Daegu, South Korea
Daegu, South Korea

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Lee S.E.,Korea Institute of Materials Science | Lee K.S.,Korea Institute of Materials Science | Kim M.J.,Korea Clad Technology Co. | Kwon Y.N.,Korea Institute of Materials Science
Journal of Korean Institute of Metals and Materials | Year: 2014

The influence of annealing treatment on the interface-correlated microstructural evolution and subsequent mechanical properties of an Al1050/AZ31B clad sheet was systematically investigated. A scanning electron microscope with an attached energy dispersive spectroscopy revealed that diffusive layer consisted of γ (Mg17Al12), and β (Mg2Al3) phases was generated and grown with increasing annealing time and temperature. Mechanical properties were evaluated by uniaxial tensile and peel tests. Improvement of bonding strength between A11050 and AZ31B by feasible annealing seemed to be strongly related to the generation of metallurgical bonding by a diffusive intermetallic compound layer whose overall thickness was limited to below 1.4 μm. Copyright © The Korean Institute of Metals and Materials.


Jeong E.-W.,Pusan National University | Hui K.N.,Pusan National University | Bae D.-H.,Korea Clad Technology Co. | Bae D.-S.,Dong - Eui University | Cho Y.-R.,Pusan National University
Metals and Materials International | Year: 2014

Aluminum clad steel (ACS) is an excellent layered composite material. An intensive investigation into roll-bonded ACS was carried out to identify the intermetallic compound (IMC) formed at the interface between the aluminum (Al) and the steel. A series of analyzing methods was applied to the IMC layer formed at the interface during annealing at 540°C for 16 h. An electron probe micro-analyzer (EPMA) measured a value of 28.5 atomic percent for the Fe in the IMC layer, which coincided with the Fe2Al5 phase. An analysis of the X-ray diffraction pattern for the IMC layer in the ACS materials showed a very strong peak for the (002) plane of Fe2Al5. Vickers microhardness testing of the IMC layer revealed a very high value (1,110 Hv). The results of EPMA, XRD and microhardness values verified that the IMC layer in the sample that had been annealed at 540°C for 16 h was the Fe 2Al5 phase. © 2014 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.


Kim D.,Korea Institute of Materials Science | Hwang B.K.,Korea Institute of Materials Science | Lee Y.S.,Korea Institute of Materials Science | Kim J.H.,Korea Institute of Materials Science | Kim M.-J.,Korea Clad Technology Co.
AIP Conference Proceedings | Year: 2010

The production of a stainless steel - clad aluminum sheet by the cold rolling process is a more efficient and economical approach compared with the other types of processes utilized for the production of such sheets. Because both the stainless steel and aluminum sheets show the highly anisotropic behavior, it is necessary to investigate anisotropic properties of clad sheets for the design of process. In this paper, to investigate the anisotropic properties of stainless steel - clad aluminum sheet, two kinds of clad sheets were considered: STS439/AA3003 and STS439/AA1050/STS304 clad sheets. The uni-axial tension tests at 0, 45 and 90 degrees for the rolling direction were performed to obtained yield stresses and R values. The strain ratio at balanced biaxial tension state was measured from compression disk test. In order to describe the anisotropic behavior of the clad sheet, nonquadratic anisotropic yield function Yld2000-2d was utilized. © 2010 American Institute of Physics.


Lee K.S.,Korea Institute of Materials Science | Lee S.E.,Korea Institute of Materials Science | Kim J.S.,Pohang University of Science and Technology | Kim M.J.,Korea Clad Technology Co. | And 2 more authors.
Journal of Korean Institute of Metals and Materials | Year: 2013

The aim of this article is to elucidate the influence of reduction ratio during roll bonding on the microstructural evolution, mechanical properties and room-temperature formability of Al-Cu 2-ply clad metal. The evolution of the interface microstructure was first characterized by a scanning electron microscope (SEM) and transmission electron microscope (TEM) attached with energy dispersive spectroscopy (EDS). The presence of an intermetallic compound as well as severe grain refinement was detected at the interface of the Al-Cu bimetal fabricated under the highest reduction ratio of 65% adopted in this study. Taking into account the difference of the microstructure with a reduction the ratio, mechanical properties and bonding strength were then evaluated by uniaxial tensile and peel tests. It was observed that the bonding strength, elongation and tensile strength for Al-Cu 2-ply sheets were incomparably reduced by decreasing the reduction ratio during the roll bonding process, which directly correlated with the microstructural evolution at the interface. Moreover, the higher reduction ratio during the roll bonding, the more room temperature formability could be achieved for Al-Cu 2-ply sheet by applying both three-point bending and Erichsen tests. © The Korean Institute of Metals and Materials.


Bae D.S.,Dong - Eui University | Chae Y.R.,Dong - Eui University | Lee S.P.,Dong - Eui University | Lee J.K.,Dong - Eui University | And 3 more authors.
Procedia Engineering | Year: 2011

Ti and Titanium/mild steel/titanium (Ti/MS/Ti) clad materials have been received much attention because of its high specific strength and corrosion-resisting properties compare to those of brass and stainless steels. But, it is difficult to make these materials because brittle intermetallic compound and titanium oxide form during heat treatment. The aim of this study is to get optimized cladding conditions. 1st grade Ti sheets and SPCC mild steel sheets were prepared and then Ti/MS/Ti clad materials were fabricated by cold rolling and post heat treatment process. Microstructure of Ti/MS interfaces was observed by using the SEM and EDX Analyser in order to investigate the effect of post heat treatment on bonding properties of Ti/MS/Ti clad materials. Diffusion bonding was observed at the interfaces of Ti/MS. The Knoop hardness of mild steel decreased with post heat treatment temperature, however, those of Ti decreased at the range of 500∼600 °C and showed uniform value till 800 °C and then increased rapidly up to 900 °C. The Knoop hardness value of diffusion layer showed higher one than those of Ti and mild steel matrices with post heat treated at 600 °C. Bonding forces of Ti/Mild steel interfaces were measured by the peel test and © 2011 Published by Elsevier Ltd.


Lee S.,Korea Institute of Industrial Technology | Kim S.-M.,Dong - Eui University | We S.-N.,Dong - Eui University | Bae D.-H.,Korea Clad Technology Co. | And 4 more authors.
Journal of Korean Institute of Metals and Materials | Year: 2012

The aim of this study is to investigate the effect of post heat treatment on bonding properties of roll cladded Ti/MS/Ti materials. First grade Ti sheets and SPCC mild steel sheets were prepared and then Ti/MS/Ti clad materials were fabricated by a cold rolling and post heat treatment process. Microstructure and point analysis of the Ti/MS interfaces were performed using the SEM and EDX Analyser. Diffusion bonding was observed at the interfaces of Ti/MS. The thickness of the diffusion layer increased with post heat treatment temperature and the diffusion layer was verified as having (ε+ζ+(ε+β-Ti) intermetallic compounds at 700°C and an (ε+β-Ti) intermetallic compound at 800°C, respectively. The micro Knoop hardness of mild steel decreased with post heat treatment temperature; however, those of Ti decreased at a range of 500~600 tl and showed a uniform value until 800°C. and then increased rapidly up to 900°C. The micro Knoop hardness value of the diffusion layer increased up to 700°C and then saturated with post heat treatment. A T-type peel test was used to estimate the bonding forces of Ti/Mild steel interfaces. The bonding forces decreased up to 800°C and then increased slightly with post heat treatment. The optimized temperature ranges for post heat treatment were 500~600°C to obtain the proper formability for an additional plastic deformation process.


Jeong E.-W.,Pusan National University | Kim H.-B.,Pusan National University | Kim D.-Y.,Pusan National University | Kim M.-J.,Korea Clad Technology Co. | Cho Y.-R.,Pusan National University
Korean Journal of Materials Research | Year: 2012

For heat exchanger applications, 2-ply clad materials were fabricated by rolling of aluminum (Al) and mild steel sheets. Effects of annealing temperature on interface properties, especially on inter-layer formation and softening of strain hardened mild-steel, for Al/mild steel clad materials, were investigated. To obtain optimum annealing conditions for the Al/mild steel clad materials, annealing temperature was varied from room temperature to 600°C. At the annealing temperature about 450°C, an inter-layer was formed in an island-shape at the interface of the Al/mild steel clad materials; this island expanded along the interface at higher temperature. By analyzing the X-ray diffraction (XRD) peaks and the energy dispersive X-ray spectroscopy (EDX) results, it was determined that the exact chemical stoichiometry for the inter-layer was that of Fe2Al5. In some samples, an X-layer was formed between the Al and the inter-layer of Fe2Al5 at high annealing temperature of around 550°C. The existence of an X-layer enhanced the growth of the inter-layer, which resulted in the delamination of the Al/mildsteel clad materials. Hardness tests were also performed to examine the influence of the annealing temperature on the cold deformability, which is a very important property for the deep drawing process of clad materials. The hardness value of mild steel gradually decreased with increasing annealing temperature. Especially, the value of hardness sharply decreased in the temperature range between 525°C and 550°C. From these results, we can conclude that the optimum annealing temperature is around 550°C under condition of there being no X-layer creation.

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