挤压比对Al-7.0Si-1.2Fe-0.3Mg合金热挤压组织和性能的影响
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摘要
采用金相显微镜(OM)、扫描电子显微镜(SEM)和拉伸力学测试等手段研究挤压比对Al-7.0Si-1.2Fe-0.3Mg合金组织、富铁相形态特征及力学性能的影响。研究结果表明:经过热挤压后,合金中的富铁相和共晶硅由铸造时的狭长板条状转变成均匀的短棒状,圆整度显著提高,但对第二相偏析的改善不明显。随着挤压比的增大,富铁相的破碎、细化效果逐渐增强,其平均等效粒径较铸态合金最大降低58.2%,而圆整度最大提高4.8倍;挤压比对共晶硅粒径影响不显著,但共晶硅的圆整度逐渐提高,最大幅度可达到76.2%。热挤压态合金抗拉强度随挤压比的增加,呈现先增加后降低的趋势,峰值出现在挤压比为40时,抗拉强度与铸态时相近,但延伸率随着挤压比的增大呈近似直线提高,较铸态提高约6倍。热挤压后合金的断裂类型由脆性断裂转变为韧性断裂,其显微硬度分布较为均匀,较铸态降低13.7%～20.6%;随着挤压比的增大,热挤压态合金显微硬度缓慢提高。
The effects of extrusion ratio on the microstructure, iron-rich phase morphology and mechanical properties of Al-7.0 Si-1.2 Fe-0.3 Mg alloy were studied by optical microscope(OM), scanning electron microscope(SEM) and tensile test. The results showed that the microstructure of second phases including iron-rich phase and eutectic silicon phase transformed to uniform short stick morphology from long and narrow needle-like morphology under as-cast, and the roundness of the second phases improved significantly, while the segregation of second phases had no obvious improvement. With the extrusion ratio increasing, the crushing and refining effect strengthened gradually, and the maximum reduction of average equivalent particle size of iron-rich phases reached 58.2% after hot extrusion compared to as-cast, while the roundness improved nearly 4.8 times compared to that of as-cast. The change of average equivalent particle size of eutectic silicon phase was not obvious, but the roundness improved by 76.2% maximally. The tensile testing results showed that the tensile strength after hot extruded exhibited the trend of increasing firstly and then decreased with the extrusion ratio increasing. The peak value appeared when extrusion ratio was up to 40, which was close to that of as-cast alloy. The elongation after hot extrusion was improved approximately linearly with the extrusion ratio increasing, and improved 6 times finally compared with the as-cast one. Moreover, the fracture type transformed from brittle fracture at as-cast to ductile fracture at hot extrusion. The microhardness distribution of hot extruded alloy exhibited uniformly, decreasing about 13.7%～20.6% compared to that of as-cast. Meanwhile, the microhardness value improved gradually with the extrusion ratio increasing.
The effects of extrusion ratio on the microstructure, iron-rich phase morphology and mechanical properties of Al-7.0 Si-1.2 Fe-0.3 Mg alloy were studied by optical microscope(OM), scanning electron microscope(SEM) and tensile test. The results showed that the microstructure of second phases including iron-rich phase and eutectic silicon phase transformed to uniform short stick morphology from long and narrow needle-like morphology under as-cast, and the roundness of the second phases improved significantly, while the segregation of second phases had no obvious improvement. With the extrusion ratio increasing, the crushing and refining effect strengthened gradually, and the maximum reduction of average equivalent particle size of iron-rich phases reached 58.2% after hot extrusion compared to as-cast, while the roundness improved nearly 4.8 times compared to that of as-cast. The change of average equivalent particle size of eutectic silicon phase was not obvious, but the roundness improved by 76.2% maximally. The tensile testing results showed that the tensile strength after hot extruded exhibited the trend of increasing firstly and then decreased with the extrusion ratio increasing. The peak value appeared when extrusion ratio was up to 40, which was close to that of as-cast alloy. The elongation after hot extrusion was improved approximately linearly with the extrusion ratio increasing, and improved 6 times finally compared with the as-cast one. Moreover, the fracture type transformed from brittle fracture at as-cast to ductile fracture at hot extrusion. The microhardness distribution of hot extruded alloy exhibited uniformly, decreasing about 13.7%～20.6% compared to that of as-cast. Meanwhile, the microhardness value improved gradually with the extrusion ratio increasing.
引文
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[6] Murali S, Raman KS, Murthy K S S. The formation of β-FeSiAl5 and Be-Fe phases in Al-7Si-0.3Mg alloy containing Be [J]. Materials Science and Engineering A, 1995, 190(1-2): 165.
[7] Samuel A M, Samuel F H, Dotty H W. Observation on the formation of β-Al5FeSi phase in 319 type Al-Si alloys [J]. J. Materials Science, 1996, 31(20): 5529.
[8] Tan X P, Zheng K H, Song D F, Zhang X M. Effects of A1-3B master alloy addition on impurity iron content of recycled casting aluminum alloy [J]. Chinese Journal of Nonferrous Metals, 2014, 24(6): 1401. (谭喜平, 郑开宏, 宋东福, 张新明. Al-3B中间合金添加量对再生铸造铝合金中杂质铁含量的影响 [J]. 中国有色金属学报, 2014, 24(6): 1401.)
[9] Wang J M, Li Z F, Zhang R Y. The study of rare earth′s effect on aluminum-silicon alloy structure [J]. Light Alloy Fabrication Technology, 2005, 33(3): 47.
[10] Tzeng Y C, Wub C T, Bor H Y, Horng J L, Tsai M L, Lee S L. Effects of scandium addition on iron-bearing phases and tensile properties of Al-7Si-0.6Mg alloys [J]. Materials Science & Engineering A, 2014, 593: 103.
[11] Zhang L, Jiao W L, Yu H J, Yao G C. Influence of manganese and pre-heat treatment on microstructure and mechanical properties of Al- Si alloy [J]. Chinese Journal of Nonferrous Metals, 2005,15(3): 368. (张磊, 焦万丽, 尉海军, 姚广春. 锰结合预先热处理对铝硅合金中富铁相组织和力学性能的影响 [J]. 中国有色金属学报, 2005, 15(3): 368.)
[12] Seifeddine S, Johansson S, Svensson I L. The influence of cooling rate and manganese content on the β-Al5FeSi phase formation and mechanical properties of Al-Si-based alloys [J]. Materials Science and Engineering A, 2008, 490(1-2): 385.
[13] Shabestari S G, Parshizfard E. Effect of semi-solid forming on the microstructure and mechanical properties of the iron containing Al-Si alloys [J]. Journal of Alloys & Compounds, 2011, 509(509): 7973.
[14] Lin C, Wu S S, Zhong G, Wan L, An P. Effect of ultrasonic vibration on Fe-containing intermetallic compounds of hypereutectic Al-Si alloys with high Fe content [J]. Transactions of Nonferrous Metals Society of China, 2013, 23(5): 1245.
[15] Song D F, Wang S C, Zhou N, Xu J, Zheng K H. Iron-rich phase morphology characteristics for Al-Si alloy by Mn addition and melt holding [J]. Chinese Journal of Rare Metals, 2017, 41(7): 739.(宋东福, 王顺成, 周楠, 徐静, 郑开宏. 锰结合熔体保温对铝硅合金中富铁相特征的影响 [J]. 稀有金属, 2017, 41(7): 739.)
[16] Shabestaria S G, Ghanbarib M. Effect of plastic deformation and semisolid forming on iron-manganese rich intermetallics in Al-8Si-3Cu-4Fe-2Mn alloy [J]. Journal of Alloys and Compounds, 2010, 508(2): 315.
[17] Eshaghi A, Ghasemi H M, Rassizadehghani J. Effect of heat treatment on microstructure and wear behavior of Al-Si alloys with various iron contents [J]. Materials and Design, 2011, 32(3): 1520.
[18] Villeneuve C, Samuel F H. Fragmentation and dissolution of β-Al5FeSi phase during solution heat treatment of Al-Si-Fe alloys [J]. Int. J. Cast. Metals. Res., 1999, 12(3): 145.
[2] Murali S, Row T N, Sastery D H, Raman K S, Murthy K S S. Crystal Structure of β-FeSiAl5 and (BeFe)-BeSiFe2Al8 phases [J]. Scripta Metallugica et Materialia, 1994, 31(3): 267.
[3] Song D F, Wang S C, Zheng K H. Effects of Mn/Fe mole ratio on iron-rich phase morphology of A356 cast aluminum alloy [J]. Chinese Journal of Nonferrous Metals, 2015, (7): 1832.(宋东福, 王顺成, 郑开宏. Mn/Fe摩尔比对A356铸造铝合金富铁相形态的影响 [J]. 中国有色金属学报, 2015, (7): 1832.)
[4] Lin B, Zhang W W, Niu J Y, Luo Z, Zhao Y L, Meng F S. Tensile fracture behavior of Al-Cu cast alloys with iron-rich intermetallic [J]. Chinese Journal of Rare Metals, 2017, 41(3): 225.(林波, 张卫文, 牛嘉运, 罗执, 赵愈亮, 孟凡生. 铸造Al-Cu合金中富铁相对拉伸断裂行为的影响 [J]. 稀有金属, 2017, 41(3): 225.)
[5] Shabestari S G. The effect of iron and manganese on the formation of intermetallic compounds in aluminum-silicon alloys [J]. Materials Science and Engineering A, 2004, 383(2): 289.
[6] Murali S, Raman KS, Murthy K S S. The formation of β-FeSiAl5 and Be-Fe phases in Al-7Si-0.3Mg alloy containing Be [J]. Materials Science and Engineering A, 1995, 190(1-2): 165.
[7] Samuel A M, Samuel F H, Dotty H W. Observation on the formation of β-Al5FeSi phase in 319 type Al-Si alloys [J]. J. Materials Science, 1996, 31(20): 5529.
[8] Tan X P, Zheng K H, Song D F, Zhang X M. Effects of A1-3B master alloy addition on impurity iron content of recycled casting aluminum alloy [J]. Chinese Journal of Nonferrous Metals, 2014, 24(6): 1401. (谭喜平, 郑开宏, 宋东福, 张新明. Al-3B中间合金添加量对再生铸造铝合金中杂质铁含量的影响 [J]. 中国有色金属学报, 2014, 24(6): 1401.)
[9] Wang J M, Li Z F, Zhang R Y. The study of rare earth′s effect on aluminum-silicon alloy structure [J]. Light Alloy Fabrication Technology, 2005, 33(3): 47.
[10] Tzeng Y C, Wub C T, Bor H Y, Horng J L, Tsai M L, Lee S L. Effects of scandium addition on iron-bearing phases and tensile properties of Al-7Si-0.6Mg alloys [J]. Materials Science & Engineering A, 2014, 593: 103.
[11] Zhang L, Jiao W L, Yu H J, Yao G C. Influence of manganese and pre-heat treatment on microstructure and mechanical properties of Al- Si alloy [J]. Chinese Journal of Nonferrous Metals, 2005,15(3): 368. (张磊, 焦万丽, 尉海军, 姚广春. 锰结合预先热处理对铝硅合金中富铁相组织和力学性能的影响 [J]. 中国有色金属学报, 2005, 15(3): 368.)
[12] Seifeddine S, Johansson S, Svensson I L. The influence of cooling rate and manganese content on the β-Al5FeSi phase formation and mechanical properties of Al-Si-based alloys [J]. Materials Science and Engineering A, 2008, 490(1-2): 385.
[13] Shabestari S G, Parshizfard E. Effect of semi-solid forming on the microstructure and mechanical properties of the iron containing Al-Si alloys [J]. Journal of Alloys & Compounds, 2011, 509(509): 7973.
[14] Lin C, Wu S S, Zhong G, Wan L, An P. Effect of ultrasonic vibration on Fe-containing intermetallic compounds of hypereutectic Al-Si alloys with high Fe content [J]. Transactions of Nonferrous Metals Society of China, 2013, 23(5): 1245.
[15] Song D F, Wang S C, Zhou N, Xu J, Zheng K H. Iron-rich phase morphology characteristics for Al-Si alloy by Mn addition and melt holding [J]. Chinese Journal of Rare Metals, 2017, 41(7): 739.(宋东福, 王顺成, 周楠, 徐静, 郑开宏. 锰结合熔体保温对铝硅合金中富铁相特征的影响 [J]. 稀有金属, 2017, 41(7): 739.)
[16] Shabestaria S G, Ghanbarib M. Effect of plastic deformation and semisolid forming on iron-manganese rich intermetallics in Al-8Si-3Cu-4Fe-2Mn alloy [J]. Journal of Alloys and Compounds, 2010, 508(2): 315.
[17] Eshaghi A, Ghasemi H M, Rassizadehghani J. Effect of heat treatment on microstructure and wear behavior of Al-Si alloys with various iron contents [J]. Materials and Design, 2011, 32(3): 1520.
[18] Villeneuve C, Samuel F H. Fragmentation and dissolution of β-Al5FeSi phase during solution heat treatment of Al-Si-Fe alloys [J]. Int. J. Cast. Metals. Res., 1999, 12(3): 145.
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