人工时效前停放时间对7055铝合金挤压管显微组织与性能的影响

Influence of conditioning time before artificial aging on the microstructure and properties of 7055 aluminium alloy extruded tube

  • 摘要: 采用维氏硬度试验,室温拉伸试验,电导率测试,慢应变拉伸试验和透射电镜等方法,对人工时效前室温停放不同时间的7055铝合金管材的力学性能、电导率、耐应力腐蚀性能和微观组织进行了研究.结果表明:在人工时效前进行室温停放,7055铝合金的晶内会预先析出GP区,为后续人工时效中的η相和η'相的析出提供形核的核心,从而有效地提高合金的力学性能和电导率.人工时效前室温停放6.5 h,7055铝合金的抗拉强度达到最大值即677.9 MPa,电导率和延伸率分别为29.8 % IACS和14.9 %.继续延长室温停放时间,合金的抗拉强度降低,电导率不断增大.在室温停放48 h时,合金的抗拉强度达到649.7 MPa,延伸率为10.6 %,电导率为36.8 % IACS,此时合金的综合性能达到较优.

     

    Abstract: The effect of conditioning time before artificial aging on the microstructure and properties of 7055 aluminum alloy extruded pipe was investigated by means of Vickers hardness test, room temperature tensile test, electrical conductivity test, slow strain tensile test and transmission electron microscopy (TEM). The results showed that GP region was precipitated first during the conditioning time, and provided nucleation sites for η and η', phases so that the nucleation density of η and η', phases increased. Therefore, the electrical conductivity and mechanical properties of the alloy improved. The tensile strength, elongation and electrical conductivity of the 7055 aluminium alloy were 677.9 MPa, 14.9 %, 29.8 % IACS, respectively, when the conditioning time was 6.5 h. With the prolongation of the conditioning time before artificial aging, the tensile strength of the alloy decreased and its conductivity increased. When the conditioning time was 48h, the tensile strength, elongation rate and electrical conductivity of 7055 aluminium alloy were 649.7 MPa, 10.6 %, 36.8 % IACS, respectively, and the alloy acquired its best comprehensive properties.

     

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