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Volume 30, Issue 8
Displaying 1-9 of 9 articles from this issue
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Tsuneo TAKAHASI1980 Volume 30 Issue 8 Pages 417-418
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
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Yoichi TOMII, Masamichi OKAMOTO, Masao MIZUNO1980 Volume 30 Issue 8 Pages 419-425
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSScanning electron microscopy was carried out on surfaces of aluminum alloy plates A5083 P-0 and A1070 P-0 mechanically, chemically and thermally pre-treated to explain a role of the surface pre-treatment in blow hole formation in welds. Other factors such as the arc phenomenon, thickness and composite structure of surface oxide film etc. should be taken into consideration. Residual chemical reaction products "smatt", thick oxide films formed at high temperatures and sometimes wire brushing can cause a hydrogen source to form blow holes in welding.View full abstractDownload PDF (3351K) -
Tsuneo TAKAHASHI, Yo KOJIMA, Tatsuo SATO, Takashi IDEGOMORI1980 Volume 30 Issue 8 Pages 426-431
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe early stage of aging in Al-1-15at%Ag alloys was investigated by means of electrical resistivity and specific heat measurements and X-ray diffraction method. The η'-zones are formed immediately after quenching and spherical G.P. zones are subsequently formed in the early stage of aging. The spherical G.P. zones formed at lower temperatures consist of an ordered arrangement of Ag atoms (ordered state, η-zone). Those formed at elevated temperatures, on the other hand, consist of a disordered arrangement of Ag atoms (disordered state, ε-zone). The η- and ε-zones reversibly transform from one state to another at the transition temperature. The experimental transition temperatures are 140° to 160°C for Al-1-3at%Ag alloys and 160° to 180°C for Al-5-15at%Ag alloys.View full abstractDownload PDF (1119K) -
Akio HASUMI, Yasuhiko ITOI, Eiichi SATO1980 Volume 30 Issue 8 Pages 432-436
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSA thick anodic film was formed on magnesium by anodizing in a concentrated KF solution. Sparks of electric discharge on magnesium were found in the anodizing process. The composition, characteristics and surface appearance of the film were examined by means of anodic polarization, X-ray diffraction, IRRS, interfacial impedance measurement and scanning electron microscopy. The film consists of KMgF3 and MgF2. MgF2 solved in NaCl solution reduces the corrosion rate of magnesium and acts as a film formation inhibitor. This film will protect magnesium from corrosion.View full abstractDownload PDF (764K) -
Akio HASUMI, Yasuhiko ITOI, Eiichi SATO1980 Volume 30 Issue 8 Pages 437-441
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSA thick anodic oxide film consists of an aluminum hydrate was formed on a magnesium plate by anodizing in sodium aluminate solution. Scanning electron micrography, X-ray diffraction, IRRS and interfacial impedance measurements were made to examine structural changes of the film during sealing. The corrosion resistance was examined on the basis of polarization curves. The film before sealing is of network and has a number of cracks. It consists of an aluminum hydrate Al(OH)3. This network film transforms into needle-like boehmite Al•O•OH free from cracks by sealing. Prolonged sealing results in a dense and isolating boehmite film having further resistance to corrosion.View full abstractDownload PDF (1430K) -
Keiichi KOIKE1980 Volume 30 Issue 8 Pages 442-448
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAl-Zn-Mg-Cu casting alloys containing Mg 1 to 5%, Zn 1 to 5% and Cu 1% were tested. The alloys containing Mg 3 to 5% and Zn 2.5 to 5% at a Zn/Mg ratio less than 1.17 in which α+S+T phases crystallize have high resistance to hot tearing and have higher tensile strength and elongation in the T6 condition. Solute condensation into grain boundaries has an important influence on tensile properties and hot tearing of the Al-Zn-Mg-Cu alloys. Two alloys Al-4%Mg-4%Zn-1%Cu and Al-3.5%Mg-2.5%Zn-1%Cu are practically applicable. The former has tensile strength 50kg/mm2 or more and elongation 5% or more and the latter tensile strength 44kg/mm2 and elongation 15% or more.View full abstractDownload PDF (1388K) -
Shiomi KIKUCHI, Yoshiro MOTOYAMA, Masao ADACHI1980 Volume 30 Issue 8 Pages 449-455
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSTensile tests on the <001> oriented single crystals were carried out at elevated temperatures from 623 to 873k to invertigate the deformation behavior. The deformation behavior changes from pure metal type to alloy type with increase in stress in a low stress region and vice versa in a high stress region. The stress exponent of steady state strain rate, n, is about 5 in the low stress region, about 3 in the middle stress region and 5 or more in the high stress region. The mobile dislocation density ih the steady state is expressed as: ρm=β(σ/μ)2 where σ is the applied stress, μ the shear modulus, and β depends on the deformation temperature. The general rate equation showing the relation between strain rate and steady state stress for the alloy type behavior is introduced.View full abstractDownload PDF (1219K) -
Yoshishige TSUMURA1980 Volume 30 Issue 8 Pages 456-462
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
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Makoto TSUKUDA, Koichi OZAKI1980 Volume 30 Issue 8 Pages 463-470
Published: August 30, 1980
Released on J-STAGE: July 23, 2008
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