应力时效影响Al-10Zn-3Mg-3Cu合金带外纵筋筒形件组织性能研究

Effect of Stress-aging on Microstructure and Mechanical Properties of Al-10Zn-3Mg-3Cu Alloy Cylindrical Parts with External Longitudinal Ribs

目的研究应力时效条件下Al-10Zn-3Mg-3Cu合金带外纵筋筒形件筋部试样的应力松弛行为,探明基体应力松弛机制以及强韧性协同提升机理。方法针对淬火态筋部试样,设计不同的初始应力值进行应力时效实验,然后采用数据分析与微观组织形貌表征方法研究试样组织性能。结果当施加的初始应力为250MPa时,筋部试样的应力松弛程度可达85.8%,同时,试样抗拉强度为736.40 MPa,屈服强度为697.53 MPa,延伸率为10.96%。结论在250MPa应力时效条件下,应力松弛机制主要为晶界Coble蠕变和位错运动,位错运动促进了亚晶的增殖,Coble蠕变使基体晶粒长大,这些行为促使试样应力耗散。同时,应力时效改变了析出相形态,发展了具有孪生界面的复合析出相。经分子动力学计算可知,该特征微结构有利于基体强韧性的协同提升。

The work aims to investigate the stress relaxation behavior of Al-10Zn-3Mg-3Cu alloy with external longitudinal reinforcement under stress aging conditions,and to clarify the mechanism of matrix stress relaxation and the mechanism of en-hancing toughness and strength.For the quenched reinforcement samples,different initial stress values were designed to carry out stress aging experiments.Then,the microstructure and properties of the samples were studied through data analysis and mi-crostructure characterization.When the initial stress was 250 MPa,the stress relaxation degree of the reinforcement samples reached 85.8%.At the same time,the tensile strength of the samples was 736.40 MPa,the yield strength was 697.53 MPa,and the elongation was 10.96%.Under the stress aging conditions of 250 MPa,the stress relaxation mechanism mainly includes grain boundary Coble creep and dislocation movement.Dislocation movement promotes the proliferation of subgrains.Coble creep makes the grain size of the matrix grow.These behaviors promote stress dissipation of the sample.At the same time,stress aging changes the morphology of precipitates,and develops composite precipitates with twin interfaces.According to the mo-lecular dynamics calculation,this characteristic microstructure is beneficial to the coordinated improvement of matrix toughness and strength.