Development of new high strength Al-Si eutectic alloys and investigation of their fatigue properties in extra-long life range.

新型高强度铝硅共晶合金的开发及其超长寿命范围内的疲劳性能研究。

• 批准号: 03555016
• 负责人: MURAKAMI Yukitaka
• 金额: $ 10.18万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research (B)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03555016/
• 关键词: 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; 投影面積の平方根√area; 引張強さ; 不均質相; 超高速疲労試験; 疲労限度の予測

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.

为寻求材料开发的最佳工艺条件，系统地研究了Al-Si共晶合金中Si相分布与力学性能的关系，并采用连铸和挤压两种工艺制备了拉伸试样，得到以下结果：（1）热处理影响基体硬度，但不改变Si相分布; (2)抗拉强度σ v与基体的维氏硬度H_v成正比。(3)最大Si相的尺寸（* 面积_<max>）对塑性σ_f的影响最为关键。为了研究Si相对Al-Si共晶合金在长疲劳寿命区（N*10^7）和超长疲劳寿命区（N&gt;10^8）疲劳性能的影响，进行了拉压疲劳试验。得到的结果是：（1）在挤压变形条件下，超长寿命的疲劳断裂机制为剪切型，与长寿命时断裂起源于Si相的疲劳断裂机制不同。(2)在连铸情况下，所有的疲劳断裂都是由剪切型裂纹引起的。(3)在挤压条件下，疲劳极限可用面积参数模型预测，即用<max>Si相的面积和H_v两个参数来预测。

项目成果

Yukitaka Murakami: "S-N curves and Microstructures of Al-Si Eutectic Alloys." The 71th JSME Annual Meeting. Vol.B. 168-170 (1993)

Yukitaka Murakami：“Al-Si 共晶合金的 S-N 曲线和微观结构。”

Yukitaka Murakami: "Influence of Si Phase on Mechanical Properties of Al-Si Eutectic Allyos." Asian Pacific Conference on Fracture and Strength '93.37-42. (1993)

Yukitaka Murakami：“硅相对铝硅共晶合金机械性能的影响”。

Yukitaka Murakami: "Evaluation of Effect of Si-Phase on Fatigue Strength of Al-Si Eutectic Alloys." Proceedings of the 1993 Annual Meeting of JSME/MMD. No.920-72. 91-92 (1993)

Yukitaka Murakami：“评估硅相对铝硅共晶合金疲劳强度的影响。”

村上敬宣: "Al-Si共晶合金のS-N曲線とミクロ組織" 日本機械学会第71期全国大会講演論文集. B. 168-170 (1993)

Takanobu Murakami：“Al-Si共晶合金的S-N曲线和微观结构”日本机械工程学会第71届全国会议论文集B.168-170（1993）。

Y.Murakami,T.Takafuji,H.Ikeda and E.M.Coudert: "Influence of Si Phase on Mechanical Properties of Al-Si Eutectic Alloys" Asian Pacific Conference on Fracture and Strength'93. (1993)

Y.Murakami、T.Takafuji、H.Ikeda 和 E.M.Coudert：“Si 相对 Al-Si 共晶合金机械性能的影响”亚太断裂与强度会议93。