Thermal Processing Of 2519 Aluminum Alloy Hot-rolled Sheet Resistance To Stress Corrosion Sensitivity

The main advantage of 2519 aluminum alloy is its high strength to weight ratio and therefore it is considered as a good choice for aviation and shipping industry. However, these applications may be restricted by poor characteristics such as resistance to stress corrosion cracking (SCC). To improve the mechanical properties and the resistance of stress corrosion cracking of 2519 aluminum alloy, the hot rolling process and heat treatment of 2519 aluminum alloy were investigated.The simulation of hot rolling test was performed by means of Gleeble-1500, the test results shown that it is proper for the first rolling temperature between 480 C and 500 C. The resistance of SCC of 2519 aluminum alloy was evaluated with parameters such as K0 and K . The influence of residual stress on stress corrosion cracking was studied. The relation between the electrochemical behavior and the stress corrosion cracking was also studied. In addition, fractography of the typical failed sample was conducted with a KYKY-Amary 2800 Scanning Electron Microscope (SEM). The test results indicated:1) It is reasonable that the solution temperature of 2519 A A is 530 C, holding time is 30min.2) The 2519-T8 aluminum alloy have the highest of the resistance of SCC, and it has a better mechanical properties.3) The T6 have the highest strength and elongation but lowest resistance of SCC.4) The resistance of SCC with 180 C overaging temper (T8) is better than that of 145 C overaging.5) The Duplex Quench plays an important role on the mechanical properties of 2519 AA, but have no influence on the resistance of SCC.6) There is a close relation between the electrochemical behavior of 2519 AA and the resistance of SCC of 2519 AA, the larger the polarization resistance, the better the SCC resistance.7) Under the condition of room temperature, experiment data demonstrate that the intergranular corrosion velocity of 2519 A A in solution 3.5%NaCl+l%HCl is expressed as an exponent function. v=v0+a,exp(- (t-t0)/bi) + azexp(-(t-t0)/ b2)The intergranular corrosion velocity is larger in large deformation degree than in small deformation degree.8) As a result of the influence of corrosion product, the stress state will be changed in the system of stress corrosion, therefore, the relation between the residual stress and the stress corrosion is not linear.