热机械加工对Al-13.0Zn-3.16Mg-2.8Cu-0.2Zr-0.07Sr合金组织与性能的影响

Effect of thermo-mechanical processing on microstructure and properties of Al-13.01Zn-3.16Mg-2.8Cu-0.204Zr-0.0757Sr aluminum alloy

采用X射线衍射分析(XRD)、电子背散射衍射分析(EBSD)、电导率测试、硬度测试、晶间腐蚀试验和剥落腐蚀试验,研究了预回复固溶时效处理前的热机械加工(Thermo-mechanical processing,TMP)对超高强铝合金Al-13.01Zn-3.16Mg-2.8Cu-0.2Zr-0.07Sr组织及性能的影响。结果表明,TMP(450℃/2 h+460℃/2 h+470℃/2 h(水淬)固溶、400℃/24 h过时效、约45%压缩量)处理后降低了合金的位错密度(0.150→0),减小了平均晶粒尺寸(6.256μm→5.012μm)和平均晶界角度,显著提高了低角度晶界数目百分比(0.618→0.700),电导率(25.3%IACS→27.2%IACS)和伸长率(8.1%→8.2%)基本未发生变化,降低了硬度(229.6 HV→221.0 HV)、屈服强度(653.8 MPa→599.5 MPa)、抗拉强度(701.9 MPa→646.3 MPa),提高了抗晶间腐蚀和抗剥落腐蚀性能。定量分析显示,热机械加工轻微提高了合金位错强化、低角度晶界强化和高角度晶界强化的总强化,合金强度的降低主要归因于合金固溶强化和时效沉淀析出相强化的总强化的降低。抗腐蚀性能的提高可以归因于合金低角度晶界数目百分比的提高。

Effect of thermo-mechanical processing（TMP） on microstructure and properties before prerecovery solution aging treatment of ultra- high strength aluminum alloy Al-13.01Zn-3.16Mg-2. 8Cu-0. 204Zr-0. 0757Sr was investigated by means of XRD, EBSD technique, conductivity, hardness, tensile, inter-granular corrosion and exfoliation corrosion tests. The results show that the dislocation density, average grain size, average misorientation angle, hardness, yield strength and tensile strength of the alloy decrease after treatment by TMP, while low angle grain boundary proportion, intergranular corrosion and exfoliation corrosion resistance increase, conductivity and elongation of the alloy are unchanged. Quantitative analysis shows that the TMP slightly enhances the effects of the strengthening of dislocation, low angle grain boundaries and high angle grain boundaries, and the decrease of strength can be attributed to the reducing of solid solution strengthening and aging precipitated phase strengthening. The increase of corrosion resistance is due to the increase of the low angle grain boundary number percentage.