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Integrity of surfaces finished with ultrasonic burnishing

Ultrasonic burnishing is a relatively new method used for finishing workpieces to produce good surface quality. Ultrasonic burnishing does not involve material removal from the surface of the workpiece. However, the method has a significant deforming effect on the material, especially close to the surface, which is why it is vital to know the effect of the method to residual stresses in the material. This study looks at the residual stresses produced in two 34CrNiMo6-M tempering steel qualities of different hardness. The magnitude of stresses is examined using the hole drilling method. The hardness and surface quality of the finished workpiece are measured. The results show that the ultrasonic burnishing not only treats material on the surface efficiently but also deforms the material deeper, producing compressive residual stresses in the workpiece. The hardness increases after finishing and surface quality improves significantly. The roundness of the workpiece is improved and dimensional changes are minor.