Comparison of Residual Stress Measurements Conducted by X-ray Stress Analysis and Incremental Hole Drilling Method

The level of residual stresses is of great importance for many applications. In this work, the two established residual stress analysis methods x-ray stress analysis and incremental hole-drilling combined with electronic speckle pattern interferometry are compared. Each stress analysis method has its specific limitations. Furthermore, the residual stress state of a material is influenced by its processing history. To compare both methods, aluminum-based specimens (AlCu6Mn, AlZn5.5MgCu) with different processing histories were investigated. Measurements with both methods were conducted on the same specimens and on the same measurement spots. Highest stress levels were found in the mechanically machined specimen, while heat treatment via tempering or deposition welding shows reduced stress levels inside of the specimens. In case of cold spraying, the stresses in the feedstock material are considered negligible. In contrast, cold-spray coatings deposited on construction steel substrate exhibited tensile stresses, which relax over time at room temperature.