Research On Residual Stress Detection Technology Of 5A06 Aluminum Alloy Welded Joints

Welding process of aluminum alloy has becoming an important forming technology for vital structure in satellite.Residual stress produced by thermodynamic activity in course of welding process had a negative influence on stability of welded components and reliability of aerospace products.Precise nondestructive measurement of residual stress can provide reassuring evidence for optimizing welding process and reducing harm to the components of aerospace produce,this is magnificent to ensure the stability and service life of satellite.Researching object in this paper is a VPPA welding product which is made of 5A06 aluminum alloy rolled plate widely used in manufacturing satellite structure.Residual stress measurement for the mentioned object above takes X-ray diffraction method.At present,the research about location of heat-affected zone of VPPA,difference of diffraction peak position,optimization of measuring parameters are not thoroughgoing yet,and detailed measuring process are not available,especially to the aerospace product.In order to solve the above problems,this paper carried out the following research: the determination and optimization of X ray diffraction residual stress testing parameters of force test,and evaluate the accuracy of test results;analysis of diffraction peak position difference and data postprocessing;partition detection method of welding residual;determination of the position of the heat affected zone location and analysis of the influence of the microscopic state of test precision;analysis of influence of surface condition on test precision.By researching and experiment,some results achieved: a standard sample system which can be used for the accuracy evaluation and intercomparison of residual stress detection is established,and a set of testing parameters suitable for stress detection of 5A06 aluminum alloy is optimized,which is suitable for stress detection of welded joints,location of heat-affected zone by X-ray diffraction peak and peak position features,and the influence of various test factors on the test results of residual stress is discussed.During the test of welding structure,it was found that: increased measuring tolerance caused by difference in crystalline structure between heat-affected zone and base metal,decreased measuring accuracy by aluminum-coating.the numerical results achieved with X ray diffraction method conform to the theoretical expectation and the electronic speckle test results when the pre treated welding structure is tested.The detection process is preliminarily planned: first,the surface of the welded joints is regulated;then the location of the heat affected zone and the regional boundary is determined,and the stress detection is carried out on the weld area and the base area near heat affected zone;finally,the stress distribution of the welded joint is deduced from the test results.