Transactions of Materials and Heat Treatment

Title：Formation and growth of cracks in Al-3%Si alloy during ECAP

Authors： Ding Yutian1 2 Li Hailong Guo Tingbiao Hu Yong Liu Bo

Unit： Lanzhou University of Technology

KeyWords： ECAP hard brittle phase stress concentration crack

ClassificationCode：

year,vol(issue):pagenumber：2014,39(10):132-134

Abstract：

Based on Al-3%Si alloy, the ECAP test through route A was carried out by die with inner angle 105° and outer angle 37° and the formation and growth of crack were observed by OM and SEM. The results show that there are cracks on the upper surface of the sample (surface contacting with the inside corner of die) after three-pass extrusions in route A for Al-3% alloy. With the increasing of extrusion passes, the amount of the strain accumulation increases gradually, so the crack is changed from shallow to deep and small to big. Analysis shows that the intense deformation is produced on the upper surface during ECAP process, and with the increasing of extrusion passes, the hard brittle phase eutectic Si is chopped and deviated from matrix ɑ-Al with pits appearance. Crack formation is caused by stress concentration produced in brittle eutectic Si and holes，and the crack expands under tensile stress and shear force of the surface.

Funds：

国家自然科学基金资助项目（51261016）；甘肃省高等学校基本科研业务费（1201ZTC056）

丁雨田(1962-)，男，博士，教授

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