1993 Fiscal Year Final Research Report Summary
Development of new high strength Al-Si eutectic alloys and investigation of their fatigue properties in extra-long life range.
| Project/Area Number |
03555016
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械材料工学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
MURAKAMI Yukitaka Kyushu Univ., Mech. Engng., Professor., 工学部, 教授 (10038010)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Toshimasa KOBE STEEL LTD., Al Research Div., Senior Researcher., 軽合金伸銅事業部, 主任研究員
YANAGIMOTO Shigeru SHOTIC CORPORATION, Technical Div., Chief Manager., 副主幹
KITAGAWA Eiji TOYADA AUTOMATIC LOOM WORKS, LTD., Engng., Researcher., コンプレッサ事業部, 研究員
IKEDA Hayato TOYADA AUTOMATIC LOOM WORKS, LTD., Engng., Group Leader., コンプレッサ事業部, 課長
TORIYAMA Toshiyuki Kyushu Univ., Mech. Engng., Research Associate., 工学部, 助手 (30227681)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Fatigue / Extra-long life fatigue / Al-Si eutectic alloy / *area_<max> of Si-phase / Vichers hardness / Ultimate tensile strength / Shear type crack / Tension-compression fatigue |
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| Research Abstract |
To find the optimum conditions for the material development, the relationship between Si-phase distribution and mechanical properties of Al-Si eutectic alloys in terms of production factors was systematically investigated.
Tensile test specimens were prepared from two materials produced by two different processes, continuous casting and extrusion.
The obtaind results are : (1) Heat treatment influences the matrix hardness without changing Si-phase distribution. (2) Ultimate tensile strength siguma v is proportional to Vickers hardness H_v of Al matrix. (3) The size(*area_<max>) of the maximum Si-phase has a most crucial effect on ductility epsilon_f.
In the next step, to investigate the effect of Si-phase on fatigue properties of Al-Si eutectic alloys in long fatigue life range (N*10^7) and extra-long fatigue life range (N>10^8), tension-compression fatigue tests were carried out. The obtained results are : (1) In the case of extrusion, the fatigue fracture mechanism in extra-long life was shear type and different from that in long life in which the fracture origin was at Si-phase. (2) In the case of continuous casting, all the fatigue fractures were caused by shear type cracking.
(3) In the case of extrusion, the fatigue limit can be predicted by the *area parameter model, i.e. with two parameters, the *area_<max> of Si-phase and H_v.
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