All issues
Volume 50, Issue 1
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
RESEARCH REPORT
-
Toshihiko KUWABARA, Keiichi KURITA2000 Volume 50 Issue 1 Pages 2-6
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSBiaxial tensile tests of 6000–type sheet aluminum alloy were carried out using newly designed cruciform specimens. The specimens were deformed under linear loading paths in a servo-controlled biaxial tensile testing machine. Plastic orthotropy remained coaxial with the principal stresses throughout every experiment. On the other hand, the successive contours of equal plastic work in biaxial stress space changed their shapes progressively, exemplifying differential work hardening. The geometry of the entire family of the work contours was compared with the yield loci calculated from existing yield criteria. The work contour at 0.0005 equivalent plastic strain almost coincided with the von Mises ellipse, while its curvature decreased as work-hardening progressed and became close to the Tresca-type yield locus. Moreover, it was observed that the directions of the measured plastic strain vectors were almost coincided with the associated normals to the current work contour in stress space; accordingly it appears that the work contours act as instantaneous plastic potentials at least under linear loading paths. The effect of age-hardening on the geometry of work contours was small.View full abstractDownload PDF (421K) -
Yuuji ABE, Masakatu YOSHIDA, Tutomu TAGATA, Mamoru MATUO, Takao KAWANA ...2000 Volume 50 Issue 1 Pages 7-11
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSIn this study, warm forming die and blank holder could be heated and punch could be cooled always. At first, relation between die profile radius and drawing ratio was experimented in cylindrical cup drawing. Next, oil pan that is one of difficult part to press forming at room temperature was experimented and foreword experimental result was applied to die profile radius of oil pan. At last, warm forming of oil pan was continually examined. The results were following, (1) LDR of cylindrical cup drawing of warm forming were great than that of room temperature forming, but showed a violent variation with die profile radius, and fractures were in cup wall near to die profile. (2) An indication of good performance of warm forming was given with oil pan 1 stroke press, so oil pan from aluminum alloy sheets by warm forming had no fracture, but that by room temperature forming had fracture and that from steel sheets too. (3) Warm forming of oil pan from aluminum alloy sheets could be continued without break and mass productivity should be improve with insulation of handling machines.View full abstractDownload PDF (549K) -
Norihito KIMURA, Junichi KANEKO, Makoto SUGAMATA2000 Volume 50 Issue 1 Pages 12-17
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSIn order to assess the optimum alloying composition, rapidly solidified P/M materials were prepared for Al–Mn–Cr ternary alloys containing 6∼8 mass%Mn and 1∼3 mass%Cr. Effects of alloying composition on precipitation hardening were studied with a purpose of obtaining precipitation-hardened materials with some acceptable ductility. The critical composition to observe precipitation hardening was identified as 8.8 mass%Mn + Cr, above which hardening increased with increasing Mn + Cr. The largest hardening was observed for 7Mn–3Cr alloy containing highest Mn + Cr. CrAl7 was formed in as rapidly solidified state, and precipitation of MnAl6 occurred during hot extrusion in alloys of lower Cr content. Finally, G phase, (Mn, Cr) Al12 was formed during heating of hot-extruded materials, thereby hardening occurred when amount of G phase formation is sufficiently large. For the as-extruded P/M materials, the highest tensile strength of 480 MPa was obtained at room temperature for 7Mn–3Cr with 7% elongation. Elongation of the as-extruded P/M materials kept unchanged up to 473 K but increased appreciably at 673 K. However, the heat-treated P/M materials showed poor ductility and hence tensile strength decreased with aging time regardless of occurrence of hardening. Increases in elastic modulus were observed after precipitation heat treatment.View full abstractDownload PDF (676K) -
Nobuhiro KOGA2000 Volume 50 Issue 1 Pages 18-22
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSRecently, the demand for magnesium alloy formed by thixomolding for use in home electric appliances and automobile parts has been rapidly growing, because of the need to reduce their weight and improve the heat radiation, electromagnetic shielding and recycling performances. In this study, I examined the possibility of press-piercing of a thixomolding-processed MD1D magnesium alloy sheet, which is believed to be difficult due to its low-ductility material, and also examined the appropriate processing conditions, by experiments. Results revealed that a pierced surface devoid of defects such as cracks is consistently obtained when the clearance between the punch and die is set at 10%t or smaller in the press-piercing of a magnesium alloy sheet. Furthermore, from the results it was also clarified that piercing of a magnesium alloy sheet by the cut-off punching process, in which piercing and shaving are performed within 1 stroke of the press machine, provides a highly accurate hole in the entirely smooth shaved surface.View full abstractDownload PDF (527K)
REVIEW
-
Kenji MATSUDA, Susumu IKENO2000 Volume 50 Issue 1 Pages 23-36
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSDownload PDF (1874K)
LECTURE
-
Hidetoshi Kawada2000 Volume 50 Issue 1 Pages 37-42
Published: January 30, 2000
Released on J-STAGE: June 30, 2021
JOURNAL FREE ACCESSDownload PDF (6264K)
- |<
- <
- 1
- >
- >|