Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 38, Issue 1
Displaying 1-11 of 11 articles from this issue
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  • OPENING ADDRESS OF THE YEAR
    Hideo OGASHI
    1988Volume 38Issue 1 Pages 1-2
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.1
    JOURNAL FREE ACCESS
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  • Influence of notch root radius on dynamic elastic-plastic fracture thoughness of high strength aluminum alloys
    Eiji KATO, Yoshisada UEDA, Toshiro KOBAYASHI
    1988Volume 38Issue 1 Pages 3-8
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.3
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    Relationship between the dynamic elastic-plastic fracture toughness and the notch root radius of high strength 7075 alloys aged in various conditions were investigated. The apparent fracture toughness is strengthened with an increase of the notch root radius, ρ, and is independent of the aging condition. The notch root radius does not affect the critical value of fracture toughness, which depends on the mean free path of the inclusions over 1μm. The experimental value of critical point is slightly higher than the calculated one.
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  • Evaluation of fracture toughness of aluminum alloys by tear test
    Toshiro KOBAYASHI, Mitsuo NIINOMI, Kouichi IKEDA
    1988Volume 38Issue 1 Pages 9-15
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.9
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    The correlation between the fracture characteristics values evaluated from the tear test and the fracture toughness values were investigated. New method to evaluate the fracture toughness was examined by the tear test. The correlation between the fracture characteristics (σin, UIEt and UPEt), which were newly defined based on the true crack initiation point in the tear test and the fracture toughness values (KIC, JIC and Tmat) evaluated by the ASTM E-399 method was studied, and a good correlation was recognized between σin and KIC, UIEt and JIC, and UPEt and Tmat, respectively. The critical stress intensity factor (KC) obtained from the precracked tear test agree well with KIC values evaluated by the ASTM E-399 method. However, KC obtained from the standard tear test is overestimated about 20% comparing with the KIC because of the effect of the notch tip radius.
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  • Measurement of heat transfer coefficient between molten Al-4.5%Cu alloy and chill blocks by melt drop method
    Shun-ichi TAKEMOTO, Hiromasa TAKEUCHI, Toshio SUZUKI
    1988Volume 38Issue 1 Pages 16-21
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.16
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    Heat transfer coefficient at metal-mold interface during die casting was evaluated by the metal drop method. Solidification time at certain positions of a specimen was measured using thermocouples. It was also numerically calculated under corresponding experimental conditions with different values of heat transfer coefficient. The values of heat transfer coefficient were determined so as for both solidification time to coincide.
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  • Effects of Mn addition on aging behavior in Al-1%Mg2Si-0.4%Si alloys
    Susumu IKENO, Kenji MATSUDA, Yasuhiro UETANI, Shizuo TADA
    1988Volume 38Issue 1 Pages 22-28
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.22
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    Aging phenomena of Al-1%Mg2Si-0.4%Si alloys containing Mn up to 0.8% were studied by means of electrical resistivity measurement, transmission electron microscopy and tensile test. With an increase of Mncontents, the aging rate once decreases and then increases at 150 and 200°C aging. At the peak aging condition at 200°C, mean spacing of precipitates once decreases and then increases with increasing Mn content. In the 0.8% Mn additional alloy aged at 250°C, the aging rate decreases as compared with that of Mn free alloy. This alloy shows absolutly low age-hardenability because extremely coarse precipitates distribute randomly in the matrix. The interface between insoluble particles and matrix act as sinks for excess vacancies, so the heterogeneous nucleation of precipitates and a decrease of aging rate occur due to reduce the excess vacancies in the matrix.
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  • Role of iron in pitting corrosion of aluminum
    Osami SERI, Kohsuke TAGASHIRA
    1988Volume 38Issue 1 Pages 29-34
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.29
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    Pitting corrosion behaviors of Al-Fe alloys in 0.1M NaCl solution were investigated by measurement of corrosion potential and the pH value of bulk solution. The corrosion potential changes from -0.6V vs. Ag/AgCl in the early stage (<100h) to -0.8V in its late stage (>200h). This shift of corrosion potential to less noble potential occurs due to the increase of Cl- ion concentration in the pit. The pH values of bulk solution changes from 5.0 to 6.0-6.5 during the long range process. The following reactions occur in the later stage;
    Fe(OH)2+2H+→Fe2++2H2O
    Fe(OH)2+2H++2e→Fe+2H2O
    Iron which exists in the form of FeAl3 plays not only a statistical role of cothodic site where the oxygen reduction occurs, but also a dynamic role in which iron in FeAl3 changes chemical forms, e. g. ferrous iron, ferrous hydroxide and deposited iron in the later stage of corrosion process.
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  • Corrosion protection of aluminum alloys by zinc diffusion layers
    Takeshi HATTORI, Masayuki HAYAKAWA, Kazuo NISHIKAWA, Shigeo SAKAI
    1988Volume 38Issue 1 Pages 35-39
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.35
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    Zinc diffusion process is very effective to corrosion protection of aluminum alloys. Most effective condition of zinc diffusion layers to corrosion protection was not clear. The relationship between the condition of zinc diffusion layer and the velocity of pitting corrosion was studied. It was found that the product of surface zinc content and diffusion depth, and gradient of zinc content in diffusion layer are very important to corrosion protection.
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  • Mathematical models for computer control of hot roughing mill of aluminum
    Hiroshi KIMURA
    1988Volume 38Issue 1 Pages 40-46
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.40
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    Mathematical models to estimate the rolling force P and the rolling torque G of hot roughing mill of aluminum were developed. These models consist of equations to calculate the rolling force function QP, the torque arm coefficient λ and the mean flow stress Kfm. The equation of QP and λ are derived empirically by analysing the rolling data. The equation of Kfm is based on the empirical expression of the experimental data by complastometer. Almost satisfactory accuracy is achieved in estimating P and G. The calculating method to obtain the pass schedule in the restrictions of rolling force, rolling torque, angle of biting etc. was developed. The total number of passes reduces and the productivity of roughing mill for aluminum alloys increases by using this new pass schedule.
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  • Effects of aging treatment and rolling process on anodic polarization behaviors of Al-Zn-Mg alloys
    Tetsuo INOUE, Takeo SHINODA, Takeo OKI
    1988Volume 38Issue 1 Pages 47-53
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.47
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    Aging behavior and electrochemical polarization characteristics of Al-Zn-Mg alloys sheets and castings containing Cu, Cr, Si and Ti up to 0.1 at% were investigated. The HV values of sheets are 110-120 which are higher 20-30 than those of castings. Grain size of sheets decrease with increases of element contents, especially in the addition of Ti. Pitting potential in 0.5N NaCl solution changes toward to noble value with increases of additional contents, especially in the sheets contained Cu. Passivation current density reduces with increases of additional contents. The pitting potential changes toward to noble value and the passivation current density reduces with increase of aging time, respectively. These phenomena are explained by correspondance of change of solute quantity of Zn and/or Mg on the surface.
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  • Measurement of dendrite arm spacing
    Japan Institute Of Light Metals, Committee Of Cast
    1988Volume 38Issue 1 Pages 54-60
    Published: January 30, 1988
    Released on J-STAGE: November 05, 2008
    DOIhttps://doi.org/10.2464/jilm.38.54
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  • Present status and future prospects of fine ceramics
    Junichi SATO
    1988Volume 38Issue 1 Pages 61-70
    Published: January 30, 1988
    Released on J-STAGE: July 23, 2008
    DOIhttps://doi.org/10.2464/jilm.38.61
    JOURNAL FREE ACCESS
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