Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
Search
Advanced search
OR
Browse
Search
Volume 49, Issue 10
Displaying 1-9 of 9 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
RESEARCH REPORT
  • Prediction of porosity content in Al–4.4 mass%Mg DC slab
    Hiromi NAGAUMI
    1999 Volume 49 Issue 10 Pages 471-475
    Published: 1999
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.49.471
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    A new method for predicting porosity contents in Al–4.4%Mg DC sheet ingot (slab) was proposed. Hydrogen supersaturated mass in the interdendritic liquid and the pressure drop were taken into account for the porosity prediction. Using the method, the porosity contents were calculated and they well agreed with the experimental results. So it became possible to predict the porosity contents in the slab quantitatively. The effects of parameters such as thermal gradient, cooling rate, local equivalent pressure and initial hydrogen on the porosity contents were analytically investigated, and the distribution of porosity and porosity contents in the slab of Al–4.4%Mg alloys were determined. The following conclusions were obtained, (1) The porosity contents decrease with increasing the thermal gradient and cooling rate. But when the thermal gradient and the cooling rate are higher than 5000 K/m and 5.0 K/s, respectively, the porosity contents become almost invariable. When the thermal gradient and the cooling rate are lower than 2500 K/m and 1.0 K/s, respectively, the porosity content rapidly increase. (2) The lower the initial hydrogen contents, the lower the porosity contents become. (3) The controls of the local equivalent pressure and initial hydrogen content are necessary to reduce the porosity formation in the DC slab. (4) The distribution of porosity contents in the slab corresponds to the distribution of DAS. As the DAS becomes coarse the porosity contents become high.
    View full abstract
    Download PDF (881K)
  • Resistivity increment by solute vanadium in aluminum
    Takeshi IKEDA, Tatsunari MIYASHITA, Takanori HIRAI, Masahiko IKEDA, Sh ...
    1999 Volume 49 Issue 10 Pages 476-480
    Published: 1999
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.49.476
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The contribution per unit concentration of solute vanadium to electrical resistivity of solid aluminum, ΔρV, and its temperature dependence were measured using high purity Al–V binary alloys. ΔρV at 77 K and 300 K are 37.6 and 37.0 nΩm·mass%−1, respectively, showing a small negative DMR (deviation from the Matthiessen's rule). After a prolonged heat treatment at 923 K, the decrease in the actual size factor due to oxidation of the specimen surface was observed. In the heat treatment temperature-resistivity (TH–ρ) diagram, the resistivity of Al–V binary alloy calculated from reported equilibrium solubility values locates between those of Al–Ti and Al–Zr alloys. Since the large Δρ and very small diffusivity in aluminum, the vanadium content should be especially restricted in manufacturing or recycling processes of aluminum conductor alloys.
    View full abstract
    Download PDF (668K)
  • Aging characteristics and tensile properties of Mg–Y–Nd alloys
    Shotaro MOROZUMI, Hiroshi SAIKAWA, Kin-ichi KOYAMA, Masato OTSUKI
    1999 Volume 49 Issue 10 Pages 481-486
    Published: 1999
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.49.481
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The effects of small amounts of Ce, Mischmetal (Mm), Nd and Zr additions on the age-hardenability of Mg–1.5%Y and Mg–9%Y alloys were investigated. The tensile test properties and creep behavior of the alloys were also examined. The addition of about 2% Ce or Mm to the Mg–1.5%Y alloy has no effect to improve its age-hardenability, but has the effect to increase the matrix hardness. The essential effect of 0.5% Zr addition is the grain refinement of the alloy. The addition of 2% Nd has a significant effect to increase age-hardening of the alloy due to the precipitation of Nd itself. The Nd addition also greatly improves the age-hardenability of the Mg–9%Y alloy due to the cooperative precipitation Nd and Y. The cast and T6-treated Mg–10%Y–2%Nd alloy was short-time tensile tested at 573 to 723 K at two different initial strain rates of 2.78 × 10−5 and 2.78 × 10−4 and creep-tested under the stresses of 5 to 50 MPa. All of the results are expressed by the equation, ε∞σn, where ε is the initial strain rate or steady creep strain, σ is the 0.2% yield stress or creep stress, and n is a constant of about 5 or more in the present alloy. The hot-rolled and T6-treated Mg–9%Y–2%Nd alloy was also short-time tensile tested at 623 to 773 K at various initial strain rates. The results obtained are also expressed by the same equation above, where n is about 6 at all the test temperatures, except about 4 at 773 K.
    View full abstract
    Download PDF (1421K)
  • Formation mechanism of surface segregation in aluminum alloy die castings
    Izumi MURASHIMA, Akira ISHIKAWA, Hideto SASAKI, Naomi NISHI
    1999 Volume 49 Issue 10 Pages 487-492
    Published: 1999
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.49.487
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The effects of casting conditions on segregation of solute elements at die castings surface were investigated and the formation mechanism of segregation at die castings surface is discussed using two kinds of alloys. JIS–ADCIO and Al–4.5 mass% Cu alloy have been cast by laminar flow die casting process. The segregation of solute elements at the surface of die castings were examined by SEM and EPMA technique. In the case of ADC 10, the concentration of Si, Cu, Fe and Mg segregated at die casting surface is more than two times in comparison with the average value of ADC 10 alloy die castings. The segregation of Cu, Fe and Mg increases with increasing casting pressure and decreasing casting temperature. And segregation of these elements decreases by decreasing shot velocity and intensified pressure time lag. However, segregation of Si is affected by only casting temperature and concentration of Si at die casting surface increased with increasing the casting temperature. It has been revealed that the segregation of Cu at the surface of Al–4.5 mass%Cu alloy die castings is affected with solidification ratio of the surface layer and timing of intensified pressure. The formation of surface segregation can be occurred by the squeeze out of interdendritic solute-enriched liquid into the gap between die casting and mold surface by intensified pressure.
    View full abstract
    Download PDF (1306K)
  • Plain fatigue and fretting fatigue strengths of AC4CH aluminum alloy
    Tomohisa NISHIDA, Junnosuke MIZUTANI, Yoshiharu MUTOH, Kenji YOSHII, O ...
    1999 Volume 49 Issue 10 Pages 493-498
    Published: 1999
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.49.493
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Plain fatigue, fatigue crack growth and fretting fatigue tests were carried out using cast Al–Si aluminum alloy JIS AC4CH–T6 as well as the forged aluminum alloy JIS 6061–T6. Plain fatigue strength of the cast aluminum alloy was lower than that of the forged alloy. The lower fatigue strength was attributed to casting defects such as pores in the cast aluminum alloy, which enhanced fatigue crack formation. On the other hand, fretting fatigue strength of the cast aluminum alloy was almost equal to that of the forged alloy. No difference of both tangential force coefficient in fretting fatigue and fatigue crack growth rates were observed between the two materials. The prediction of fretting fatigue lives for both materials were made on the basis of the fracture mechanics approach. The predicted lives were in good agreement with the experimental results.
    View full abstract
    Download PDF (972K)
  • Surface modification of 5083 aluminum alloys using friction surfacing
    Takeshi SHINODA, Jinqi LI
    1999 Volume 49 Issue 10 Pages 499-503
    Published: 1999
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.49.499
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Although the friction surfacing had been proposed and applied successfully in surface modification for various metals, the conventional friction surfacing process has some difficulties for applying aluminum alloy due to its specific physical characteristics, such as high thermal conductivity and relatively low strength comparing to steel materials. A novel process underwater friction surfacing has been proposed in this report to achieve stabilized friction surfacing process. Furthermore, an attempt had been made to deposit an aluminum alloy metal matrix composite (M.M.C.) coatings reinforced with alumina particles, onto a 5083 aluminum alloy plate by new process, in which a hollow rod of 5052 aluminum alloy was used with the hollow section filled with 5 μm diameter of alumina powders. The M.M.C. coatings had been achieved with uniformly distributed reinforcement particles up to 12% volume fraction.
    View full abstract
    Download PDF (1277K)
Errata
REVIEW—2nd JILM PRIZE & AWARDS
LECTURE
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top