7B04 aluminum stress corrosion studies
|School||Kunming University of Science and Technology|
|Course||Materials Processing Engineering|
|Keywords||7B04 SCC Aluminum Sensitivity|
Aluminum is the aviation industry in the important structural materials. As technology advances, the modern aviation industry require high strength, high hardness, high corrosion resistance of the new alloy, in order to meet the new requirements of aircraft structural materials. Stress corrosion cracking (referred to as SCC) is a corrosive environment and at the same time under the action of tensile stress caused by the metal bearing capacity of the structure decreased, resulting in damage to the metal structure. Studies have shown that aluminum in the working medium has a higher susceptibility to stress corrosion. Stress corrosion make aluminum sudden failure, resulting in a catastrophic aircraft accident, therefore, stress corrosion resistance of aluminum alloy overall performance is a measure of an important indicator of the use of slow strain rate tensile stress corrosion test method 7B04 aluminum alloy Stress corrosion cracking susceptibility. Effects of temperature, corrosive media, electrochemical polarization effects on the stress corrosion susceptibility results show that with increasing temperature 7B04 aluminum alloy increased sensitivity to stress corrosion cracking; corrosive solution stronger, 7B04 aluminum alloy to stress corrosion cracking greater sensitivity; either anodic or cathodic polarization will increase 7B04 aluminum alloy stress corrosion cracking susceptibility. T7451, T7351 state 7B04 aluminum alloy to meet the requirements specified stress-life conditions, stress corrosion resistance is better, much better than the T651 peak aging condition. T651 and T7451 state 7B04 aluminum alloy were critical stress 120MPa and 300MPa, while the T7351 resistance to stress corrosion resistance state is reached very high level, no stress corrosion tendencies. Different states, different specifications of 7B04 aluminum alloy to stress corrosion fracture showed an intergranular fracture characteristics, some have secondary cracks. Russian material stress corrosion data comparison and Russia manual data, Southwest Aluminum performance aluminum production are more than 7B04 Russian standards. Obtained using fracture mechanics approach critical stress intensity factor stress corrosion cracking in corrosive media KISCC and the propagation rate da / dt and other parameters can be directly applied to component selection and design. Tests showed that the state 7B04 aluminum T651 higher sensitivity to stress corrosion. Overaged state T74 and T73 so that the maximum processing critical size increases, the relative T6 state with stress and corrosive environmental conditions, while breaking their maximum critical size defect caused by crack, the part produced destruction cycles. This guarantees that the structure in the stress (stress component assembly and their own residual stress, etc.) and the combined effect of corrosive environment to improve life.