升温速率对2219铝合金蠕变时效行为的影响

Effect of Heating Rate on Creep Aging Behavior of 2219 Aluminum Alloy

研究2219铝合金在蠕变时效成形过程中,升温速率对其蠕变行为及力学性能的影响规律。实验模拟构件在热压罐中的升温条件,降低材料的升温速率(0.75℃/min),延长其升温时间至4h(某典型构件真实蠕变时效升温时间),分别在0,150,210MPa 3种应力条件及不同的时效时间下进行蠕变实验,并对材料拉伸力学性能和微观组织(TEM)进行分析。结果表明:对比在材料尺度下0.5h的升温条件(5.5℃/min),升温速率的降低,在一定程度上提高了材料的力学性能,并且延长了材料强度达到峰值的时间;铝合金析出相的形状因子随着时效时间呈现先增长,到达峰值后下降的趋势;降低升温速率,材料在升温阶段即已发生了显著蠕变形变,在150MPa和210MPa应力条件下升温阶段的蠕变量分别占总蠕变量的29.28%和21.56%,且蠕变变形量和稳态蠕变速率会随着应力的升高而增加;由此,基于材料尺度(标准蠕变试样)的蠕变时效研究,用于表征构件尺度蠕变时效行为时,须进一步考虑升温速率对其成形及性能演变的影响。

Effect of heating rate on creep aging behavior and mechanical properties in the process of creep aging forming of 2219 aluminum alloy was studied.In order to simulate the temperature conditions of the component in autoclave,heating rate was reduced to 0.75℃/min and heating time was prolonged to 4 h(real creep aging heating time for a typical component).Creep aging experiments were carried out under three kinds of stress conditions of 0,150,210 MPa and different aging time,tensile mechanical properties and microstructures(TEM)of materials were analyzed.The results show that lowering heating rate improves mechanical properties of material and prolongs the arrival time of material strength peak compared to heating time of 0.5 h(5.5℃/min)in material standard;shape factor of precipitate phase of aluminum alloy increases with the aging time,and then decreases after reaching the peak;when lowering heating rate,significant creep deformation occurs in materials heating stage,creep strain of heating stage are accounted for 29.28% and 21.56% of total creep strain in two kinds of stress conditions of 150 MPa and 210 MPa,creep strain and steady-state creep rate increase with the rise of stress;therefore,it is necessary to further consider the effect of heating rate on the forming and mechanical property evolution in the study on the characterization of creep aging behavior of component based on the creep aging research of material standard(standard creep specimen).