Study On Creep Crack Growth And Damage Of 2219 Aluminum Alloy

Aluminum alloy is widely utilized in plenty of fields because of its lightweight.As the development of aerospace engineering,researchers pay more attention to the research about high temperature properties of aluminum alloy.And creep crack growth is one of the most important properties.Traditional two-dimensional observation methods can be utilized to obtain the information of creep crack growth.However,some three-dimensional information can’t be obtained via these two-dimensional methods.In this work,we studied the behavior of creep crack growth and utilize synchrotron radiation X-ray computed tomography to research the tip of creep crack.We utilized direct current potential method and some other methods to research the effect of creep crack growth which is impacted by out-of-plane constraint.The research results indicate that the inoculation period becomes shorter and opening point becomes earlier as well as the creep crack growth rate increases when the out-of-plane constraint is improved.In the correlation with creep crack growth rate,the modified J integral C* can describe the stress field at the crack tip better as the level of out-of-plane restraint increases.In the low C* area,the outof-plane constraint has less influence on the creep crack growth.But in the high C* area,the out-of-plane constraint has a greater influence on the creep crack growth.The effect of out-ofplane constraint on creep crack growth rate is related to the creep.When the out-of-plane constraint is small,the triaxial stress of the material is reduced and the specimen is more likely to creep which causes the creep crack growth to require more energy and reduce the rate.The synchrotron radiation X-ray computed tomography technology was used to research the crack tip.The reconstruction results show that there are a large number of small damage near the crack tip.The nucleation and growth of holes promote the propagation of the main crack,and there is a certain angle between the distribution of holes and the propagation direction of the main crack.The crack length at the center of the thickness direction is longer than that at the surface of the specimen.And the number and volume of holes are also different.The effect of stress and creep crack propagation time on creep crack propagation is similar.With the increase of stress and creep crack propagation time,the length and volume of the main crack,as well as the number and volume of micro-cracks and holes increase.