比压对Al-Zn-Mg-Cu合金压铸件热裂倾向的影响  

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

作　　者：陶星宇 巫国强 赵君文[1] 黄兴民[1] 韩靖[1] 张旭[2] Tao Xingyu;Wu Guoqiang;Zhao Junwen;Huang Xingmin;Han Jing;Zhang Xu(School of Materials Science and Engineering,Southwest Jiaotong University;School of Mechanics and Aerospace Engineering,Southwest Jiaotong University)

机构地区：[1]西南交通大学材料科学与工程学院,成都610031 [2]西南交通大学力学与航空航天学院

出　　处：《特种铸造及有色合金》2022年第2期215-220,共6页Special Casting & Nonferrous Alloys

基　　金：汽车高性能材料及成形技术四川省高校重点实验室开放基金资助项目(szjj2017-019)。

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_(TS)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。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_(TS)of the alloy is decreased firstly and then increased with the increase of intensification pressure, and presents the smallest H_(TS)value of 15 when the intensification pressure is 87 MPa. With 94 MPa, the H_(TS)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.

关 键 词：AL-ZN-MG-CU 流变压铸 增压比压 热裂 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG249.2[金属学及工艺—金属材料]