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Volume 28, Issue 2
Displaying 1-8 of 8 articles from this issue
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Kiyoshi KAMEI1978 Volume 28 Issue 2 Pages 55-56
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
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Toshiyasu FUKUI, Hideo YOSHIDA, Yoshio BABA1978 Volume 28 Issue 2 Pages 57-65
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSStress-corrosion cracking at plate-edge of fillet weld is influenced by the distance from weld to plate-edge L, plate thickness T, small amount of additional elements, temper of base metal and test circumstance. No stress-corrosion cracking occur if L≥20mm(L/T≥1 in 20mm thick plate). Stress-corrosion cracking takes place at surface side of 1/41/5 of plate thickness having residual stress more than 810kg/mm2 and corresponding to the region of revrsion caused by weld heat input. No stress-corrosion cracking occur in the overaged region even if higher residual stress exists. Stress-corrosion cracking tends to occur most in T4 temper and least, in T7 one, though the effect of tempers of T4, T6 and T7 is comparatively small. The addition of small amount of copper is considerably effective to prevent stress-corrosion cracking.View full abstractDownload PDF (2022K) -
Koichi MURAKAMI, Eiichi SATO1978 Volume 28 Issue 2 Pages 66-69
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe impedance of films on magnesium electrodes anodized in various concentrations of Na2Cr2O7 solutions using an A. C. bridge. The corrosion potential becomes noble with time in 0.5M and 1.0M Na2Cr2O7, but not in 0.1M Na2Cr2O7. The fact is attributed to the thickness of films. Although the current density in polarization curves simply increases, the series capacitance component of the impedance has a minimum at approximately -0.65V (vs. Hg/Hg2SO4 in 1NH2SO4), and its resistance component also has a maximum at the same potential. These phenomena may be attributed to the change of film thickness. The film is easily formed in 0.5M Na2Cr2O7. When magnesium electrodes are anodically oxidized under potentiostatic conditions in 0.5M Na2Cr2O7, the film is easily formed at -0.70V.View full abstractDownload PDF (600K) -
Fumio MORIMUNE, Hideo SHINGU, Kojiro KOBAYASHI, Ryohei OZAKI1978 Volume 28 Issue 2 Pages 70-78
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe correlation between the grain size and the size distribution of TiB2 aggregates in aluminum treated with five Al-Ti-B refiners having different refining capacity was studied. Static and isothermal holding of the liquid leads the sedimentation of nucleating sabstances such as TiB2. Stirring the bottom liquid reactivates the refining potency of TiB2. TiB2 aggregates are often found at the center of petal-like patern in dendrites. TiB2 particles are dispersed in refined aluminum in the form of aggregates of smaller particles. The size distributions of the aggregates follow one or two modes of log-normal distribution. The calculated number of TiB2 aggregates reaches 106 to 10 7 per 1cm3 in aluminum containing 0.1wt%Ti. The number of cast grains is nearly proportional to the number of TiB2 aggregates. There are alont 100 TiB2 aggregates in a cast grain.View full abstractDownload PDF (2170K) -
Shigenori HORI, Toshio KONDO, Susumu IKENO1978 Volume 28 Issue 2 Pages 79-84
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSPrecipitation and hardening of the chill cast alloys during aging were studied by means of hardness measurements and metallography. Decomposition of the supersaturated solid solution during aging occurs by forming a spherical intermediate cubie Al3Zr phase with Ll2 type crystal structure. The spherical particles are slowly coarsened and then preferentially grow along the definite directions in the same manner as in the aging process of subperitectic Al-Zr alloys. A small addition of Si remarkably accelerates precipitation of the alloy. An addition of Si increases the maximum hardness. The time required for 90Å of precipitate radius vs aging temperature was determined. The resulting Arrhenius plots yield activation energies for diffusion of Zr in Al ranging from 51 to 52 kcal/mol over the composition range.View full abstractDownload PDF (1315K) -
Makoto TSUKUDA, Kumio TAKADA, Koichi OZAKI1978 Volume 28 Issue 2 Pages 85-92
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSCommercial D. C. billets 500mm in dia. of 99.8% aluminum, 2014, 4032, 5083, 6061, 7075 and Al-21%Si alloys were tested. Flow stress-strain curves were determined in uniform compression tests at a constant ram speed 3.3mm/sec at temperatures from room temperature to 500°C. The forgeability of the alloys were evaluated comparing the flow stress at a strain 0.4 and the temperature in which temperature rise caused by plastic deformation is corrected. The forgeability is improved with increase in the homologous temperature (working temperature T°K/solidus temperature Tm°K). The forgeability of the alloys are arranged for two homologous temperature ranges below 0.65Tm and above 0.75Tm. The arrangement in the order of better forgeability is; at T<0.65Tm… 6061, 4032, W-21, 7075, 5083 and 2014, and at T>0.75Tm…6061, 4032, W-21, 2014, 5083 and 7075.View full abstractDownload PDF (1704K) -
Mototaro SATO, Yoshio KATO, Kazuhiro TSUTIYA1978 Volume 28 Issue 2 Pages 93-97
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAn orthogonal cutting test was carried out on the work-pieces having various inclinations to the rolling direction on the view-point of anisotropy. Relations between the inclination to the rolling direction and cutting force, shear stress and shear angle were examined. Hill's theory was applied for analysis. The specific cutting force Ks and shear stress τs periodically change with change of the inclined angle to the rolling direction θ. But the periodic change of Ks and τs are disturbed at the rolling reduction 60% or less. The periodic change of shear plane angle φ has a reverse phase against the Ks and τs curve. The analysis of shear plane angle by Hill's theory is qualitatively in good agreement with the experiment. The shear stress, however, is unexplainable on the basis of Hill's theory.View full abstractDownload PDF (683K) -
Tsukasa IWANAMI, Masato FUJITA, Hirotake USUI, Toshio SHIMOSE1978 Volume 28 Issue 2 Pages 98-106
Published: February 28, 1978
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (2370K)
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