新型铝锌镁铜系高强韧铝合金型材的双级时效工艺

Two-step Aging Treatment for a New Al-Zn-Mg-Cu Type of High Strength-Tough Aluminum Alloy Profile

通过时效处理和拉伸性能测试等方法得到了适用于一种新型铝锌镁铜系高强韧铝合金挤压型材的双级时效工艺。结果表明:在双级时效处理后该合金的析出相主要为η′相和少量的η相,随着二级时效时间的延长,η相数量增加,沉淀相尺寸增大;试验合金的硬度随着时效时间的延长先增大后减小,强度随二级时效时间的延长而下降,伸长率则增大;得到合适的时效工艺为120℃×4h+165℃×6h,经该时效工艺处理后试验合金的抗拉强度为566 MPa,屈服强度为540 MPa,伸长率为10.9%,电导率为40.8%IACS,优于T74态7050铝合金的。

A suitable two-step aging treatment for a new Al-Zn-Mg-Cu type of high strength-tough aluminum alloy profile was obtained by aging treatment and tensile test methods. The results show that the precipitates in the alloy mainly consisted of rI＇ and rI phase after the two step aging treatment, and the amounts of the η phases increased and the dimensions of the precipitates enlarged with the prolonging of the 2nd step aging time. The hardness of the alloy first increased then decreased with the increase of the aging time, and the strength decreased while the elongation increased with the increase of the 2^nd step aging time. The two-step aging process of aging at 120 ℃ for 4 h followed by a re-aging at 165 ℃ for 6 h was determined as a suitable one. After treated by the suitable aging treatment, the tensile strength, yield strength, elongation and electrical conductivity of the alloy were 566 MPa, 540 MPa, 10.9% and 40.8% IACS respectively, and were better than those of 7050-T74 aluminum alloy.