摘要
对自然时效态2195铝锂合金进行了不同程度(0%~10%)的预变形处理,采用180℃、初始加载应力250 MPa的应力松弛时效试验,结合室温拉伸性能测试及扫描电镜(SEM)观察,研究了预变形对应力松弛时效态2195铝锂合金显微组织和力学性能的影响。结果表明,随着预变形量的增加,合金应力松弛时效后的残余应力总体上呈先减小后增加的趋势,预变形4%的合金,其残余应力最低,因而对蠕变应变的积累更为有利。无预变形合金的应力松弛曲线表现出四阶段特征,而经过预变形的合金呈现出两阶段特征,这归因于有无预变形下合金微观组织演化的差异。应力松弛时效态合金的屈服强度和抗拉强度均随预变形量的增加而增加,无预变形应力松弛时效态合金的断后伸长率最小,而4%预变形合金的断后伸长率最大。经4%预变形后,应力松弛时效合金展现较优综合力学性能的内在原因为晶粒内部均匀分布的细小T_(1)强化相以及晶界处相对狭窄的无析出带。就断裂机制而言,未经预变形处理的应力松弛时效合金的断裂机制为沿晶断裂,而在4%和10%预变形条件下,断裂机制则分别为穿晶韧性断裂和穿晶解理断裂。
Different pre-deformations(0%-10%)were performed on the naturally aged 2195 aluminum-lithium alloy.The effect of pre-deformation on the microstructure and mechanical properties of the 2195 aluminum-lithium alloy after stress relaxation aging was studied by means of stress relaxation aging test at 180℃under initial loading stress of 250 MPa,mechanical tensile test at room temperature and scanning electron microscope observation.The results show that as the pre-deformation increases,the residual stress after stress relaxation of the alloy generally decreases and then increases.The alloy with 4%pre-deformation has the lowest residual stress,which is more conducive to the accumulation of creep strain.The stress relaxation curve of the alloy without pre-deformation shows four-stage characteristics,while that of the alloy with pre-deformation show two-stage characteristics,which is attributed to the difference in evolution of microstructure of the alloy with or without pre-deformation.The yield strength and tensile strength of the stress relaxation aged alloy increase with the increase of pre-deformation.The elongation after fracture of the stress relaxation aged alloy without pre-deformation is the smallest,while that of the stress relaxation aged alloy with 4%pre-deformation is the largest.The intrinsic reason for the superior comprehensive mechanical properties exhibited by stress relaxation aged alloy with 4%pre-deformation is the uniform distribution of small-sized T_(1)strengthening phases within the grains and the relatively narrow precipitation free zones at the grain boundaries.The fracture mechanism of stress relaxation aged alloy without pre-deformation treatment is intergranular fracture,while under 4%and 10%pre-deformation conditions,the fracture mechanism is transgranular ductile fracture and transgranular cleavage fracture,respectively.
作者
张力文
刘强
Zhang Liwen;Liu Qiang(Aerospace Manufacturing Engineering Center,Xi'an Aeronautical Polytechnic Institute,Xi'an Shaanxi 710089,China)
出处
《金属热处理》
北大核心
2025年第2期160-165,共6页
Heat Treatment of Metals
基金
西安航空职业技术学院2023年度校级重点项目(23XHZK-05)
陕西省青年创新团队项目(2023-98)。
关键词
2195铝锂合金
预变形
应力松弛时效
析出相
沉淀无析出带
2195 aluminum-lithium alloy
pre-deformation
stress relaxation aging
precipitate
precipitation free zone
