Process and Performance of 7075 Aluminum Alloy Friction Stir Welding
In order to explore the relationship between welding speed and the process or performance of 7075 alumi-num alloy friction stir welding,friction stir welding(FSW)was carried out on 7075 aluminum alloy under the rotation speed of 300 r/min and welding speed of 100 mm/min,120 mm/min and 150 mm/min,respectively.Effects of differ-ent welding speeds on microstructure,mechanical properties and corrosion resistance of welded joints were analyzed by means of optical microscopes,universal testing machines,scanning electron microscopes,contact angle measurement and electrochemical workstations.The results indicate that with the increase of welding speed,the grain size of stir zone(SZ)and thermo mechanical affected zone(TMAZ)becomes smaller.Under the constant welding process parameters,the grain size of TMAZ on the advancing side is smaller than that of one on the retreating side.With weld-ing speed rising from 100 mm/min to 150 mm/min,the tensile strength and elongation of the joint is firstly increased and then decreased,and tensile strength reaches the maximum of 382.7 MPa at 120 mm/min,which is 70%of the base metal(550 MPa).As the welding speed increases,the contact angle of the stir zone presents a trend of increasing firstly and then decreasing,and the corrosion resistance also shows a similar trend.Under the process parameters of 300 r/min and 120 mm/min,the corrosion resistance is desirable,where the contact angle and corrosion potential of the stir zone reach maximum values,which are 87.996°and-0.74 V,respectively,and self corrosion current density of 4.0×10-6 A/cm2 can be obtained.
NETL
NSTL
万方数据
