In the present study the objective was to study the interrelationship between hardness, electrical conductivity and residual stresses developed due to heat-treatment in 2014 aluminum alloy used extensively in aircraft industry. The pieces cut from the 2014 bar stock were solutionised and then later subjected to artificial aging treatment to produce the systematic variation in mechanical properties.

Material characterization in terms of hardness, electrical conductivity and residual stresses was undertaken and documented. Electrical conductivity was measured using a probe type portable instrument working on eddy current principle. Surface residual stress analysis was conducted by using a stress analyzer working on XRD principle. The sin2 technique, commonly employed to measure residual stresses was applied to monitor the structural changes in aged aluminum alloy. The experimental data so obtained were then analyzed.

It was found that the X-ray residual stress measurements could reliably predict the degree of aging in the aluminum alloy component under consideration. Further the trends observed in the values of the residual stresses could be completely rationalized on the basis of the interaction of the coherent and the incoherent precipitates with the elastic stress fields generated during heat-treatment on a microstructural scale. The independent measurements of the electrical conductivity and the hardness made in this work lend a convincing support to the explanation.

A salient feature of the present work was the relatively accurate measurements of the residual stresses. It is hoped that the methodology followed and the results obtained in this work should prove useful in future, in taking our understanding of the residual stresses and the aging phenomenon in aluminum alloys one step ahead.