含Sr的7085铝合金挤压材的各向断裂韧性  

Anisotropy of Fracture Toughness for 7085 Al Alloy Extrusions Containing Strontium

作　　者：蒋伟[1] 许晓静[1] 邓平安[1] 吴瑶[1] 孙良省 

机构地区：[1]江苏大学先进制造与现代装备技术工程研究院,江苏镇江212013

出　　处：《热加工工艺》2014年第12期87-89,95,共4页Hot Working Technology

基　　金：江苏省工业科技支撑计划项目(BE2008118);江苏大学优秀青年学术骨干培育专项基金(1211110001)资助;江苏省高校研究生科研创新计划项目(CXLX110563)

摘　　要：采用断裂韧性试验和显微观察研究了含Sr7085铝合金挤压材经固溶、预应变及时效处理后在平行(R-L)和垂直于(L-R)挤压方向上的断裂韧性与微观组织之间的联系。结果表明:7085铝合金挤压材的组织与断裂韧性存在着明显的方向性。在R-L方向其组织沿挤压方向呈带状分布,断裂韧性(Kq)值为25.76 MPa·m1/2;而在L-R方向其组织无明显带状特征,断裂韧性(Kq)为41.33 MPa·m1/2。R-L向裂纹沿着呈带状分布的细小晶粒的晶界启裂,晶界强度低;LR向裂纹穿过晶粒或沿着较大晶界启裂,强度高。细小晶粒带仅出现在挤压方向,其形成与合金中沿挤压方向呈条(带)状分布的粗大不(难)溶第二相粒子诱导的再结晶有关。7085 aluminum alloy extrusions containing strontium was subjected to solid solution treatment, prestrain and ageing treatment. The anisotropy of fracture toughness and its relationship with the microstructure of as-treated 7085 aluminum alloy extrusions were studied by using fracture toughness testing and microstructure observations. The fracture toughness testing shows that the extrusions present considerable anisotropy in fracture toughness （Kq）, with banded microstructure diswibutes along the extrusion orientation and the Kq value of25.76MPa·m^1/2 in R-L orientation （paralleling to extrusion orientation）, but 41.33 MPa ·m^1/2 in L-R orientation （perpendicular to extrusion orientation） and without banded microstructure distribution obviously. The microstructure observations show that low Kq value in R-L orientation is caused by crack starting along the fine-grain strip boundary, which has a low strength, while the high Kq value in the L-R orientation crack starting through grains and along coarse-grain boundary, which has high strength. The fine-grain strip presented only in L-R orientation, and its formation is believed to be due to the recrystallization induced by coarse second phases which distributes in paralleling with R-L orientation.

关 键 词：7085铝合金 挤压材 断裂韧性 各向异性 

分 类 号：TG146.2[一般工业技术—材料科学与工程]