Study On The Microstructure And Properties Of 7050 Aluminum Alloy By Soft-contact Electromagnetic Continuous Casting

7050 Aluminum alloy is widely used in aviation and astronavigation for its good properties,such as high strength,high toughness,good hardenability etc.With the development of high performance airplane,the demanded quantity of heavy gauge thick plate of 7050 alloy increases rapidly.But the component of this alloy is so complex that it's very difficult to forming.Nowadays it has become attractive material both in domestic and abroad.Soft-contact Electromagnetic continuous casting(SEC) is a new material processing method,which combines magneto-hydrodynamics(MHD) with metallurgical engineering. SEC could clear up lots of defects such as cracks,segregations.SEC has become an important method to produce high quality alloys.The casting process and technical parameters of SEC for 120×420×(800～1000) mm 7050 aluminum alloy slabs were described in this paper.In order to analyze the as-cast microstructure and properties,a combination of metallographic microscope,scanning electronic microscope(SEM),electronic universal testing machine,electron probe microanalysis(EPMA),differential scanning calorimeter(DSC) etc.has been used.This paper studied the effect of SEC on the defects,grain size,microscopic structure,mechanical properties and the distribution of elementary composition.Meanwhile,the homogenized treatment processing of 7050 alloy was studied.It is found that:SEC can change the first stage of solidifying process,reduce the contact area and contact pressure between the melt and the crystallizer,improve the surface quality of slabs;electromagnetic stirring can uniform the microstructure and improve the mechanical properties.The homogenized processing of 7050 alloy was determined by experiments.