淬火及预拉伸对铝锂合金板材残余应力的影响

Effects of quenching and pre-strenching on residual stress of Al-Li alloy plate

通过有限元分析与钻孔法残余应力测试相结合,研究了淬火介质参数、预拉伸对铝锂合金板材淬火残余应力分布与演变的影响。结果表明:淬火介质冷却速率越慢,板材残余应力越小,淬火介质对合金冷却能力由大到小的顺序为10%NaCl>水>5%PAG;随着预拉伸量的增加,板材表层压应力减小,并逐渐转变为拉应力。预拉伸量为2.5%时,残余应力绝对值稳定在25 MPa内。有限元点追踪表明,在40℃水温淬火过程中,板材体中心点(A)与上表面中心(B)在三个方向上的残余应力变化规律相反,最终均呈平面应力状态;而板材宽向线中心(C)与长向线中心(D)演变规律相似,但分应力的方向不同;板材顶点(E)在三个方向上的残余应力均较小。

Combined with finite element analysis and drilling residual stress test,the effects of quenching medium parameters and pre-stretching on the distribution and evolution of residual stress of Al Li alloy plate were studied.The results show that the slower the cooling rate of quenching medium is,the smaller the residual stress is.The cooling capacity of different quenchants from high to low is 10%NaCl>water>5%PAG.With the increase of pre-strenching amount,the compressive stress on the surface of the plate decreases and gradually changes into tensile stress.When the pre-strenching amount is 2.5%,the absolute value of residual stress is stable within 25 MPa.The finite element point tracing shows that during the quenching process at 40℃,the variations of residual stresses in the three directions of the center(A)and the center(B)of the upper surface of the plate are opposite,and all of them are in the plane stress state;while the evolutions of the center(C)along ND and the center(D)along RD of the plate are similar,but the direction of the partial stresses are different;the residual stresses of the top(E)in three directions of the plate are all smaller.