尺寸效應對材料硬度與界面摩擦之影響

The Influences of Size Effects on Material Hardness and Interface Friction

蔡嘉文(Chia-Wen Tsai)

指導教授 ： 陳復國

國立臺灣大學/工學院/機械工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01413

摘要

精微成形是目前我國工業發展上的重要技術，當成品尺寸縮小時，因為尺寸效應將使材料機械性質與摩擦特性和傳統上的表現不同。釵h在傳統工業發展時可忽略之特性，在精微尺寸下其影響將變大。然而在材料縮小時，在材料特性量測上的難度將逐漸增加。另外，在傳統塑性力學中，可以發現硬度和流應力具有特定比例關係。本文將利用相似原理的方式進行實驗設計，使用電子零件製作上常用之銅材，先是透過不同尺寸大小的圓柱壓縮實驗，以及微硬度的使用，觀察尺寸效應對壓縮流應力與材料硬度之影響，以及觀察是否可以由硬度反推應力應變曲線，輔助量測微小尺寸試片之應力應變線。除此之外，將利用一前後擠出之實驗，對於銅材之摩擦性質與成形性，隨著晶粒大小與模具尺寸的改變，將產生何種影響。並和過去所進行的實驗相對照，以進行結果的探討。

關鍵字

精微成形 ； 應力應變曲線 ； 錐杯擠形 ； 微硬度 ； 有限元素法

並列摘要

Microforming is an important technology in the development of industry. When the product is getting smaller, the so-called size-effect makes the material properties changes and the friction characteristics different with it in convenient works. A lot of properties we neglect in convenient working will become effective in microforming process. However, the smaller the material is, the harder in measuring the mechanic properties. Besides, we can know that the hardness has some specific relations with the flow stress. The present study uses the theory of similarity to design experiences. Observe the compression stress in different scale material and use microhardness to analyze the effect in flow stress and hardness by size-effect. Trying to find the hardness-strain curve and compare with the stress-strain curve. Analyze the applicability of adjusting the measuring of stress-strain curve in small materials by hardness test. Finally, analyze the lubrication properties and formability change with the size of grain and die using a forward-backward extrusion process.

並列關鍵字

microforming ； stress-strain curve ； micro-indentati

參考文獻

3. T.A. Kals, and R. Eckstein, “Miniaturization in Sheet Metal Working”, Journal of Materials Processing Technology, vol.103, (2000), pp. 95-101.

4. M. M. Chaudhri, “Subsurface Strain Distribution around Vickers Hardness Indentation in Annealed Polycrystalline Copper”, Acta mater. , vol. 46, No.9, (1998), pp.3047-3056.

5. X. Yao, S. Zajac, and B. Hutchinson, “Estimation of Compression Flow Stress from Post-deformation Hardness in Al-Mg Alloys”, Scripta Materialia, vol.41, No.3, (1999), pp.253-258.

6. J.H. Ahn, and E.C. Jeon, Y. Choi, Y.H. Lee, D. Kwon, “Derivation of Tensile Flow Properties of Thin Films Using Nanoidentation Technique”, Current Applied Physics 2, (2002), pp.525-531

8. A. Buschhausen, K. Weinmann, J.Y. Lee, and T. Altan, ”Evaluation of Lubrication and Friction in Cold Forging Using a Double Backward-Extrusion Processing”, Journal of Materials Processing Technology, 33, (1992), 95-108