National Research Institute For Metals Research Articles

Dawn of Magnetic Refrigerant Research at the National Research Institute for Metals

Dawn of Magnetic Refrigerant Research at the National Research Institute for Metals

Calculation of Reloading Stress Relaxation Behavior Based on Creep Equations for 1Cr-0.5Mo-0.25V Steel

In order to analyze the stress relaxation behavior under repeated loadings for 1Cr-0.5Mo-0.25V steel, a stress relaxation model based on creep equations has been developed. The model was implemented into the ANSYS finite element program in terms of user define material model. The calculated results were compared to the observed results of uniaxial reloading stress relaxation testing, which were performed by the National Research Institute for Metals of Japan (NRIM) for 1Cr-0.5Mo-0.25V stainless steel bolting material at 500°C. It was shown that the proposed model could be applied for the present data. The calculated residual stresses versus time curves were in good agreement with the observed for initial stress level of 297.1MPa at 500°C and for specific reloading time intervals of 24, 72, 240, and 720 hours.

Reloading Stress Relaxation Behavior Analysis Based on a Creep Model for High Temperature Bolting Steel

An analytical method based on a creep model is being developed to investigate the effect of retightening on stress relaxation behavior for high-temperature turbine and valve studs/bolts. In order to validate the approach, the calculated results are compared to the results of uniaxial reloading stress relaxation testing, which were performed by the National Research Institute for Metals of Japan (NRIM) for 12Cr-1Mo-1W-1/4V stainless steel bolting material at 550°C. It was shown that the proposed model based on Altenbach-Gorash-Naumenko creep model for the primary and steady state creep could be applied for the present data. The calculated residual stresses versus time curves were in good agreement with the measured for initial stress level of 273.6MPa at 550°C and for specific reloading time intervals of 24, 72, 240, and 720 hours.

Cutting-Edge Technology of Bismuth-Based High-Temperature Superconducting Wires for Application in Energy- and Environment-Related Fields

The first bismuth-based superconductor was discovered by Dr. Maeda of National Research Institute for Metals (currently, National Institute for Materials Science) in 1988. Since then, Sumitomo Electric Industries, Ltd., has been attempting to improve the fabrication method of superconducting wires and to develop products applying bismuth-based superconductors. As a result, the length of wires that can be fabricated has steadily increased as well as the wire performance, and these achievements have led to the practical use of prototype products and demonstration projects worldwide. Bismuth-based superconducting wires were established as an industrial material along with the development of an over pressure sintering method. In addition to this industrial accomplishment, these wires are now ready for practical use in application fields such as power cables and large-scale motors for ships. Superconductivity is an ultimate energy-saving technology, and its practical utilization is expected to contribute to the reduction of CO2 emission and the prevention of global warming.

Japan Watch - Corrosion Studies in Ultra-Steel Project at NIMS in Japan

Since 1997, the National Institute for Materials Research (NIMS, formerly National Research Institute for Metals) in Japan has promoted a project for R&D of innovative steels, under the name of Ultra-Steel. The project covers such fields as 800MPa class steels for welding construction, 1500MPa ultra-high strength steels resistant to hydrogen brittleness, advanced heat resisting steel for ultra-super critical power plants and advanced corrosion resistant steels for marine environments.

Magnetic separation using superconducting magnets

Since the 1970s, magnetic separation has been increasingly used for purification of liquids, such as heavy-metal ion removal from laboratory waste water, purification of kaolin clay in the paper-coating industry, waste water recycling in the steel industry, and recycling of glass grinding sludge in cathode-ray tube polishing factories. In the 1980s, large superconducting magnets were adopted for the field coils of high-gradient magnetic separation systems used for kaolin clay purification. After the development of liquid-helium-free superconducting magnets in the 1990s, new national research projects were initiated in Japan to expand the application of superconducting magnetic separation to other areas. This paper discusses some of the fundamental characteristics of magnetic separation, the progress of superconductorization (use of superconducting magnets as field coils in magnetic separation systems) and recent R&D activities at the National Research Institute for Metals in Japan.

わが国の腐食コスト

The first report on the cost of corrosion in Japan had been published at 1977. The report estimated that the corrosion loss in Japan which did not include indirect loss was 1-2 percent of Gross National Product (GNP) at that time. Since then, almost two decades have been passed and the industrial structure has drastically changed. Corresponding to this situation, the committee on the cost of corrosion in Japan was organized at 1999 jointly by Japan Society of Corrosion Engineering (JSCE) and Japan Association of Corrosion Control (JACC). The project was funded by the National Research Institute for Metals (NRIM) in the program of the Ultra-Steels (STX-21) Project. Cost of corrosion at 1997 was estimated by the Uhlig method and the Hoar method. The estimated cost was compared with the past data which was estimated at 1974 by the same Uhlig and Hoar method. In addition to the above estimation, the preliminary analysis by the Input/Output method is performed for estimating the total cost of corrosion including the direct and indirect cost. The overall cost estimated by the Uhlig and Hoar method at 1997 was found to be 3, 938 billion yen and 5, 258 billion yen, respectively, which is equivalent to 0.77% and 1.02% to GNP of Japan. The total cost including the direct and indirect cost, which is estimated preliminary by the Input/Output analysis, is likely to be more than 2 times larger than the direct cost estimated by the Uhlig method.

酸化物系金属系ハイブリッドマグネットのクエンチ保護方法

Development of a 1 GHz-class NMR magnet system is going on at the Tsukuba Magnet Laboratory of the National Research Institute for Metals. This magnet will consist of the inner HTS coil and the outer LTS magnet, it is designed to generate a magnetic field of 23. 5 T. We are planning to operate the inner HTS coil and the outer LTS magnet in series in order to obtain high stability of the central magnetic field. To achieve the stability of 0. 01 ppm/h, the critical current of the inner HTS coil must be four times as high as the operating current. Simulation results of usual quench protection methods suggest that there is some possibility that the inner HTS coil is damaged when a quench occurs in the outer LTS magnet. We designed a new quench protection circuit for the 1 GHz-class NMR magnet and confirmed its adequacy using quench simulation codes. Our new method is valid for any HTS-LTS hybrid magnet.

Recent advances in high-field magnets at TML

The Tsukuba Magnet Laboratory (TML) of the National Research Institute for Metals has been producing epoch-making achievements in the history of high-field magnets. Its hybrid magnet is in operation, providing users with fields up to 30 T in a 52-mm∅ room-temperature bore. In September 1999, the hybrid magnet generated a field of 37.3 T in a 32-mm∅ room-temperature bore, which was the world record of the steady-state fields at that time. The superconducting magnet system operating at TML succeeded in generating 23.4 T using two Bi-2212 insert coils. As a milestone in the 1 GHz NMR magnet project carried at TML, a 900 MHz NMR magnet was successfully manufactured and operated in a persistent mode. A challenging program in which different types of superconducting magnets are developed to meet specific requirements is in operation. One example is a magnet designed to generate uniform magnetic force fields defined as B grad B in a sample space. TML is now a user facility open to domestic and international users. Efforts will be continued to improve its high-field facilities by developing magnet technology as well as materials for high-field magnets.

Application of the distributed database (Data-Free-Way) on the analysis of mechanical properties in neutron irradiated 316 stainless steel

A distributed database system named ‘Data-Free-Way’ for advanced nuclear materials has been developed by the National Research Institute for Metals (NRIM), the Japan Atomic Energy Research Institute (JAERI), the Japan Nuclear Cycle Development Institute (JNC), and the Japan Science and Technology Corporation (JST) under a cooperative agreement. In this paper, features and functions of the system including input data, are described together with a method to share the database among the four organizations as well as examples of the easy accessible search of material properties provided by the system. Results of an analysis of tensile and fatigue properties data on type 316 stainless steel collected by the different organizations and stored in the present system are introduced as an example of attractive utilization of the system. In addition to show the capability of the system some WWW server sites of the Data-Free-Way are introduced with respect to information supply on nuclear materials.

Tertiary creep behaviour of a new single crystal superalloy at 900°c

*National Research Institute for Metals, 1-2-1 Sengen Tsukuba-shi, Ibaraki, Japan**CNR—TEMPE, Via R. Cozzi 53, 20125 Milano, Italy(Received April 10, 2000)(Accepted in revised form May 22, 2000)Keywords: Nickel alloy; Creep; MicrostructureIntroductionFor temperatures/stresses that are relevant for the service, the shape of creep curves in nickel basesuperalloys is dominated by an extensive tertiary behaviour over most of the life, rather than a dominantsteady state. To describe such accelerated creep behaviour a strain, rather than a time–softening,approach [1] appears to be more appropriated. For single crystal or, in general, directionally solidifiednickel base superalloys, the following linear strain softening relationship is often utilized [2–4]:e˙5 e˙8~1 1 Ce! (1)where e˙ is the instantaneous strain rate, e˙° is the strain rate at the beginning of tertiary creep,eis thetertiary creep strain and C is a damage coefficient, generally depending on stress and temperature,which leads to a progressive increase in the creep rate with the accumulated creep strain.The Eq. 1 is also utilized in the uconcept methodology, in fact its analytical solution is identical tothe portion of the uconcept function [5] describing the tertiary creep with u

Absence of a step-edge barrier on a polar semiconductor surface with reconstruction

National Research Institute for Metals, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan~Received 9 December 1999!Based on purely geometrical considerations, we point out that a polar semiconductor surface with recon-struction does not satisfy the necessary condition for the existence of an Ehrlich-Schwoebel~ES! step-edgebarrier. We further show by the explicit Monte Carlo calculations that the kinetic surface roughening observedon a GaAs~001! surface can be accounted for by the stability and complexity of the (234) reconstruction, andhence an ES barrier is unnecessary to account for it. Finally, we point out that it is incorrect to use thesolid-on-solid~SOS! model with an ES barrier for surface growth studies or for atomistic growth simulations.I. INTRODUCTION

Bi-2212/Ag high-field magnets

Bi-2212/Ag conductors show practical transport properties in high magnetic field regions above 20 T and 4.2 K, where it is considered difficult to use metallic superconductors. In this paper, the recent progress of our development of Bi-2212/Ag high field insert magnets is presented. Bi-2212/Ag stacked double pancake coils with a 49–150 mm outer diameter, 15–65 mm inner diameter and 50–220 mm height have been fabricated and tested in a superconducting backup magnet system up to 18 T at the Tsukuba Magnet Laboratory of National Research Institute for Metals (NRIM). The Bi-2212 insert magnets successfully generated 5.42 T with a backup field of 18 T, i.e. the total magnetic field of the superoconducting magnet system reached 23.42 T, which is the highest magnetic field ever achieved by a superconducting magnet.

Generation of 23.4 T using two Bi-2212 insert coils

Development of a 1 GHz superconducting NMR magnet is in progress at the Tsukuba Magnet Laboratory (TML) of the National Research Institute for Metals (NRIM). This magnet will contain a BSCCO inner coil, which should generate a central field of 23.5 T in a backup field of 21.1 T. In order to accomplish this targeted field, we fabricated two Bi-2212 double-pancake coils (Coil A and Coil B). They were installed in the high-field superconducting magnet system at the TML/NRIM. Their performance was measured in a backup field of 18 T. Coil A was made of 20 double-pancakes wound with Ag sheathed Bi-2212 tape conductors. Ag-Mg tape was co-wound for mechanical support. Its winding was 147 mm in outer diameter and 220 mm in height. It generated a central field of 21.4 T in a clear bore of 61 mm. Coil B was located inside Coil A. Its 6 double-pancakes were wound with Bi-2212 tape conductors reinforced with Ag-Mg-Ni alloy sheath. The outer diameter and height of the winding were 48 mm and 63 mm, respectively. Coil B generated the highest field of 23.4 T in a backup field of 21.4 T. This study confirmed that the present performance of the Bi-2212 coils had already satisfied the required conditions for the inner coil of the 1 GHz NMR magnet from the viewpoint of high-field generation.

超伝導工学データベース事始め

We have developed a database for high magnetic field science and technology. Tsukuba Magnet Laboratory (TML) of the National Research Institute for Metals (NRIM) holds one of the world's leading high magnetic field facilities, incorporating external scientists from around the globe. We have established cooperative relationships with other high magnetic field laboratories worldwide. The NRIM is also a central organization of VAMAS activities for the standardization of measurement methods for superconductive materials. The database contains experimental results obtained at our facilities, standard references given by VAMAS and technological information provided by high magnetic field laboratories. However, from the user's point of view the database should be global, preferably including other fields of superconductivity and cryogenics. We will embody up-to-date results reported in symposiums, conferences and journals, and bring together existing data scattered throughout different sources into our database. We call it the “Engineering Database for Applied Superconductivity and Cryogenics”. Our system also includes “Reference Database” dealing with data sources, and “Technical Terms Database” as a thesaurus of the technical terms used in the field of superconductivity and cryogenics. The database can be accessed from around the world through the Internet using a web browser. This project will be conducted in cooperation with the Cryogenic Association of Japan. We would appreciate researchers' contributions to the engineering database.

Calculation of Stress Relaxation Properties for Type 422 Stainless Steel

Analytical life prediction methods are being developed for high-temperature turbine and valve studs/bolts. In order to validate the approach, the calculated results are compared to the results of uniaxial stress relaxation testing, bolt model testing, and service experience. Long time creep, creep-rupture, and stress relaxation tests were performed by the National Research Institute for Metals of Japan (NRIM) for 12 Cr-1 Mo-1 W-1/4V, Type 422 stainless steel bolting material, at 500, 550, and 600°C. Based on these results and limited tests for a service-exposed bolt, the creep behavior can be described using a two-parameter material model: ε/εr=1−1−t/trm+1δ where εr is the rupture strain, tr is the rupture time, and m and δ are material constants. For comparison with the measured uniaxial stress relaxation properties, the stress relaxation was calculated using the two-parameter creep equation and a strain-hardening flow rule. The rupture time data was correlated using time-temperature parameter methods. A power law was used for the rupture strain versus rupture time relationship at each temperature. The calculated stress versus time curves were in good agreement with the measured at all temperatures and for initial strain levels of 0.10, 0.15, 0.20, and 0.25 percent. [S0094-9930(00)01701-7]

Tsukuba develops key role in Japan's research efforts

Tsukuba Science City is home to many of Japan's leading research institutes and is playing a key role in the country's development of low dimensional structures. Among the organizations doing important work in this area are the National Research Institute for Metals and the Institute of Materials Science at the University of Tsukuba.

Superconducting magnets for generating uniform magnetic force field

We report a new application of high magnetic fields to structural biology. We usually design and fabricate a magnet to achieve uniform magnetic field as well as uniform magnetic field gradient. In this new application we adopt a uniform magnetic force field. It has been found that the growth of protein crystals is affected by the presence of magnetic force. Development of uniform magnetic force field magnets is now in progress at the Tsukuba Magnet Laboratory of the National Research Institute for Metals. These magnets are superconducting magnets because they must be continuously run for several days to grow protein crystals. The first magnet wound with NbTi is now under installation. This magnet is designed to generate a uniform force field of 240 T/sup 2//m in a cylindrical space of 10 mm in diameter and 10 mm in height, and the magnetic force field fluctuation along z-direction is better than 0.4%. In liquid helium, it could achieve the design current.

Development of 1 GHz superconducting NMR magnet at TML/NRIM

Development of a 1 GHz superconducting NMR magnet is in progress at the Tsukuba Magnet Laboratory of the National Research Institute for Metals. The magnet will consist of two parts. The outer magnet of LTS coils is designed to generate a field of 21.1 T (900 MHz) in persistent current mode. The inner coil is designed to generate an additional 2.4 T, resulting in a central field of 23.5 T (1 GHz) in a 54 mm diameter bore at room temperature. As a high-resolution NMR magnet, field stability as well as field homogeneity is very important, which is especially difficult to achieve in the inner coil when exposed to extremely high magnetic fields that superconducting magnets have not yet encountered. The engineering design is complete and fabrication of the superconductors has begun. This report presents the results of the engineering design and R&D studies on the candidate superconductors for the inner coil, such as BSCCO, and improved Nb/sub 3/Al and Nb/sub 3/Sn.

Present status of Data-Free-Way (distributed database system for advanced nuclear materials)

The National Research Institute for Metals (NRIM), the Japan Atomic Energy Research Institute (JAERI), the Power Reactor and Nuclear Fuel Development Corporation (PNC), and the Japan Science and Technology Corporation are jointly developing a distributed database for advanced nuclear materials named Data-Free-Way. The main objective of the development is to share fresh and stimulating information as well as accumulated information for the development of advanced nuclear materials, for the design of structural components, etc. This paper describes the present status of the system and examples of utilization of the system. From such examples, it is demonstrated that the present distributed database system is attractive to evaluate materials performance in the fusion environment.