摘要
以7N01-T5焊接接头为分析对象，研究了不同温度矫形对接头组织与性能的影响。结果表明，抗拉强度在250～350℃间有一谷区，400℃后维持较大值。焊缝区硬度对矫形温度不敏感，母材区与热影响区在300℃内加热时硬度下降较大，在300—350℃内上升，400℃后末明显软化。各疲劳试件均断于焊缝，大加载应力下矫形温度对接头疲劳性能影响不大。焊缝为铸态组织，晶内没有明显沉淀相析出，300℃以下的较低温度矫形对粗大相影响不明显，但在300℃会发生再结晶，350℃时熔合线处形成100μm的等轴小品粒带。对于母材区组织，室温下析出GP区和η＇相，强度与硬度较高，300℃时η’向η转变，硬度降低；350℃时有亚晶的生成；500℃时处于过时效状态，但室温下放置会自然时效析}fJGP区，故该温度下强度和硬度没有明显下降。
The changing mechanism of microstructure and properties of the 7N01- T5 aluminum alloy welded joint straightened at different temperatures was studied. Results showed that the minimum value of the tensile strength occurs after heat-straightening at the temperature between 250 ℃ and 350 ℃,and the tensile strength decreased slightly over 400 ℃. The temperature of the heat-straightening had no significant effect on the hardness of the weld,while its impact on the base metal and HAZ was much greater. The hardness of BM and HAZ heated descended below 300 ℃,then ascended slightly between 300 ℃ and 350 ℃,and remained stable over 400 ℃. The fatigue crack initiated at the weld and heat-straightening at high temperature makes fatigue properties worse during the fatigue experiment. There were no obvious precipitates in weld and the temperature below 300 ℃ had no significant effect on the evolution of coarse second phases,while it recrystallized at 300℃ in the weld,which formed the equiaxed grain zone with the size of 100 μm. As to the base metal with high strength and hardness at room temperature,it precipitated the second phase of GP and η',but its hardness descended at 300 ℃ because of the phase transition from η' to η.At 350 ℃,subgrains were formed in the base metal and the base metal was over-aging at 500 ℃,but its strength and hardness had no obvious decease as the result of precipitation of GP in natural aging at the room temperature.
出处
《焊接》
北大核心
2016年第5期49-52,56,共5页
Welding & Joining
关键词
7N01铝合金
焊接接头
矫形温度
力学性能
微观组织
7N01 aluminum alloy
welding joint
temperature of heat-straightening
mechanical properties
microstructure
