ABSTRACT
This chapter focuses on using classic ultrasound defectoscope for identification of internal residual stress after machining material steel C45, which is a less economically demanding method of measuring residual stress. The deformation are formed in internal layers during machining, which influences crystal lattice and do not disappear even after the discontinuation of external force effect on machining material. There are three factors to the forming residual stress: Plastic deformation, Phase transition, Local thermal heating. Residual stress is formed by elastic plastic deformation in the cutting zone. Residual stress or internal stresses are stresses in the internal layer of material, which remains in material even after the ceasing of force or load and they are closely related to plastic deformation. Ultrasonic measuring of residual stresses was used for welded luminum plates. The ultrasonic stress measurement is accomplished by using longitudinal critically refracted waves which are propagated parallel to the surface within an effective depth.
