ECAP变形对AZ91镁屑固相成形材料显微组织与力学性能的影响
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摘要
本文采用冷压-热压-热挤压和冷压-热压两种方法对AZ91镁合金车削屑进行了固相成型,并在300℃、350℃对其进行了1~4道次的ECAP变形。采用光学显微镜研究了AZ91镁屑固相成型材料ECAP变形前后的显微组织变化,采用X射线衍射对ECAP变形前后AZ91镁屑固相成型材料的织构演变进行了分析,采用拉伸试验机对ECAP变形前后AZ91镁屑固相成型材料的室温拉伸及压缩性能进行了测试,采用阿基米德法对ECAP变形前后AZ91镁屑固相成型材料的密度进行了测试。
铸态和固溶态AZ91镁屑经冷压-热压后密度较小,屑与屑之间的结合并不十分紧密,还有观察到屑与屑之间的界面以及孔洞等缺陷的存在;热挤压后密度急剧增加,基本达到饱和。热挤压后晶粒度约为10μm,经过300℃1~2道次的ECAP,晶粒尺寸可以达到2~3μm。随着ECAP变形道次的增加,较大晶粒逐渐破碎,再结晶大面积发生,晶粒分布趋于均匀。随着变形温度的升高,再结晶越来越充分,晶粒逐渐趋于等轴,位错密度逐步降低。由于受到晶粒度和织构双重因素的影响,ECAP变形后AZ91镁屑固相成型材料的屈服强度随着变形道次和变形温度的升高逐渐降低,延伸率也逐步降低,这可能是由于氧化物的存在,诱发孔洞的产生,导致延伸率的下降。经过300℃1道次的ECAP,材料的屈服强度和抗拉强度相比挤压态提高了40%和25%。
铸态AZ91镁屑冷压-热压后直接进行ECAP变形,材料的密度提升没有热挤压来的快,ECAP变形4道次后,材料的密度基本达到饱和。经过1~2道次的ECAP,晶粒尺寸可以达到4μm。随着变形道次的增加,较大晶粒逐渐破碎,再结晶大面积发生,晶粒分布趋于均匀,经过4道次的ECAP变形,晶粒尺寸细化到2μm。材料的屈服强度随着随着变形道次的增加先升后降,这是由于晶粒度和织构之间的竞争作用及致密度的影响。材料的抗压强度及延伸率随着道次的增加而增加,这主要是由于密度及晶粒度的影响。
Two ways were used to recycle AZ91 magnesium chips in this paper. One was solid state recycling by hot extrusion and ECAP, the other is directly ECAP without hot extrusion. Equal channel angular pressing (ECAP) was performed at the temperature 300℃and 350℃for different passes. The microstructure of the ECAPed AZ91 chips were examined by means of optical microscopy (OM). Texture development of the as-extruded and ECAPed AZ91 magnesium chips were investigated by X-ray diffractometer. Tensile deformation behavior of the as-extruded and ECAPed AZ91 magnesium chips at room temperature were investigated. The densities of as-extruded and ECAPed AZ91 chips were measured by Achemide method
Two kinds of AZ91 magnesium chips(As-cast and T4) were selected as the material for solid state recycling by hot extrusion and ECAP. After cold-press and hot-press, the density was low, this was due to the weakness of the bond between chips, but after hot extrusion, the density increased dramatically, almost achieved full density. The as-extruded chips had an initial grain size of about 10μm, after 1~2 passes of ECAP at 300℃, the grain size was refined to 2~3um. With the increase of ECAP pass, the grain sizes became more uniform.became equiaxed and dislocation density decreased. With the increase of ECAP temperature, the grains became more equiaxed and dislocation density decreased. Influenced by dual factors of grain size and texture, the yield stress of ECAPed AZ91 chips decreased with increasing of ECAP passes, and the ductility at ambient temperature was decreased because of cavitation induced by oxide from the surface of the chips. After 1 pass of ECAP at 300℃, the specimen showed about 40% higher 0.2% yield stress and about 25% higher tensile strength compared with as-extruded chips.
Another way of recycling without hot extrusion was conducted on as–cast magnesium alloy chips. After ECAP, the density was increased, but not as significant as hot extrusion. After 4 passes of ECAP, full density was achieved. The grains refined to 4um and 2um after 2 passes and 4 passes respectively. The yield stress of ECAPed AZ91 chips first increased and then decreased with increasing of ECAP passes, this was due to the density and dual factors of grain size and texture. The compression strength and elongation to failure were both increased with the increase of passes, the increase of density and fine grain size maybe the reason.
铸态和固溶态AZ91镁屑经冷压-热压后密度较小,屑与屑之间的结合并不十分紧密,还有观察到屑与屑之间的界面以及孔洞等缺陷的存在;热挤压后密度急剧增加,基本达到饱和。热挤压后晶粒度约为10μm,经过300℃1~2道次的ECAP,晶粒尺寸可以达到2~3μm。随着ECAP变形道次的增加,较大晶粒逐渐破碎,再结晶大面积发生,晶粒分布趋于均匀。随着变形温度的升高,再结晶越来越充分,晶粒逐渐趋于等轴,位错密度逐步降低。由于受到晶粒度和织构双重因素的影响,ECAP变形后AZ91镁屑固相成型材料的屈服强度随着变形道次和变形温度的升高逐渐降低,延伸率也逐步降低,这可能是由于氧化物的存在,诱发孔洞的产生,导致延伸率的下降。经过300℃1道次的ECAP,材料的屈服强度和抗拉强度相比挤压态提高了40%和25%。
铸态AZ91镁屑冷压-热压后直接进行ECAP变形,材料的密度提升没有热挤压来的快,ECAP变形4道次后,材料的密度基本达到饱和。经过1~2道次的ECAP,晶粒尺寸可以达到4μm。随着变形道次的增加,较大晶粒逐渐破碎,再结晶大面积发生,晶粒分布趋于均匀,经过4道次的ECAP变形,晶粒尺寸细化到2μm。材料的屈服强度随着随着变形道次的增加先升后降,这是由于晶粒度和织构之间的竞争作用及致密度的影响。材料的抗压强度及延伸率随着道次的增加而增加,这主要是由于密度及晶粒度的影响。
Two ways were used to recycle AZ91 magnesium chips in this paper. One was solid state recycling by hot extrusion and ECAP, the other is directly ECAP without hot extrusion. Equal channel angular pressing (ECAP) was performed at the temperature 300℃and 350℃for different passes. The microstructure of the ECAPed AZ91 chips were examined by means of optical microscopy (OM). Texture development of the as-extruded and ECAPed AZ91 magnesium chips were investigated by X-ray diffractometer. Tensile deformation behavior of the as-extruded and ECAPed AZ91 magnesium chips at room temperature were investigated. The densities of as-extruded and ECAPed AZ91 chips were measured by Achemide method
Two kinds of AZ91 magnesium chips(As-cast and T4) were selected as the material for solid state recycling by hot extrusion and ECAP. After cold-press and hot-press, the density was low, this was due to the weakness of the bond between chips, but after hot extrusion, the density increased dramatically, almost achieved full density. The as-extruded chips had an initial grain size of about 10μm, after 1~2 passes of ECAP at 300℃, the grain size was refined to 2~3um. With the increase of ECAP pass, the grain sizes became more uniform.became equiaxed and dislocation density decreased. With the increase of ECAP temperature, the grains became more equiaxed and dislocation density decreased. Influenced by dual factors of grain size and texture, the yield stress of ECAPed AZ91 chips decreased with increasing of ECAP passes, and the ductility at ambient temperature was decreased because of cavitation induced by oxide from the surface of the chips. After 1 pass of ECAP at 300℃, the specimen showed about 40% higher 0.2% yield stress and about 25% higher tensile strength compared with as-extruded chips.
Another way of recycling without hot extrusion was conducted on as–cast magnesium alloy chips. After ECAP, the density was increased, but not as significant as hot extrusion. After 4 passes of ECAP, full density was achieved. The grains refined to 4um and 2um after 2 passes and 4 passes respectively. The yield stress of ECAPed AZ91 chips first increased and then decreased with increasing of ECAP passes, this was due to the density and dual factors of grain size and texture. The compression strength and elongation to failure were both increased with the increase of passes, the increase of density and fine grain size maybe the reason.
引文
1尹从娟,张星,张治民.热挤压工艺对AZ31镁合金组织性能的影响.热加工工艺. 2007, 36(21): 63-67
2胡茂良.固相合成AZ91D镁合金组织结构及性能研究.哈尔滨理工大学工学博士学位论文. 2008:1-20
3石凤健,汪建敏,许晓静.等截面角形挤压的研究内容及现状.热加工工艺. 2003, 1: 51-53
4 I. Sabirov, O. Kolednik, R.Z. Valiev, R. Pippan. Equal Channel Angular Pressing of Metal Matrix Composites: Effect on Particle Distribution and Fracture Toughness. Acta. Mater. 2005, 53(18): 4919-4930
5祁庆据,刘勇兵,杨晓红.镁合金的研究及其在汽车工业中的应用与展望.汽车工程. 2002, 24(2): 94-100
6凌人蛟.镁合金变形细化晶粒的研究现状.航天制造技术. 2007,5:28-31
7钟皓,陈琪,闫蕴琪,张慧,翁文凭. AZ31镁合金的热挤压组织与力学性能分析.轻金属. 2007, 3: 52-55
8张济洲.镁合金成型加工工艺关键措施探研.平顶山工学院学报. 2003, 12(4): 29-33
9马存真.镁及镁合金废料国际标准提案介绍及我国镁废料现状.世界有色金属. 2002, 6: 71-73
10王祝堂.今后10年镁屑增长率可达9.5%.轻合金加工技术. 2001, 29(3):17
11陈刚,范培耕,彭晓东,曹鹏军.镁合金废料回收与再生技术研究现状.兵器材料科学与工程. 2007, 30(5): 73-76
12王云,陈敏强,杨利坚,龙思远.镁合金废料的回收.铸造技术. 2007, 128: 27-32
13张泷,唐靖林,曾大本.镁合金废料再生技术现状及发展趋势.锻造. 2006, 55: 221-223
14李明照,马非.镁合金废料的回收与利用.华北工学院学报. 2005, 26(2):153-156
15孟若愚,张代东,原洪加.镁合金成型技术研究进展.金属铸锻焊技术. 2008, 37(7): 89-93
16陈晓瑜,吉泽升,胡茂良.镁合金固相合成和回收的研究进展.轻合金加工技术. 2007, 35(4): 10-13
17 K. Katsuyoshi, T. Ritsuko, W.B. Du. Manufacturing High Property Magnesium Alloy by Repeated Plastic Working and Solidifying Molding[J]. Materia. 2004, 43(4): 275-280
18 C. Yasumasa, H. Tetsuji, M. Mabuchi. Mechanical and Corrosion Properties of AZ31 Magnesium Alloy Repeatedly Recycled by Hot Extrusion. Materials Transactions. 2006, 47(4): 1040-1046
19吉泽升.日本镁合金研究进展及新技术.中国有色金属学报. 2004, 14 (12): 1977-1984
20 M. Nakanishi, M. Mabuchi. Tensile Properties of the ZK60 Magnesium Alloy Produced by Hot Extrusion of Machined Chip. Journal of Materials Science Letters. 1998, 17: 2003-2005
21潘国如,张佩武,刘英. AZ80镁合金切屑回用的探讨.特种铸造及有色合金. 2006, 26(7): 457-459
22 H. Watanabe, K. Moriwaki, T. Mukai. Consolidation of Machined Magnesium Alloy Chips by Hot Extrusion Utilizing Superplastic Flow[J]. Journal of Materials Science. 2001, 36: 5007-5011
23 F. Syuichi, I. Takanomi, K. Tetsuo. Microstructures and Mechanical Properties of Mg96Zn2Y2 Alloy Prepared by Extrusion of Machined Chips. Materials Transactions. 2009, 50(2): 349-353
24 C. Yasumasa, K. Masaaki. Blow Forming of Mg Alloy Recycled by Solid-state Recycling. Materials Transactions. 2004, 45(2): 361-364
25石凤健,汪建敏,许晓静.等截面角形挤压的研究内容及现状.热加工工艺.2003, 1: 51-53
26 Y. Li, T. G. Langdon. Equal-channel Angular Pressing of an Al-6061 Metalmatrix Composite. J.Mater.Sci. 2000,35: 1201-1204
27 V. M. Segal. Materianls Processing by Simple Shear. Mater. Sci. Eng. 1995, 197: 157-164
28许晓静,戈晓岚. SiC晶须增强铝基复合材料超塑性.复合材料学报. 2003, 20(3): 127-131
29 Y. Iwahashi, J. Wang, Z. Horita. Principle of Equal Channel Angular Pressing for the Processing of Ultrafine Grained Materials. Scr.Mater. 1996, 35(2): 143-146
30 T. Aida, K. Matsuki, Z. Horita, T. G. Langdon. Estimating the Equivalentstrain in Equal-channel Angular Pressing. Scr. Mater. 2001, 44: 575-579
31 M. Furukawa, Z. Hotita, M. Nemoto, T. G.. London. Processing of Metals by Equal-channel Angular Pressing. J.Mate.Sci. 2001,36: 2835-2843
32 A. Galiyev, R. Kaibyshev and G. Gottsein. Correlation of Plastic Deformation and Dynamic Recrystallization in Magnesium Alloy ZK60. Acta mater. 2001, 49: 1199~1207
33 M. Mabuchi, K. Ameyama, H. Iwasaki, K. Higashi. Low Temperature Superplasticity of AZ91 Magnesium Alloy with Non-equilibrium Grain Boundaries. Acta Mater. 1999, 47: 2047~2057
34 W. J. Kim, S. I. Hong, Y. S. Kim, S. H. Min, H. T. Jeong, J. D. Lee. Texture Development and its Effect on Mechanical Properties of an AZ61 Mg Alloy Fabricated by Equal Channel Angular Pressing. Acta Metall. 2003, 51: 3293~3307
35刘腾,张伟,吴世丁,姜传斌,李守新,徐永波.双相合金Mg-8Li-lAl的等通道转角挤压.金属学报. 2003, 39(8): 790~798
36 A. Yamashita, Z. Horita, T. G.. Langdon. Improving the Mechanical Properties of Magnesium and a Magnesium alloy Through Severe Plastic Deformation. Mater.Lett. 2001, A300: 142-147
37常海. ECAP变形对AZ91镁合金及SiCp/AZ91镁基复合材料显微组织和力学性能的影响.哈尔滨工业大学硕士学位论文. 2006:1~50
38 P. Quang, Y. G. Jeong, S. C. Yoon, S. H. Hong, H. S. Kim. Consolidation of 1vol.% Carbon Nanotube Reinforced Metal Matrix Nanocomposites via Equal Channel Angular Pressing. Journal of Materials Processing Technology. 2007, 187: 318-320
39 A. Tetsuo, T. Norio, M. Kenji, S. Kamado and Y. Kojima. Homogenusous Consolidation Process by ECAP for AZ31 Cutting chips. Journal of Materials. 2004, 54(11): 532-537
40 T. Aida, N. Takatsuji, K. Matsuki, S. Kamado and T. Satou. Mechanical Properties of SiC Particle-AZ31B Magnesium Alloy Machined Chips Composites Prepared by Extrusion after ECAP. Journal of Materials. 2008, 58(3): 104-110
41 K. T. Park, D. Y. Hwang, Y. K. Lee , Y. K. Kim, D. H. Shin. High Strain Rate Superplasticity of Submicrometer Grained 5083 Al Alloy Containing Scandium Fabricated by Severe Plastic Deformation. Mater. Sci. Eng. A. 2003, 34: 273~281
42 Y. Chino, M. Mabuchi. Deformation Characteristics of Recycled AZ91 Mg Alloy Containing Oxide Contaminants. Materials Transactions. 2008, 49(5): 1093-1100
43 K. Tanaka, T. Mori, T. Nakamura. Cavity formation at the interface of a spherical inclusion in a plastically deformed matrix. Philos. Mag. 1970, 21: 267-267
2胡茂良.固相合成AZ91D镁合金组织结构及性能研究.哈尔滨理工大学工学博士学位论文. 2008:1-20
3石凤健,汪建敏,许晓静.等截面角形挤压的研究内容及现状.热加工工艺. 2003, 1: 51-53
4 I. Sabirov, O. Kolednik, R.Z. Valiev, R. Pippan. Equal Channel Angular Pressing of Metal Matrix Composites: Effect on Particle Distribution and Fracture Toughness. Acta. Mater. 2005, 53(18): 4919-4930
5祁庆据,刘勇兵,杨晓红.镁合金的研究及其在汽车工业中的应用与展望.汽车工程. 2002, 24(2): 94-100
6凌人蛟.镁合金变形细化晶粒的研究现状.航天制造技术. 2007,5:28-31
7钟皓,陈琪,闫蕴琪,张慧,翁文凭. AZ31镁合金的热挤压组织与力学性能分析.轻金属. 2007, 3: 52-55
8张济洲.镁合金成型加工工艺关键措施探研.平顶山工学院学报. 2003, 12(4): 29-33
9马存真.镁及镁合金废料国际标准提案介绍及我国镁废料现状.世界有色金属. 2002, 6: 71-73
10王祝堂.今后10年镁屑增长率可达9.5%.轻合金加工技术. 2001, 29(3):17
11陈刚,范培耕,彭晓东,曹鹏军.镁合金废料回收与再生技术研究现状.兵器材料科学与工程. 2007, 30(5): 73-76
12王云,陈敏强,杨利坚,龙思远.镁合金废料的回收.铸造技术. 2007, 128: 27-32
13张泷,唐靖林,曾大本.镁合金废料再生技术现状及发展趋势.锻造. 2006, 55: 221-223
14李明照,马非.镁合金废料的回收与利用.华北工学院学报. 2005, 26(2):153-156
15孟若愚,张代东,原洪加.镁合金成型技术研究进展.金属铸锻焊技术. 2008, 37(7): 89-93
16陈晓瑜,吉泽升,胡茂良.镁合金固相合成和回收的研究进展.轻合金加工技术. 2007, 35(4): 10-13
17 K. Katsuyoshi, T. Ritsuko, W.B. Du. Manufacturing High Property Magnesium Alloy by Repeated Plastic Working and Solidifying Molding[J]. Materia. 2004, 43(4): 275-280
18 C. Yasumasa, H. Tetsuji, M. Mabuchi. Mechanical and Corrosion Properties of AZ31 Magnesium Alloy Repeatedly Recycled by Hot Extrusion. Materials Transactions. 2006, 47(4): 1040-1046
19吉泽升.日本镁合金研究进展及新技术.中国有色金属学报. 2004, 14 (12): 1977-1984
20 M. Nakanishi, M. Mabuchi. Tensile Properties of the ZK60 Magnesium Alloy Produced by Hot Extrusion of Machined Chip. Journal of Materials Science Letters. 1998, 17: 2003-2005
21潘国如,张佩武,刘英. AZ80镁合金切屑回用的探讨.特种铸造及有色合金. 2006, 26(7): 457-459
22 H. Watanabe, K. Moriwaki, T. Mukai. Consolidation of Machined Magnesium Alloy Chips by Hot Extrusion Utilizing Superplastic Flow[J]. Journal of Materials Science. 2001, 36: 5007-5011
23 F. Syuichi, I. Takanomi, K. Tetsuo. Microstructures and Mechanical Properties of Mg96Zn2Y2 Alloy Prepared by Extrusion of Machined Chips. Materials Transactions. 2009, 50(2): 349-353
24 C. Yasumasa, K. Masaaki. Blow Forming of Mg Alloy Recycled by Solid-state Recycling. Materials Transactions. 2004, 45(2): 361-364
25石凤健,汪建敏,许晓静.等截面角形挤压的研究内容及现状.热加工工艺.2003, 1: 51-53
26 Y. Li, T. G. Langdon. Equal-channel Angular Pressing of an Al-6061 Metalmatrix Composite. J.Mater.Sci. 2000,35: 1201-1204
27 V. M. Segal. Materianls Processing by Simple Shear. Mater. Sci. Eng. 1995, 197: 157-164
28许晓静,戈晓岚. SiC晶须增强铝基复合材料超塑性.复合材料学报. 2003, 20(3): 127-131
29 Y. Iwahashi, J. Wang, Z. Horita. Principle of Equal Channel Angular Pressing for the Processing of Ultrafine Grained Materials. Scr.Mater. 1996, 35(2): 143-146
30 T. Aida, K. Matsuki, Z. Horita, T. G. Langdon. Estimating the Equivalentstrain in Equal-channel Angular Pressing. Scr. Mater. 2001, 44: 575-579
31 M. Furukawa, Z. Hotita, M. Nemoto, T. G.. London. Processing of Metals by Equal-channel Angular Pressing. J.Mate.Sci. 2001,36: 2835-2843
32 A. Galiyev, R. Kaibyshev and G. Gottsein. Correlation of Plastic Deformation and Dynamic Recrystallization in Magnesium Alloy ZK60. Acta mater. 2001, 49: 1199~1207
33 M. Mabuchi, K. Ameyama, H. Iwasaki, K. Higashi. Low Temperature Superplasticity of AZ91 Magnesium Alloy with Non-equilibrium Grain Boundaries. Acta Mater. 1999, 47: 2047~2057
34 W. J. Kim, S. I. Hong, Y. S. Kim, S. H. Min, H. T. Jeong, J. D. Lee. Texture Development and its Effect on Mechanical Properties of an AZ61 Mg Alloy Fabricated by Equal Channel Angular Pressing. Acta Metall. 2003, 51: 3293~3307
35刘腾,张伟,吴世丁,姜传斌,李守新,徐永波.双相合金Mg-8Li-lAl的等通道转角挤压.金属学报. 2003, 39(8): 790~798
36 A. Yamashita, Z. Horita, T. G.. Langdon. Improving the Mechanical Properties of Magnesium and a Magnesium alloy Through Severe Plastic Deformation. Mater.Lett. 2001, A300: 142-147
37常海. ECAP变形对AZ91镁合金及SiCp/AZ91镁基复合材料显微组织和力学性能的影响.哈尔滨工业大学硕士学位论文. 2006:1~50
38 P. Quang, Y. G. Jeong, S. C. Yoon, S. H. Hong, H. S. Kim. Consolidation of 1vol.% Carbon Nanotube Reinforced Metal Matrix Nanocomposites via Equal Channel Angular Pressing. Journal of Materials Processing Technology. 2007, 187: 318-320
39 A. Tetsuo, T. Norio, M. Kenji, S. Kamado and Y. Kojima. Homogenusous Consolidation Process by ECAP for AZ31 Cutting chips. Journal of Materials. 2004, 54(11): 532-537
40 T. Aida, N. Takatsuji, K. Matsuki, S. Kamado and T. Satou. Mechanical Properties of SiC Particle-AZ31B Magnesium Alloy Machined Chips Composites Prepared by Extrusion after ECAP. Journal of Materials. 2008, 58(3): 104-110
41 K. T. Park, D. Y. Hwang, Y. K. Lee , Y. K. Kim, D. H. Shin. High Strain Rate Superplasticity of Submicrometer Grained 5083 Al Alloy Containing Scandium Fabricated by Severe Plastic Deformation. Mater. Sci. Eng. A. 2003, 34: 273~281
42 Y. Chino, M. Mabuchi. Deformation Characteristics of Recycled AZ91 Mg Alloy Containing Oxide Contaminants. Materials Transactions. 2008, 49(5): 1093-1100
43 K. Tanaka, T. Mori, T. Nakamura. Cavity formation at the interface of a spherical inclusion in a plastically deformed matrix. Philos. Mag. 1970, 21: 267-267