Effect of Shot Peening on Stress-Corrosion Properties and Stress Distribution in Aluminium Alloy D.T.D. 5054

Abstract

Stress-corrosion data have been obtained from shot-peened specimens cut in the short transverse direction from an aluminium-alloy extrusion to specification D.T.D. 5054. The specimens were prepared for test in three different ways, to obtain three different residual macro stress systems, typical of the conditions in which the alloy is used in service; it has been shown that, after shot peening, the stresscorrosion properties of each of the three groups of specimens have been improved to a marked extent. X-ray diffraction studies on the specimens have shown that for the particular intensity of peening employed, the resulting highly stressed compressive layer on the surface is of the order 0·006 in. thick and that all evidence of the pre-peening residual stress on the specimen surface has been obliterated. The residual stress nleasurements show that the balancing tensile stresses are distributed through the remainder of the section rather than concentrated in peak form immediately below the induced surface compression.