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Volume 33, Issue 8
Displaying 1-8 of 8 articles from this issue
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Yasuhisa TOZAWA1983 Volume 33 Issue 8 Pages 443-444
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (324K) -
Yoshiei SHINADA, Yoshisada UEDA, Seiki NISHI1983 Volume 33 Issue 8 Pages 445-451
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSMolten aluminum in which excess hydrogen I.3 to I.5 cc/Ioo g had dissolved was solidified unidirectionally and water quenched in the course of solidification. A (liquid + hydrogen pore) region is formed in the liquid ahead of the solid-liquid interface. Pores are formed before end of solidification. Pores in the region are coarse near the interface and become finer with distance from the interface. A coarse and elongated pore near the interface is that incorporated with two or three pores. Pores are formed on oxides or inclusions in the melt and trapped by the advancing interface before floating away. The trapped pores incorporate with pores in the region ahead of the interface and grow into elongated cylindrical ones. Molecular hydrogen is condensed at the interface, while atomic hydrogen in solution shows a contrary tendency.View full abstractDownload PDF (1912K) -
Kunio NAITO, Takatoshi SUZUKI, Motoyuki NAKAMURA1983 Volume 33 Issue 8 Pages 452-456
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSIncrease in torque and creaky noise often encountered in drilling hyereutectic Al-Si alloys were studied in various drilling conditions. The torque increase and creaky noise are caused by burnishing of a drill margin and a hole wall. Cyclic fluctuation of torque exactly corresponds to the profile of a hole with poor roundness. The burnishing easily occurs at a low built-up edge and under considerable drill wear. A built-up edge is formed in drilling on the margin face resulting in enlarging the effective drill diameter and preventing the burnishing. Recession of a cutting edge by wear accelerates burnishing because of an increase in margin contact with a hole wall. Hypereutectic Al-Si alloys particularly T6 treated permit a low built-up edge and considerable drill wear.View full abstractDownload PDF (605K) -
Ken TOHMA, Yo TAKEUCHI1983 Volume 33 Issue 8 Pages 457-465
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSElectrochemical characteristics of aluminum alloys in acidified chloride solutions were investigated to discuss the validity of CASS test for evaluating atmospheric corrosion resistance. A pitting corrosion resistant Al-Mg-Zn alloy is corroded in the general manner at the beginning of CASS test and in the manner similar as that of usual alloys after prolonged time. Both anodic and cathodic polarizations slightly occur near the corrosion potential. The latter does further slightly with the immersing time in the solution containing Cu++ ions or with the amount of Cu deposited on the specimen surface. An accelerating effect of Cu mainly functions on less noble ones in galvanic corrosion of aluminum alloys with Cu, and corrosion of noble ones considerably moderated. These facts show that Cu++ ions have a potential effect on accelerating pitting corrosion and the sacrificial anode effect of less noble alloys is exhibited adequately in CASS test. CASS test is an evaluating method not so suitable for corrosion resistance in moderate atmospheric environments.View full abstractDownload PDF (2951K) -
Michio NANJO, Koji MIMURA1983 Volume 33 Issue 8 Pages 466-473
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDemagging was tried using ZnCl2 dissolved in NaCl-KCl eutectic salt bath as a substitute for expensive AlCl3 and AlF3. The demagging reaction is:
Mg (in Al) + ZnCl2→Zn (in Al) + MgCl2
The products are Zn-Al alloy and MgCl2 entrapped in NaCl-KCl melt. Separation of Zn and Al and electrolysis of MgCl2 in NaCl-KCl melt are required to extract Zn, Al, Mg and Cl2 gas. This substitutional chlorination reaction results in complete transfer of Mg from Al scrap to salt bath without loss ofAl or without harmful AlCl3 and Cl2 gases emission and MgCl2 wast generation. The demagging with ZnCl2 is controlled by complex ion formation among weak Lewis base ZnCl2 and strong base AlCl3 and MgCl2. An addition of NaCl-KCl to ZnCl2 as a reaction medium overcomes depression of ZnCl2 activity and dilutes Mg in Zn-Al alloy down to 0.01wt% at 650°C quickly.View full abstractDownload PDF (1057K) -
Koichi UESAKI, Takashi KAWAKAMI, Hideo TAKECHI1983 Volume 33 Issue 8 Pages 474-481
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSCommercial Al-Zn-Mg alloys T6 treated and welded were tested in 5.0%NaCl +0.3%H2O2 aqueous solution. The welded alloy fractures in tensile testing at weld metals and does in SCC testing in the heat affected zone. SCC fracture occurs at a greater distance from the fusion boundary, in a shorter time and in the more typical intergranular manner, as the postweld time is prolonged. The microstructural change in accordance with postweld aging has a significant effect on SCC. Anodic dissolution of grain boundary precipitates plays an important role in SCC.View full abstractDownload PDF (2023K) -
Toshio ENJO1983 Volume 33 Issue 8 Pages 482-490
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
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Shiro KOHARA1983 Volume 33 Issue 8 Pages 491-499
Published: August 31, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (1469K)
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