• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 1999.05a
• /
• pp.81-81
• /
• 1999

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1996.05a
• /
• pp.94-95
• /
• 1996

• 한국전기화학회:학술대회논문집
• /
• 2001.10a
• /
• pp.21-21
• /
• 2001

• Journal of Welding and Joining
• /
• v.31 no.5
• /
• pp.47-53
• /
• 2013

We have investigated the traits of clad metals in hot-rolled clad steel plates, including the sensitization and mechanical properties of STS 316 steel plate and carbon steel (A516), under various specific circumstances regarding post heat treatment, multilayered welds, and thick or repeated welds for repair. For evaluations, sectioned weldments and external surfaces were investigated to reveal the degree of sensitization by micro vickers hardness, tensile, and etching tests the results were compared with those of EPR tests. The clad steel plates were butt-welded using FCAW and SAW with the time of heat treatment as the variable, a that was conducted at $625^{\circ}C$, for 80, 160, 320, 640, and 1280 min. Then, the change in corrosion resistance was evaluated in these specimens. With carbon steel (A516), as the heat treatment time increased, the annealing effect caused the tensile strength to decrease. The micro-hardness gradually increased and decreased after 640 min. The elongation and contraction of the area also increased gradually. The oxalic acid etch test and EPR test on STS316 and the clad metal showed STEP structure and no sensitization. From the test results on multi-layered and repair welds, it could be concluded that there is no effect on the corrosion resistance of clad metals. The purpose of this study was to suggest some considerations for developing on-site techniques to evaluate the sensitization of stainless steels.

• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.4
• /
• pp.476-489
• /
• 1999

This paper is concerned with the deployment of core technologies for automotive steel sheets, based on the structural change of global market. The main tasks of automotive industry are to ensure the energy consumption, environmental regulations, and driving safety. With social and legal requirements, this study analyzes the market creation processes with technological innovations for hot rolled, cold rolled and galvanized steel sheets during the 20th century. It has been proven that the leading country in the steel industry was also that in the automotive. The purchaser-supplier relations of sheet materials are then patternized in the regional markets of the United States and Japan, who share nearly 50% of market in the world. According to the paradigm shift of globalization, the balance of power in Porter's 5 forces has been moved to the buyers', and both industries pursue Win-Win strategies such as the PNGV(Partnership for a New Generation of Vehicles ) and design-in system with the competition.

• Transactions of Materials Processing
• /
• v.7 no.2
• /
• pp.150-157
• /
• 1998

Recently the SPPC technology is being developed in steel rolling industries for the purpose of enhancing mechanical properties of rolled sheets. The technology is to produce steel sheets with finer and more uniformly distributed grains by prediction of recrystallization behaviors and on-line control of rolling parameters during hot rolling process. In this study a finish rolling process was analyzed by a three-dimensional rigid-thermoviscoplastic finite element method and recrystallization behaviors of several locations in the sheet were predicted by Sellars equations. As a result it was found that the initial grain size of 84 ${\mu}m$ became $21-23\;{\mu}m\;20-22{\mu}m\;and\;18-20{\mu}m$ at front middle and end portions of the sheet respectively. It was also found that variations of the grain size became $$0.6{\sim}2{\mu}m\;and\;10{\mu}\mum$$ in thickness and width directions respectively.

• Transactions of Materials Processing
• /
• v.9 no.1
• /
• pp.66-71
• /
• 2000

The present study tackles the metallurgical subjects involving the thin slab-direct hot rolling process, i.e. mini-mill process. In order to clarify the effect of chemical composition of steel and MnS precipitation behaviors on the development of edge cracking during hot rolling, the content of manganese and sulfur in low carbon steel was varied and the isothermal treatment prior to roughing was applied. Edge cracking during roughing in the hot-rolling process of mini-mill was effectively prevented by means of the isothermal treatment at 115$0^{\circ}C$ for 5 minutes in the 0.4% manganese steel containing sulfur lower than 0.013%. With the increase in manganese content in low carbon steel, coarser MnS developed. The edge cracking index which denotes the total length of edge crack per unit edge-length of rolled specimens was proposed in this paper. It was found that the edge cracking index linearly decreased with the increase in the ratio of MnS.

• Steel and Composite Structures
• /
• v.12 no.1
• /
• pp.31-51
• /
• 2012

Local buckling can be ignored for hot-rolled ordinary strength steel equal angle compression members, because the width-to-thickness ratios of the leg don't exceed the limit value. With the development of steel structures, Q420 high strength steel angles with the nominal yield strength of 420 MPa have begun to be widely used in China. Because of the high strength, the limit value of the width-to-thickness ratio becomes smaller than that of ordinary steel strength, which causes that the width-to-thickness ratios of some hot-rolled steel angle sections exceed the limit value. Consequently, local buckling must be considered for 420 MPa steel equal angles under axial compression. The existing research on the local buckling of high strength steel members under axial compression is briefly summarized, and it shows that there is lack of study on the local buckling of high strength steel equal angles under axial compression. Aiming at the local buckling of high strength steel angles, this paper conducts an axial compression experiment of 420MPa high strength steel equal angles, including 15 stub columns. The test results are compared with the corresponding design methods in ANSI/AISC 360-05 and Eurocode 3. Then a finite element model is developed to analyze the local buckling behavior of high strength steel equal angles under axial compression, and validated by the test results. Following the validation, a finite element parametric study is conducted to study the influences of a range of parameters, and the analysis results are compared with the design strengths by ANSI/AISC 360-05 and Eurocode 3.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.5 s.78
• /
• pp.637-648
• /
• 2005

Innovative prestressed steel plate girders were presented in this study. Hot-rolled H beams were loaded first, then relatively high-strengthsteel plates were welded on the top and bottom flanges of preloaded H beams. Finally, high prestressed plate (HiPP) girder was manufactured by simply releasing prestresses of rolled beams. To verify prestress distributions induced in this girder, the experimental study was conducted and some guidelines to manufacture these girders effectively were addressed. In addition, methods to determine the allowable bending stress of HiPP girders and to check welding stresses were addressed for design of temporary bridges. The efficiency and effectiveness of the present girder were demonstrated through design examples of temporary bridges adapting the prestress-induced girder or the plate girder of the same section without prestresses. As a result, it has been found to be possible that the span length of HiPP girders for temporary bridges is longer than that of girders without prestresses.

• Journal of the Korean Magnetics Society
• /
• v.11 no.1
• /
• pp.1-7
• /
• 2001

We investigated to DC magnetic characteristics, the dependence of annealing temperature on the crystal grain and the crystalline orientation for grain-oriented silicon ribbon with 100 $\mu\textrm{m}$ final thickness manufactured by three times cold rolling method using the hot-rolled silicon steel plate as a raw material. The growth of (110)[001] Goss texture were almost observed in the whole area of the sample. The values of the saturation magnetic flux density B$\sub$s/ and the average ${\alpha}$ angle have 1.9 T and 4.6 degrees respectively. From this result we could be confirmed that the three times cold rolling method has a possibility of manufacture for oriented ultra-thin silicon ribbons much more simple and cheeper than the existing oriented silicon steel manufacturing method by means of more simplified producing process.