increased through aging for 20~30 min at about 170℃. The above time and temperature are conventional paint oven conditions and this aging is ofter referred to as "bake-hardening". Heat treatment for dual phase steel fabrication was done at several different temperatures before aging. To make good dual phase steels they were heated at 760℃. Aging was conducted at temperatures from 150℃ to 250℃ for quenched and forced air cooled specimens. Strain aging was conducted for specimens pre-strained 0% to 10% by uniaxial tension. The results obtained in this experiment were as follows : 1. Mechanical properties of water quenched and aged specimens were better than those of forced air cooled and aged specimens. 2. Yield strength was increased by about 10kg/㎟ through quenching age and about 25kg/㎟ through strain aging in this experiment. 3. The activation energy for aging was estimated as 25,000 cal/mole.