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Volume 34, Issue 1
Displaying 1-7 of 7 articles from this issue
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Study of mechanism of PWHT embrittlementYukihiko HORII, Shigeru OHKITA, Kazuhiro KOJIMA1996 Volume 34 Issue 1 Pages 3-7
Published: January 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSPWHT (Post Weld Heat Treatment) embrittlement phenomena were reported in the previous paper. PWHT embrittlement was found to occur along austenite grain boundaries. In this paper, mechanism of the PWHT embrittlement and the effect of alloying elements on the embrittlement are discussed.
Main conclusions derived are as follows:
1) Two types of PWHT embrittlement are observed. One is precipitation embrittlement at PWHT temperature. The other is temper embrittlement upon cooling after PWHT. Precipitation of carbonitrides and the segregation of phosphorus along austenite grain boundaries are observed in both cases.
2) Decrease in C, N and P contents improves the notch toughness of welds after PWHT. Ni is effective to increase the tensile strength of welds without the PWHT embrittlement.View full abstractDownload PDF (4492K) -
Yutaka TSUCHIDA, Yasuhiro NARUOKA, Yoshikuni TOKUNAGA1996 Volume 34 Issue 1 Pages 9-15
Published: January 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe resistance to SOHIC (stress oriented hydrogen induced cracking) has been examined in ASTM A516 Grade 70 steel plate, a popular steel plate for pressure vessls of oil refinery. The results have been discussed with the possible dominating factors, viz, hardness values of ferrite and pearlite, that were proposed in the previous paper.
Increase of cooling rate from ausutenizing resulted the improvement of the SOHIC resistance through both increasing ferrite hardness and decreasing pearlite hardness, until MA (Martensite-Austenite) constituent appears around 100°C/ min. The resistance was imporved by PWHT (Post-Weld Heat Treatment) through the favorable change in the hardness of ferrite and pearlite. This is not always true; it is dependent on the contents of precipitation hardening elements or the amount of MA constituent.View full abstractDownload PDF (5779K) -
Effect of oxide layer on titanium surface on bonding strength of titanium clad steel by hot roll bondingKazuhiro OGAWA, Yuichi KOMIZO, Masanori YASUYAMA, Hisasi IKEZAKI, Jun- ...1996 Volume 34 Issue 1 Pages 17-24
Published: January 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSThe effect of surface oxide layer on the titanium before bonding on the bonding strength of titanium clad steel by hot roll bonding was investigated from a view point of microstructure of the bonding interface. The bonding test of iron and titanium by hot roll bonding at 850°C was conducted under the various surface conditions of titanium plate such as as-recieved, oxidized or machined. The mechanical properties of clad steel was evaluated in terms of tensile test in the rectangular direction to the bonding interface and obsevation of microstructures of bonding layer. As results, the bonding strength deteriorated remarkably in the clad steel produced using the titanium having oxide layer on the surface comparing with that using the machined surface of titanium. In the clad steel produced using the titanium with surface oxide, uncontinuous intermetallic compound was observed at the interface of β-Ti and Fe, while in the clad steel produced by the titanium without surface oxiside, no remarkable intermetallic compound was observed. Oxide layer on the titanium surface promotes the formation of intermetallic compound of titanium and iron at the bonding interface and deterioration of bonding strength. Such oxide layer, however, was found to be not an obstacle to the accomplishment of metallurgical bonding.View full abstractDownload PDF (8095K) -
Kiichi TSUJI, Kotoji ANDO1996 Volume 34 Issue 1 Pages 25-32
Published: January 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSFracture toughness of fine ceramics depends on notch root radius, crack length and grain size. In this study, fracture toughness tests using three-point bend specimens of HP sintered alumina with a notch were carried out to studied the effects of notch root radius on fracture toughness and crack initiaiton sites. The notch root radius was varied in size ranging from 0.02mm to 1.0mm. The tests were also conducted at room temperature and high temperature (1000°C) to examined the influence of temperature. The results were discussed based on the process zone size fracture criterion. The relationships between notch root radius and fracture toughness measured at both room temperature and high temperature were in good agreement with the theoretical relations deduced from the criterion. Most of crack initiation sites were observed in the vicinity of the notch front.View full abstractDownload PDF (5180K) -
Hiroshi MIMURA, Kazuya ADACHI1996 Volume 34 Issue 1 Pages 33-38
Published: January 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSA study was made to clarify the cause of difference in scatter among various test methods, such as COD test and Charpy V-notched impact test, by testing the same outer sized specimens having various types of notch, i.e. fatigue notch, machine notch or V notch, under static and/or dynamic loading condition. Toughness value was measured repeatedly at a temperature in the transition temperature range. It was found that the notch acuity and the strain rate are the main factors controlling scatter of the toughness at the temperature. If scatter of the toughness is converted into scatter of transition temperature by using the proper transition curve, the effect of strain rate is more pronounced. The transition temperature for the static fracture toughness was shown to have much wider scatter than that of the fracture toughness for crack propagation.View full abstractDownload PDF (665K) -
Saburou NASU1996 Volume 34 Issue 1 Pages 39-47
Published: January 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSRecent progress of the high pressure Mössbauer spectroscopy using a diamond anvil cell has been reviewed. Principles of the Mössbauer spectroscopy have been presented briefly and results obtained for one of the common iron oxides, magnetite (Fe3O4), under high pressure up to 74 GPa have been discussed.
Recent success of the high pressure Mössbauer spectroscopy by nuclear resonant forward scattering with synchrotron radiation has also been presented and emphasized its importance in material research.View full abstractDownload PDF (976K) -
Masanori KAWAHARA1996 Volume 34 Issue 1 Pages 48-51
Published: January 25, 1996
Released on J-STAGE: August 05, 2010
JOURNAL FREE ACCESSDownload PDF (423K)
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