Study on Fatigue Properties of Al-Mg Alloy Produced by Severe Plastic Deformation by means of In-Situ SEM Observation

原位SEM观察强塑性变形铝镁合金疲劳性能研究

• 批准号: 10650690
• 负责人: KITAGAWA Kazuo
• 金额: $ 2.43万
• 依托单位: KANAZAWA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650690/
• 关键词: fine grain; ECAE; A5056 alloy; low cycle fatigue; high cycle fatigue; fatigue crack; ECAP; 5056Al合金; 疲労特性; き裂伝ぱ特性; 超微結晶

There have only been a limited number of studies on the fatigue behavior of ultra-fine grained materials with nano- or sub-microcrystalline structure and no reports are available on the fatigue of Equal-Channel Angular Extrusion (ECAE) Al-alloys. The purpose of the present work is to explore cyclic properties of 5056 Al-alloy after ECAE treatment and to get a better insight on general fatigue and tensile performance of materials with fine-grain metastable structures produced by severe deformation. Since the influence of technological parameters on the resultant ECAE structure and properties has not been fully understood yet and is currently being extensively investigated, we do not believe that the results presented here are the best obtainable with the ECAE technology on the Al-alloys. We attempt to clarify both the benefit and draw back of ECAE for fatigue Properties to provide a guideline for further development of this process towards enhancement of practical characteristics of mat … More erials.Mechanical properties and fatigue performance of 5056 A1-Mg alloy fabricated by the ECAE are assessed in tensile and cyclic experiments in terms of yield stress, ultimate tensile strength, elongation, fatigue limit, S-N curve and fatigue growth rate.1) The modest enhancement of fatigue performance is achieved in the high stress regime in the fine-grain 5056 A1-Mg alloy if compared with the conventional O-temper material having a relatively large grain size. This advantage is, however, to a large extent discredited by a higher crack growth rate at low and intermediate stresses, lower apparent fatigue threshold and lower thermal stability of the severely predeformed alloy.2) The ECAE technique, in its form Used for the present work, does not reveal a distinct advantage for high-cyclic fatigue when compared with standard processing. Although this result may look discouraging, there is an obvious enhancement of the fatigue life in the low cyclic regime and of the crack growth rate at large stress intensity factor range. Additionally we have to bear in mind that the flexibility to vary many parameters during equal-channel pressing provides perspective possibilities for microstructure control and, therefore, for materials design. Further development of ECAE processing is necessary to improve fatigue and/or tensile performance of ECAE Al-alloys. Less

目前对纳米或亚微晶结构超细晶材料疲劳行为的研究还很有限，而对双通道角挤压（ECAE）铝合金疲劳行为的研究还未见报道。本工作的目的是探索ECAE处理后的5056铝合金的循环性能，并得到一个更好的洞察一般的疲劳和拉伸性能的细晶亚稳态组织的材料产生严重的变形。由于工艺参数对所得ECAE结构和性能的影响尚未完全了解，目前正在进行广泛的研究，我们不认为这里给出的结果是铝合金ECAE技术的最佳结果。我们试图阐明ECAE对疲劳性能的好处和缺点，为进一步发展这一工艺以提高板坯的实用性能提供指导 ...更多信息 在拉伸和循环试验中，根据屈服应力、极限抗拉强度、伸长率、疲劳极限，1）细晶5056 A1-Mg合金在高应力区的疲劳性能比常规的O-Mg合金略有提高。回火具有相对大晶粒尺寸材料。然而，这一优势在很大程度上被低应力和中等应力下较高的裂纹扩展速率、较低的表观疲劳阈值和严重预变形合金的较低的热稳定性所怀疑。2）与标准加工相比，用于本工作的ECAE技术在高循环疲劳方面没有显示出明显的优势。虽然这一结果可能看起来令人沮丧，有一个明显的提高疲劳寿命在低循环制度和裂纹扩展速率在大的应力强度因子范围。此外，我们必须记住，在等通道挤压过程中改变许多参数的灵活性为微观结构控制和材料设计提供了可能性。为了提高ECAE铝合金的疲劳和/或拉伸性能，有必要进一步发展ECAE工艺。少

项目成果

Kitagawa K.: "On the Cyclic Behaviour of Ultra-Fine Grained Copper Produced by Equi-Channel Angular Pressing" Proceeding of IS MANAM'98(Australia). (印刷中).

Kitakawa K.：“关于等通道角压制生产的超细晶粒铜的循环行为”IS MANAM98 论文集（澳大利亚）（正在出版）。

Y. Kaneko: "Hysteresis Loop Shape of a Cyclically-Deformed Copper Tricrystal Having Two Longitudinal Grain Boundaries"Scripta Materialia. 38. 1609-1614 (1998)

Y. Kaneko：“具有两个纵向晶界的循环变形铜三晶的磁滞回线形状”Scripta Materialia。

A. Vinogradov: "Fatigue Properties of 5056 Al-Mg Alloy Produced by Equal-Channel Angular Extrusion"J. of Nanostructured Material. 印刷中.

A. Vinogradov：“等通道角挤压生产的 5056 铝镁合金的疲劳性能”，《纳米结构材料》杂志。

Y. Kaneko: "Fatigue Crack Propagation in Copper Bicrystals Having the Grain Boundaries of Σ3 Vicinical Domain"Proc. Interface Science (Paris). (1998)

Y. Kaneko：“具有 Σ3 邻域晶界的铜双晶中的疲劳裂纹扩展”Proc。界面科学（1998 年）。

Y. Kaneko: "Faigue Crack Propagation in Single Crystal-and Bicrystals of a Ferritic Stainless Steel"Proc. FATIGUE'99 (Beijing). (1999)

Y. Kaneko：“铁素体不锈钢单晶和双晶中的疲劳裂纹扩展”Proc。