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Unami S.,Jfe Holdings | Ozaki Y.,Steel Res Laboratory
JFE Technical Report

The fatigue strength of the sintered and carburized compact made of the Mo hybrid-alloyed steel powder, which is based on a 0.6 mass% Mo prealloyed steel powder to which 0.2 mass% Mo powder particles have been diffusion bonded, is higher than that of the 0.6 mass% Mo prealloyed steel powder. The sintered compact made of the Mo hybrid-alloyed steel powder has a finer pore structure than that of the Mo prealloyed steel powder, because the Mo-rich region near the surface of the Mo hybrid-alloyed steel powder should exist as the a-iron phase with a high diffusion coefficient at high temperature and result in enhanced sintering. Improvement in the fatigue strength of the sintered and carburized compact made of the Mo hybrid-alloyed steel powder should result from not only the fine pore structure but also the strengthening of the sintering neck by Mo concentration around pores. Copyright © 2007 JFE Steel Corporation. Source

Shotani K.,Steel Res Laboratory | Nakamura M.,Japan Steel Works
JFE Technical Report

The corrosion resistant steel for ballast tank "JFE-SIP™-BT", which prolongs coating life by preventing coating deterioration, has been developed. The developed steel has been applied to ballast tanks of a very large ore carrier (VLOC). This paper reports evaluation results on coating deterioration and corrosion behavior of the developed steel after 5-year use. The parts applied were upper deck plates and longitudinal members of upper deck of ballast tanks. Doubling plates were welded to upper deck plates of ballast tanks and were coated simultaneously with the upper deck plates. The coating deteriorated area, corrosion depth and corrosion volume of the developed steel were 75%, 84%, and 58% of those of the conventional steel, respectively. The deteriorated length at the edge of longitudinal members in the developed steel was about 65% of that in the conventional steel. The prevention effect of coating deterioration by the developed steel was confirmed under the actual ballast tank condition. Copyright © 2015 JFE Steel Corporation. All Rights Reserved. Source

Nishina Y.,Steel Res Laboratory | Imanishi D.,Steel Res Laboratory | Shibuya K.,Analysys
JFE Technical Report

Effective diagnostic technology of defects such as steel structures and machine parts has been developed by detecting a minute temperature change using highly precise infrared thermography, including the application of a thermoelasticity heat generation method to crack diagnosis and stress measurement. Also JFE Steel Group applied a supersonic wave excitation method to the crack diagnosis and we achieved various effective deterioration diagnoses in iron and steel manufacturing facilities. Some selected technologies have been currently applied to measurement business of JFE Steel Group. Source

Ueki T.,Steel Res Laboratory | Shiozaki Y.,Steel Res Laboratory | Kamura H.,Steel Res Laboratory
JFE Technical Report

An investigation against the occurrence of a large-scale earthquake predicted to occur in the near future has been carried out in JFE Steel to protect human life, avoid a major disaster to communities in the area and maintain operations. It is important to predict the type of seismic wave the authors encounter in order to prepare reasonable plans for seismic retrofitting of structures and plants. This paper discusses the method estimating the latest strong ground motion using a site amplification factor reflecting local strata inspected by the original boring data and the seismic observation. This method to predict earthquake damages contributes to an effective investment. Source

Nakagawa K.,Steel Res Laboratory | Ueki T.,Steel Res Laboratory | Nanba T.,Steel Res Laboratory
JFE Technical Report

Since the initial approval for "HBLTM385," 550 N/mm2 class steel plate for building structure by the Minister of Land, Infrastructure, Transport and Tourism in 2002, JFE Steel has developed 550 N/mm2 class building materials and products, such as circular steel tube and cold-press-formed square steel tube, as a pioneer in the industry. This paper explains the outline of "HBLTM385 series" including its excellent mechanical properties as a building material and economic advantadge, and provides some fi ndings about its structural design and fi re-resistant design. Source

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