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Okawa T.,Nippon Steel & Sumitomo Metal Corporation | Shimanuki H.,Tube and Shape Research Laboratory | Nose T.,Welding and Joining Research Center | Suzuki T.,Materials Characterization Research Laboratory
Nippon Steel Technical Report | Year: 2013

A fatigue life prediction system for welded structures has been developed based on crack growth analysis. In the developed system, the fatigue life can be predicted taking into account the effects of the residual stress and the load sequences by the crack opening and closure simulation. Furthermore, the effect of fatigue strength improvement techniques, such as UIT, can be accurately predicted by the developed system. Source


Nishioka K.,Nippon Steel & Sumitomo Metal Corporation | Nishioka K.,Tokyo University of Science | Ichikawa K.,Tube and Shape Research Laboratory
Science and Technology of Advanced Materials | Year: 2012

The water-cooled thermomechanical control process (TMCP) is a technology for improving the strength and toughness of water-cooled steel plates, while allowing control of the microstructure, phase transformation and rolling. This review describes metallurgical aspects of the microalloying of steel, such as niobium addition, and discusses advantages of TMCP, for example, in terms of weldability, which is reduced upon alloying. Other covered topics include the development of equipment, distortions in steel plates, peripheral technologies such as steel making and casting, and theoretical modeling, as well as the history of property control in steel plate production and some early TMCP technologies. We provide some of the latest examples of applications of TMCP steel in various industries such as shipbuilding, offshore structures, building construction, bridges, pipelines, penstocks and cryogenic tanks. This review also introduces high heat-affected-zone toughness technologies, wherein the microstructure of steel is improved by the addition of fine particles of magnesium-containing sulfides and magnesium- or calcium-containing oxides. We demonstrate that thanks to ongoing developments TMCP has the potential to meet the ever-increasing demands of steel plates. © 2012 National Institute for Materials Science. Source


Kaneko M.,Tube and Shape Research Laboratory
Nippon Steel Technical Report | Year: 2012

The main field of application for weathering steel is bridges, since these are public structures which are required to have a service life of at least 100 years. For such long-life structures, minimizing the life cycle cost (LCC) is extremely important. Nippon Steel contributes much to minimization of LCC in the field of bridges through development of the key technology indispensable for bridge engineering, such as techniques to estimate the life of weathering steel, evaluate stable rust quantitatively and repair bridges. Through its research employing synchrotron radiation, which is an advanced X-ray source, in combination with a new-type of electrochemical reaction cell, Nippon Steel succeeded for the first time in the world in detecting the presence of Mo in local corrosion, and proposed a new mechanism to improve corrosion resistance using polymerized molybdate. In designing a corrosion-resistant alloy of stainless steel, it is very important from an engineering standpoint to develop a technique to estimate the life of stainless steel against pitting and crevice corrosion. Pitting/crevice corrosion refers to the condition of the anodic part where local corrosion develops with the surrounding cathodic part existing separately at the stainless steel surface. Source


Uemori R.,Tube and Shape Research Laboratory | Hasegawa Y.,Tube and Shape Research Laboratory | Hara T.,Kimitsu R and D Laboratory | Inoue T.,Tube and Shape Research Laboratory | And 3 more authors.
Nippon Steel Technical Report | Year: 2012

Oil, coal and natural gas, which are fossil fuels, account for the great majority of energy resources. Therefore, it is extremely important to produce and transport them at reasonable cost. In particular, high-performance steels are indispensable for the production and transportation of crude oil and natural gas. They include the development of new steels with superior high-temperature strength, new corrosion-resistant steels for boilers that use heavy oil or biomass as their fuel, and the study of thicker heavy-section steels with greater strength and toughness which allow for an increase in the hydroelectric power generating capacity of dams. In industries such as thermal, nuclear and hydroelectric power generation, positive efforts have also been made to enhance the performance of steels. They include the development of new steels with superior high-temperature strength, new corrosion-resistant steels for boilers that use heavy oil or biomass as their fuel, and the study of thicker heavy-section steels with greater strength and toughness which allow for an increase in the hydroelectric power generating capacity of dams. Source


Tsuru E.,Tube and Shape Research Laboratory | Agata J.,Tube and Shape Research Laboratory | Nagata Y.,Tube and Shape Research Laboratory | Shirakami S.,A-D Technologies | Shinohara Y.,Tube and Shape Research Laboratory
Nippon Steel Technical Report | Year: 2013

New guideline is required in forming high strength steel line pipes since springback is quite higher than that of the conventional materials. Moreover, line pipes have plastic anisotropy, which the work hardening coefficients are different between the longitudinal and the circumferential direction, caused by the forming strain and the strain aging during the heating in anti-corrosion coating. However, the effect of the plastic anisotropy on the pipe performance has not been clarified. This paper describes the numerical simulation models of the UOE pipe forming and the pipe bending with two different yield functions, which are capable of representing the plastic hysteresis and the orthogonal anisotropy respectively. The forming models introduce the operating guidelines corresponding to the material strength and the design indexes of the apparatus to aid the lack of the press capacity. The bending models reveal that yield point elongation on stress vs. strain curve in the circumferential direction in addition to the longitudinal direction degrades the buckling resistance and the decreasing rate is dependent on internal pressure. Source

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