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Volume 40 (2002)
- Issue 6 Pages 310-
- Issue 5 Pages 262-
- Issue 4 Pages 174-
- Issue 3 Pages 114-
- Issue 2 Pages 56-
- Issue 1 Pages 4-
Predecessor
Volume 40, Issue 6
Displaying 1-5 of 5 articles from this issue
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Hiroshi MIMURAArticle type: Original paper
2002 Volume 40 Issue 6 Pages 310-316
Published: 2002
Released on J-STAGE: May 15, 2003
JOURNAL FREE ACCESSScatter of fracture strength is well expressed by the Weibull distribution.
In the present paper, three methods are proposed to evaluate dependence of the scale parameter of the Weibull distribution on plastic strain. Wide variation is found in the dependence thus evaluated, which may affect the critical strain for valid tranferability of the fracture strength between different shaped specimens through the Weibull stress.View full abstractDownload PDF (81K) -
Nobuhiro YOSHIKAWAArticle type: Original paper
2002 Volume 40 Issue 6 Pages 317-323
Published: 2002
Released on J-STAGE: May 15, 2003
JOURNAL FREE ACCESSA new structural reinforcement by net is devised for compressed natural gas vehicle fuel containers. The conventional composite containers are fabricated with continuous filament winding. The production efficiency is aimed at by the proposed net reinforcement with high structural reliability ensured by means of structural optimization technique. The net is modeled as truss structure contacting with the surface of the metallic liner, which is modeled as elastic solid finite elements. The geometrical nonlinearity with the finite rotation of net members raises the shape finding problem of the net, where the position of connection node is analyzed on the basis of principle of minimum strain energy with the iterative solution searches. The cylinder part of the container is easily handled under the assumption of infinitely long cylinder, so that the net reinforcement of spherical dome is taken into consideration. The optimum length of net member is determined so as to realize uniform strain in net members. A formulation of the sensitivity analysis is derived to constitute the governing equations to determine the optimum length, and the equations are summarized in linear simultaneous equations. An optimum configuration of the net is investigated through the numerical examples.View full abstractDownload PDF (178K) -
Tomoya KAWABATA, Kimihisa YUMINO, Hiroshi KATSUMOTO, Akihiko NAGAYOSHI ...Article type: Original paper
2002 Volume 40 Issue 6 Pages 324-332
Published: 2002
Released on J-STAGE: May 15, 2003
JOURNAL FREE ACCESSRecently, Ausformed Bainite type HT610 steel has been developed and its use has rapidly spread to many areas of applications as a result of a variety of advanced properties. The Ausformed Bainite steel for multi-purpose tank has many advantages as follows;
1) Gives design advantages in the use of 610N⁄mm2 class high tensile strength steel
2) Enables welding without preheating
3) Has superior toughness (high resistance to brittle fracture promoting safety)
4) Maintains its strength after heat treatment for stress relief.
5) Has high resistance to ammonia stress corrosion cracking
This report briefly shows schematic diagram of the Ausformed Bainite structure and the mechanism behind its superior properties with experimental data.View full abstractDownload PDF (438K) -
Tatsuyuki NEZU, Koji SEKINE, Yasuo OTOGURO, Masao INOUE, Kazuteru OHIS ...Article type: Original paper
2002 Volume 40 Issue 6 Pages 333-339
Published: 2002
Released on J-STAGE: May 15, 2003
JOURNAL FREE ACCESSHardness distribution, micrograph, and chemical analysis of the nitrided surface layer under various conditions were investigated for a modified 9Cr-1Mo steel. Moreover, relationships between nitriding conditions and creep rupture properties were examined.
The results obtained are as follows.
1) The hardness of the nitrided surface layer increased and nitrogen diffused inside deeper with increasing nitriding time. However, increasing nitriding time more than 24 hours had liltle effect on maximum hardness and depth of hardened layer.
2) Nitrides on the surface spalled or decomposed to diffuse inside as solved nitrogen during heat treatment after nitriding.
3) Nitriding increased markedly creep rupture strength but nitriding for longer time decreased rupture ductilities.
4) Rupture ductilities were increased by decreasing nitriding time, polishing the nitrided layer, and nickel plating on the specimen.View full abstractDownload PDF (564K) -
Takanori NAKAZAWA, Yosiyuki YAMADA, Tomohito TAKAHASHI, Masayoshi YAMA ...Article type: Original paper
2002 Volume 40 Issue 6 Pages 340-347
Published: 2002
Released on J-STAGE: May 15, 2003
JOURNAL FREE ACCESSThe effects of normalizing and tempering conditions on creep rupture properties at 650°C and hardness of 9 Cr-W-Mo steel were investigated in conjunction with changes in microstructres. The microstructures were examined with an optical and an electron microscopy and the precipitated elements were assesed by analyzing extracted residues. Creep rupture strength and hardness of tempered steels increased with an increase in normalizing temperature from 950°C to 1200°C, while they decreased with an increase in tempering temperature from 700°C to 780°C and the time from 1h to 100h. The amount of undesolved MX particles, which were observed in mormalized steels, decreased with an increase in normalizing temperature. A number of very fine MX and rod-like particles precipitated during tempering. The analysis of extracted residues showed that the amount of precipitated Nb and V in normalized steels decreased with an increase in norma1izing temperature. Fe, Cr, Mo, and W were desolved in matrix at 950°C. All of the alloying Nb and half of the V precipitated after tempering, while most of Mo and W were still in solution. Since the amounts of precipitated Nb and V after tempering were independent on normalizing temperature, the number of very fine MX particles increased with an increase in normalizing temperature. On the other hand, tempering temperature and time had no influence on precipitation behavior of very fine MX partic1es. These results suggest that mormalizing temperature dependence of hardness and creep ruptures trength is related to precipitation hardening by fine MX particles and tempering temperature and time dependence of them is related to recovery of the martensite structure.View full abstractDownload PDF (151K)
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