摘要
Two kinds of Al-6.0Zn-2.0Mg-0.12Zr and Al-6.0Zn-2.0Mg-0.2Sc-0.12Zr alloy plates were prepared by ingot-metallurgy. The alloy plates with 3 mm thickness were welded by argon shield welding method,and the mechanical properties and microstructures of the two welded joints filled with Al-Mg-Sc welding wire were studied comparatively. The results show that firstly,minor Sc can raise the mechanical properties of the Al-Zn-Mg-Zr base alloy greatly. The reason for the increment is the fine grain strengthening,precipitation strengthening and the substructure strengthening caused by Al3(Sc,Zr). Secondly,η′ phase(MgZn2) and grain size in the heat-affected zone of the alloy without Sc become coarse obviously,the η′ phase(MgZn2) in the heat-affected zone of the alloy with Sc becomes coarse also,but the grain size has no visible change. Al3(Sc,Zr) particles are rather stable and can inhibit the movement of dislocation and sub-grain boundaries,overaging softening is not serious. Thirdly,adding minor Sc can raise the strength of welded joint remarkably,the tensile strength of alloy with Sc increases from 395 MPa to 447 MPa and the welding coefficient increases from 0.7 to 0.8 as well. The reason for the high strength of welded joint with Sc addition is the fine grain strengthening,precipitation strengthening and the increasing of resistance to thermal cycling softening caused by Al3(Sc,Zr).
Two kinds of AI-6.0Zn-2.0Mg-0.12Zr and AI-6.0Zn-2.0Mg-0.2Sc-0.12Zr alloy plates were prepared by ingot-metallurgy. The alloy plates with 3 mm thickness were welded by argon shield welding method, and the mechanical properties and microstructures of the two welded joints filled with AI-Mg-Sc welding wire were studied comparatively. The results show that firstly, minor Sc can raise the mechanical properties of the Al-Zn-Mg-Zr base alloy greatly. The reason for the increment is the fine grain strengthening, precipitation strengthening and the substructure strengthening caused by Al3(Sc, Zr). Secondly, η phase (MgZn2) and grain size in the heat-affected zone of the alloy without Sc become coarse obviously, the η' phase (MgZn2) in the heat-affected zone of the alloy with Sc becomes coarse also, but the grain size has no visible change. Al3(Sc, Zr) particles are rather stable and can inhibit the movement of dislocation/land sub-grain boundaries, overaging softening is not serious. Thirdly, adding minor Sc can raise the strength of welded joint remarkably, the tensile strength of alloy with Sc increases from 395 MPa to 447 MPa and the welding coefficient increases from 0.7 to 0.8 as well. The reason for the high strength of welded joint with Sc addition is the fine grain strengthening, precipitation strengthening and the increasing of resistance to thermal cycling softening caused by Al3(Sc, Zr).
出处
《中国有色金属学会会刊:英文版》
CSCD
2007年第A01期244-248,共5页
Transactions of Nonferrous Metals Society of China
基金
Project(2005CB623705) supported by the National Basic Research Program of China
关键词
铝
锌
镁
合金
焊接技术
微观结构
Al-Zn-Mg-Zr alloy
welding
Sc
microstructure
tensile properties