Effect of Si content and heat treatment on microstructure and properties of as-cast Al-Si alloy

doi:10.13251/j.issn.0254-6051.2020.08.015

Abstract

Abstract: In order to improve its mechanical properties, the effect of Si content and heat treatment on the microstructure and properties of the as-cast Al-Si alloy was studied systematically. The results show that the effect of Si content, cooling medium, solution treatment temperature, aging time and aging temperature on the hardness of the alloy decreases in turn. The optimal Si content and the optimal heat treatment process are 12% Si and solid solution treating at 480 ℃ for 120 min+salt bath cooling+aging at 175 ℃ for 90 min, respectively. With the increase of Si content, the hardness and tensile strength of the alloy increase; but when the Si content is too high, the precipitation of block-shaped primary silicon tends to form stress concentration then reduces the strength of the alloy, and the fracture mode changes from ductile fracture to cleavage fracture. The eutectic silicon in as-cast Al-Si alloy is long needle like. After using the optimal heat treatment, the long needle-like silicon transforms into short rod or granular shape, and the eutectic silicon is more dispersed, the stress concentration decreases during tension, and the dislocation movement resistance increases, all of which improve the mechanical properties of the Al-Si alloy.

Key words: Al-Si alloy, heat treatment, Si content, microstructure, mechanical properties

CLC Number:

TG166.3

Tang Peng, Liu Yiyuan, Zhao Yanjun, Hu Zhiliu, Wang Huachun, Peng Linxin, Deng Songyun. Effect of Si content and heat treatment on microstructure and properties of as-cast Al-Si alloy[J]. Heat Treatment of Metals, 2020, 45(8): 76-81.

References

[1]Tang Peng, Hu Zhiliu, Zhao Yanjun, et al. Investigation on the solidification course of Al-Si alloys by using a numerical Newtonian thermal analysis method[J]. Materials Research Express, 2017, 12(4): 1-9.
[2]尹昕, 尹登峰, 王凯先, 等. 添加0.2%Sn对Al-Si-Mg合金组织及力学性能的影响[J]. 金属热处理, 2020, 45(4): 16-21.
Yin Xin, Yin Dengfeng, Wang Kaixian, et al. Effect of 0.2%Sn addition on microstructure and mechanical properties of Al-Si-Mg alloy[J]. Heat Treatment of Metals, 2020, 45(4): 16-21.
[3]井婷婷, 赵玉厚, 郭永春, 等. Al-Si合金热处理工艺研究[J]. 热加工工艺, 2019, 48(24): 133-135.
Jing Tingting, Zhao Yuhou, Guo Yongchun, et al. Study on heat treatment process of Al-Si alloy[J]. Hot Working Technology, 2019, 48(24): 133-135.
[4]黄志翔, 闫洪, 王志伟. 锶变质及热处理对ADC12合金显微组织及力学性能的影响[J]. 中南大学学报, 2018, 25(6): 1263-1273.
Huang Zhixiang, Yan Hong, Wang Zhiwei. Microstructure and mechanical properties of strontium-modified ADC12 alloy processed by heat treatment[J]. Journal of Central South University, 2018, 25(6): 1263-1273.
[5]胡治流, 黄惠毅, 唐鹏, 等. Fe对Al-10Si合金微观组织和摩擦性能的影响[J]. 材料研究与应用, 2019, 13(1): 1-7.
Hu Zhiliu, Huang Huiyi, Tang Peng,et al. Effect of Fe on microstructure and tribological properties of Al-10Si alloy[J]. Materials Research and Application, 2019, 13(1): 1-7.
[6]黄元春, 杨楚戈, 刘宇, 等. 2219铝合金铸锭均匀化热处理工艺[J]. 金属热处理, 2016, 41(12): 92-97.
Huang Yuanchun, Yang Chuge, Liu Yu, et al. Homogenization heat treatment of 2219 aluminum alloy ingots[J]. Heat Treatment of Metals, 2016, 41(12): 92-97.
[7]Gupta A K, Prasad B K, Pajnoo R K, 等. T6热处理对共晶Al-Si合金力学性能、耐磨和抗蚀性能的影响[J]. 中国有色金属学报, 2012, 22(5): 1041-1050.
Gupta A K, Prasad B K, Pajnoo R K, et al. Effects of T6 heat treatment on mechanical, abrasive and erosive-corrosive wear properties of eutectic Al-Si alloy [J]. Transactions of Nonferrous Metals Society of China, 2012, 22(5): 1041-1050.
[8]孙艳容, 王杰, 杨锦, 等. 热处理制度对IN718变形合金组织和性能的影响[J]. 金属热处理, 2018, 43(12): 152-159.
Sun Yanrong, Wang Jie, Yang Jin, et al. Effect of heat treatment on microstructure and mechanical properties of IN718 deformed alloy[J]. Heat Treatment of Metals, 2018, 43(12): 152-159.
[9]Wang Kang, Tang Peng, Huang Yi,et al. Characterization of microstructures and tensile properties of recycled Al-Si-Cu-Fe-Mn alloys with individual and combined addition of titanium and cerium[J]. Scanning, 2018, 12(1): 1-9.
[10]徐松, 吉泽升, 许红雨, 等. 镁含量对挤压铸造Al-10Si-2.5Cu-xMg合金显微组织及力学性能的影响[J]. 金属热处理, 2019, 44(4): 10-14.
Xu Song, Ji Zesheng, Xu Hongyu, et al. Effect of Mg content on microstructure and mechanical properties of squeeze casting Al-10Si-2.5Cu-xMg alloy[J]. Heat Treatment of Metals, 2019, 44(4): 10-14.
[11]康福伟, 弥宁, 李晨, 等. 变质及熔体处理对过共晶铝硅合金组织的影响[J]. 哈尔滨理工大学学报, 2013, 18(4): 117-120.
Kang Fuwei, Mi Ning, Li Chen, et al. The effects of modification and melt treatment on the microstructure of hypereutectic Al-Si alloy[J]. Journal of Harbin University of Science and Technology, 2013, 18(4): 117-120.
[12]Han Nianmei, Zhang Xinming, Liu Shengdan, et al. Effects of pre-stretching and aging on the strength and fracture toughness of aluminum alloy 7050[J]. Materials Science and Engineering A, 2011, 528(10/11): 3714-3721.
[13]唐鹏, 覃皓, 赵艳君, 等. 双级时效工艺对富铁ADC12铝合金组织和硬度的影响[J]. 广西大学学报(自然科学版), 2016, 41(5): 1702-1708.
Tang Peng, Qin Hao, Zhao Yanjun, et al. Influence of duplex aging on the microstructure and hardness of Fe-rich ADC12 aluminum alloy[J]. Journal of Guangxi University, 2016, 41(5): 1702-1708.
[14]Dang Bo, Jian Zengyun, Xu Junfeng, et al. Effect of phosphorus and heat treatment on microstructure of Al-25%Si alloy[J]. China Foundry, 2017, 14(1): 10-15.
[15]田振乾, 魏坤霞, 魏伟, 等. 深冷处理铝硅合金的微观组织与力学性能[J]. 金属热处理, 2017, 42(2): 54-58.
Tian Zhenqian, Wei Kunxia, Wei Wei, et al. Microstructure and mechanical properties of Al-Si alloy by deep cryogenic treatment[J]. Heat Treatment of Metals, 2017, 42(2): 54-58.
[16]Tang Peng, Li Wenfang, Wang Kang, et al. Effect of Al-Ti-C master alloy addition on microstructures and mechanical properties of cast eutectic Al-Si-Fe-Cu alloy[J]. Materials and Design, 2017, 115(2): 147-157.
[17]朱上, 李志辉, 闫丽珍, 等. Zn添加对预时效态Al-Mg-Si-Cu合金自然时效和烘烤硬化性的影响[J]. 金属学报, 2019, 55(11): 1395-1406.
Zhu Shang, Li Zhihui, Yan Lizhen, et al. Effects of Zn addition on the natural aging behavior and bake hardening response of a pre-aged Al-Mg-Si-Cu alloy[J]. Acta Metallurgica Sinica, 2019, 55(11): 1395-1406.