Effects of Intensification Pressure on Hot Tearing Susceptibility of Al-Zn-Mg-Cu Alloy Casting

Tao Xingyu; Wu Guoqiang; Zhao Junwen; Huang Xingmin; Han Jing; Zhang Xu

doi:10.15980/j.tzzz.2022.02.017

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Effects of Intensification Pressure on Hot Tearing Susceptibility of Al-Zn-Mg-Cu Alloy Casting
Vol. 42, Issue 2, Pages: 215-220(2022)
Published： 2022 ，
DOI： 10.15980/j.tzzz.2022.02.017

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Tao Xingyu, Wu Guoqiang, Zhao Junwen, et al. Effects of Intensification Pressure on Hot Tearing Susceptibility of Al-Zn-Mg-Cu Alloy Casting. [J]. Special Casting & Nonferrous Alloys 42(2):215-220(2022)
DOI：

Tao Xingyu, Wu Guoqiang, Zhao Junwen, et al. Effects of Intensification Pressure on Hot Tearing Susceptibility of Al-Zn-Mg-Cu Alloy Casting. [J]. Special Casting & Nonferrous Alloys 42(2):215-220(2022) DOI： 10.15980/j.tzzz.2022.02.017.

摘要

采用半定量热裂倾向评定方法对Al-Zn-Mg-Cu合金半固态流变压铸件的热裂倾向性（HTS）进行评估，分析了不同增压比压下铸件的热裂断口形貌及截面孔洞分布。结果表明，增压比压为67～94 MPa时，合金热裂倾向随增压比压的提高呈先减小后增大的趋势，在增压比压为87 MPa时热裂倾向系数最小为15

继续提高至94 MPa时，热裂倾向最高，H

值为27。试样内部孔洞对热裂影响程度最为剧烈，是热裂纹萌生的起源。合金凝固补缩不足时导致的晶间分离是孔洞产生的主要原因，提高增压比压可以有效降低铸件的孔隙率，但太高的增压比压会给正在凝固的铸件形成冲击力作用，使铸件开裂并加剧热裂倾向。

Abstract

The hot tearing susceptibility（HTS） of Al-Zn-Mg-Cu alloy semi-solid rheo-die castings was evaluated by the semi-quantitative evaluation method. The fracture morphology and the distribution of cross-section pores were analyzed under different intensification pressures. The results reveal that the H

of the alloy is decreased firstly and then increased with the increase of intensification pressure

and presents the smallest H

value of 15 when the intensification pressure is 87 MPa. With 94 MPa

the H

has the highest value of 27. The pores inside the samples have a strong influence on hot tearing

which is the origination of the hot tearing initiation. The intergranular separation caused by insufficient shrinkage during solidification is the main cause of pores

and the porosity of castings can be effectively reduced by increasing intensification pressures. However

the higher intensification pressure will exert an impact on the solidifying casting

leading to crack and increase of hot tearing.