【摘要】 研究了热处理对7A04铝合金力学性能的影响.结果表明,直径60 mm的7A04铝合金棒材在200℃电流直接加热回归后再时效,从心部到表层的拉伸强度为620-640 MPa,延伸率均匀一致;在3%NaCl+0.5%H₂O₂水溶液介质中和375 MPa应力下的应力腐蚀断裂时间大于30 d,而辐射式加热回归的为575 MPa,延伸率从心部至表层表现极不均匀,应力腐蚀断裂时间只有19 d.电流直接加热实现了直径60 mm 7A04铝合金大截面棒材的快速均匀回归,再时效获得了最弥散的晶内析出粒子和尺寸及间距较大的晶界析出相,使合金在保持T6状态拉伸强度的同时,具有优良的抗应力腐蚀性能.更多还原

【Abstract】 The effect of retrogression heating on the mechanical properties of 7A04 alloy with large cross section was investigated.The results showed that when retrogressed by electrical current heating at 200℃the tensile strength in re-aged 7A04 alloy extrusion bar of 60 mm in diameter reached 620- 640 MPa and a uniform elongation appeared from central part to surface layer of the sample while the fracture time in test of resistance to stress corrosion under a load stress of 375MPa in 3%NaCl+0.5%H₂O₂ corrosion solution was greater than 30 d.The tensile strength in samples retrogressed by panel heating was only 575MPa,and a nonuniform elongation was exhibited on the cross section.The sample retrogressed by panel heating only standed for 19 days under same condition.It is suggested that electric current heating accomplishes rapid uniform retrogression in extrusion bar of 60 mm in diameter of 7A04 alloy, the most dispersoid particles in grain interior and coarse and large spacing particles in grain boundary are precipitated,and consequently both an excellent resistance to stress corrosion and a T6 tempered tensile strength can be obtained.更多还原