新型回归再时效优化对Al-Zn-Mg-Cu合金组织和性能的影响

Effect of new RRA aging regression treatment optimization on microstructure and properties of Al-Zn-Mg-Cu alloy

  • 摘要: 通过在回归阶段之后加入24 h自然时效,设计了新型的多级时效制度。本文以石油钻探杆用Al-Zn-Mg-Cu合金挤压管材为研究对象,采用拉伸测试和电化学腐蚀测试手段,研究了经过不同回归时效处理制度处理后合金的拉伸性能和耐腐蚀性能。通过扫描显微镜、透射显微镜观察不同时效制度处理后合金的微观组织,并对相关机理进行了探究分析。在优化新型多级时效制度时发现,提高回归温度或延长回归时间会使合金的拉伸强度下降,耐腐蚀性能提高。经过优化,确定了新型多级时效工艺的较优参数为:100 ℃/24 h+168 ℃/4 h+水淬+(自然时效,NA)/24 h+80 ℃/34 h。经过该时效处理后,合金的抗拉强度为672 MPa,屈服强度为628 MPa,延伸率为10.5%,自腐蚀电流密度为6.29 μA/cm2,具有较优的综合性能。

     

    Abstract: After the regression stage, 24 h natural aging was added to design a new multi-stage aging process. This paper studies the mechanical properties and corrosion resistance of Al-Zn-Mg-Cu alloy treated by different regression aging treatment systems using a tensile test and electrochemical corrosion test using an Al-Zn-Mg-Cu alloy extrusion tube for oil drilling rods. After different aging heat treatments, the alloy’s microstructure was observed by scanning electron microscope and transmission electron microscope, and the related mechanism was explored and analyzed. When optimizing the new multi-stage aging system, it is found that increasing the regression temperature or prolonging the regression time can decrease the tensile strength and improve the corrosion resistance of the alloy. After optimization, the optimal parameters of the RRA aging process are determined as 100 ℃/24 h+168 ℃/4 h+ water quenching +NA/24 h+80 ℃/34 h. After the aging treatment, the alloy has the best comprehensive properties. After the aging treatment, the tensile strength of the alloy is 672 MPa, the yield strength is 628 MPa, the elongation is 10.5%, and the self-etching current density is 6.29 μA/cm2.

     

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