(1. 中南大学 粉末冶金国家重点实验室,长沙 410083; 2. 江苏豪然喷射成形合金有限公司,镇江 212009)
摘 要: 以喷射成形7055-T6铝合金为对象,借助万能力学试验机、电化学工作站、光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)等手段研究热锻对挤压合金显微组织与性能的影响。结果表明:挤压合金的纵向抗拉强度为705 MPa,屈服强度为665 MPa,断口形貌表现为沿晶断裂,而锻造后合金的抗拉强度、屈服强度分别下降了33 MPa和34 MPa,但伸长率、硬度和导电率均有所上升,断口形貌表现为韧性断裂;挤压合金晶粒较均匀,组织有方向性,但热锻后合金部分晶粒长大合并,部分晶粒破碎;合金晶界析出相中的主要元素含量均比基体高,且热锻后合金晶界析出相中的Mg、Zn元素含量降低,Cu元素含量升高;合金经峰值时效后,晶内GP区和η′析出相为主,晶界析出相近似连续分布,导致合金耐蚀性不好;锻造后晶界和晶内析出相均长大粗化,使得合金强度下降,耐蚀性提高。
关键字: 喷射成形7055-T6铝合金;锻造态;挤压态;显微组织;性能
(1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. Jiangsu Haoran Spray Forming Alloy Co., Ltd., Zhenjiang 212009, China)
Abstract:High strength 7055-T6 aluminum alloys were produced by spray forming. The microstructures and properties of alloy after forging and extrusion were investigated using tensile test, electrochemical workstation, optical microscope(OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The results indicate that the tensile strength of the extruded alloy can reach 705 MPa, the yield strength can reach to 665 MPa, and the extruded alloys exhibit an intergranular fracture, the tensile strength and yield strength of the forged alloy decrease by 33 MPa and 37 MPa, respectively, but the elongation, electrical conductivity and hardness all have increased, and the forged alloys exhibit a ductile fracture. The extruded alloys feature fine and homogeneous, the grains are elongated along extrusion, but some grains of forged alloys are broken, and some grains grow up; and the grain boundary precipitates of extruded alloys continuous distribution, the distribution of precipitated phases in grain boundary is dispersive and homogeneous, which leads to a bad corrosion resistance; the precipitated phases of forged alloys have coarsened, which reduce the strength properties but increase the corrosion–resistance.
Key words: spray forming 7055-T6 aluminum alloy; as-forged; as-extruded; microstructure; property