Application of laser interferometry to the choice of processing modes by the criterion of the residual stress level

Abstract

Optimization of the modes of technological processing aimed at reduction or redistribution of residual stresses requires the use of modern and reliable methods of control. The method of laser interferometry leads to minor damages which are considered acceptable or can be easily removed. It is possible to use the method in industrial conditions of the workshops. Unlike physical methods, which have restrictions imposed on the classes and characteristics of materials in terms of structure, magnetic properties, and hardness, the method of laser interferometry exhibits a universal character. The method allows data saving in a digital format on speckle interferograms, thus providing a possibility of the traceability of measurement stages, expert comparison and reliable reporting. Laser interferometry provides determination of the absolute values of stresses with the error of the yield point measurement below 10%. The method can be successfully used to control the stress state in the production of critical welded structures from aluminum alloys, which are subject to stringent requirements for dimensional stability, accuracy and reliability. The technology of manufacturing the above welded structures usually includes vibration treatment, combined with the arc welding process. This technology, unlike heat treatment, is rather efficient, environmentally friendly, and low energy consumption process. Optimization of the technology plays a key role in the industrial implementation and can significantly reduce the economic costs of subsequent machining. The method of laser interferometry provides effective determination of the optimal technological mode by the parameter of residual post-welding stresses, as well as determination of the degree of the reduction of those stresses compared to the case without concomitant vibration treatment.