锻压技术

等径角挤压Al-3%Si合金裂纹的萌生及扩展

英文标题：Formation and growth of cracks in Al-3%Si alloy during ECAP

作者：丁雨田李海龙郭廷彪胡勇刘博

单位：兰州理工大学

关键词：等径角挤压脆硬相应力集中裂纹

分类号：

出版年,卷(期):页码：2014,39(10):132-134

摘要：

使用内角为105°和外角为37°的模具对Al-3%Si合金进行了A路径等径角挤压实验，采用光学显微镜和扫描电镜观察了试样裂纹的萌生和扩展，结果表明，Al-3%Si合金在A路径经过3道次挤压后，观察到材料上表面（与模具内角接触的表面）有裂纹出现，随着挤压道次的增加，应变累积量不断积累，裂纹由浅到深，由小到大发生变化。分析认为：材料在ECAP变形过程中材料上表面变形剧烈，随着挤压道次的增加，脆硬相共晶Si发生碎断，碎断后的共晶Si偏离基体ɑ-Al并伴随凹坑出现，脆硬相共晶Si和空穴处产生应力集中导致裂纹萌生；裂纹在表面拉应力和剪切力的作用下进行扩展。

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.

基金项目：

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

参考文献：

[1]Valiev R Z,Krasilnikov N A,Tsenev N K.Plastic deformation of alloys with sbmicron grained structure[J]. Materials Science & EngineeringA, 1991, 137(15) : 35-40.

[2]Zhu Y T, Lowe T C. Observations and issues on mechanisms of grain refinement during ECAP process[J]. Materials Science and Engineering: A, 2000, 291(1): 46-53.

[3]刘晓燕, 赵西成, 杨西荣, 等. ECAP 变形制备超细晶金属材料变形行为的研究进展[J]. 材料导报, 2011, 25(9): 11-15.

Liu X Y，Zhao X C，Yang X R，et al.Progress in research on deformation behavior of ultrafine-grained metallials processed by ECAP[J]. Materials Review A: Review Articles, 2011,25（5）：11-15.

[4]Suh J Y. Effect of deformation histories on texture evolution during equal- and dissimilar-channel angular pressing[J]. Scripta Materialia, 2003, 49: 185-190.

[5]Kappor R, Li Y J, Wang J T, et al. Creep transients during stress changes in ultrafine-grained copper[J]. Scripta Materialia, 2006, 54: 1803-1807.

[6]何运斌, 潘清林, 刘晓艳, 等. 镁合金等通道转角挤压过程中的晶粒细化机制[J]. 中国有色金属学报, 2011, 21(8): 1785-1793.

He Y B，Pan Q L，Liu X Y，et al. Grain refinement mechanism of magnesium alloy during equal channel angular pressing process[J]. The Chinese Journal of Nonferrous Metals,2011,21(8）：1786-1792.

[7]毕见强,孙康宁,尹衍升,等.等径角挤压Al4.25%Cu 多晶材料的裂纹产生与扩展[J]. 人工晶体学报, 2006, 35(4): 724-727.

Bi J Q，Sun K N，Yin Y S，et al.Fomation and growth of Al-4.25%Cu alloy pressed by ECAP[J]. Journal of Synthetic Crystals,2006,35(4):724-727.

[8]陈文杰,周清,邓竹君,等.基于NormalizedC&L准则的ECAP裂萌生趋势的数值模拟[J].锻压技术，2010,35（5）：160-162.

Chen W J, Zhou Q, Deng Z J, et al.Numerical simulation of crack initiation trends during ECAP based on Normalized Cockcroft & Latham ductile fracture criterion[J].Forging & Stamping Technology, 2010,35（5）：160-162.

[9]齐广霞, 徐培培, 史丽坤. GH4169 高温合金叶片挤压制坯成形规律研究[J]. 锻压技术, 2013, 38(1): 168-171.

Qi G X，Xu P P，Shi L K.Research on laws of extrusion blank forming for GH4169 superally blade[J].Forging ＆ Stamping Technology, 2013, 38(1): 168-171.

[10]岳珠峰.多晶体光滑表面疲劳微裂纹形核机理研究[J].应用数学和力学,2004,25（8）：810-812.

Yue Z F. On the study of the initiation of the micro crack on the smooth surface of polycrystalline[J].Applied Mathematics and Mechanics, 2004,25（8）：810-812.

[11]崔忠圻,谭耀春.金属学与热处理[M].2版.北京：机械工业出版社，2007.

Cui Z Q,Tan Y C.Metal Science and Heat Treatment [M]. The Second Edition.Beijing:China Machine Press, 2007.

服务与反馈：

【文章下载】【加入收藏】