Kozo Kishi1 and Hiroshi Eda1
1Department of Mechanical Engineering, Faculty of Engineering, Utsunomiya University, Utsunomiya
The cutting mechanism of aluminium-silicon alloys, in which hard grains (silicon) are included in soft matrix (aluminium), requires a very complicated analysis, because the deformation mechanisms of the two phases are quite different. Aluminium-silicon alloys used in this paper are typical examples of those alloys since aluminium deforms by ductility but silicon shows brittle deformation. Hyper-eutectic alloys offer the possibility of optimum wear resistance and expansion behavior but pose serious manufacturing difficulties. And those alloys have been said, however, to be difficult of precision machining. Furthermore, the built-up edges (BUE) is formed comparatively easy.
In this experiment, the formation of the built-up edges was investigated with reference to the 3.0∼30.0% silicon range and its heat treatment T5, T6.
(1) The size of BUE became smaller with an increase in the silicon content. And the existence of BUE was seldom observed at above 22.0%Si content.
(2) The massive primary silicon was cut by BUE in most cases.
(3) The BUE formed by use of a diamond tool was scarcely observed in the range 3.0∼30.0%Si content.
(4) The primary silicon in the BUE was made finer than the original form, and the coarsened primary silicons ars seldom observed.
(5) The increase of the Al, Cu, Mg, Ni contents in the BUE was seldom observed as compared with the matrix, but the primary silicon increased to a certain degree.
(6) At about 8.0∼11.7%Si content where BUE become largest, the stress σn determined by the visioplasticity method is tensile stress in the neighborhood of the tool edge.
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