INFLUENCE OF ULTRASONIC IMPACT TREATMENT ON THE FATIGUE SAFETY COEFFICIENTS OF WELDED JOINTS OF THE STRENX 700MC STEEL

Research results of influence of the UIT (Ultrasonic Impact Treatment) on welded joints, executed on the Strenx 700MC steel, are presented in this paper. The fatigue tests of those joints were performed by rotating bending in the region of the high number of loading cycles (105 to 107) with parameters: frequency 35 Hz, cycles asymmetry factor – 1, at the ambient temperature 20 ± 2 °C. The fatigue safety coefficient was calculated before the UIT (in the original state) and after the UIT, according to four methods. An increase was recorded for the latter state: for the Goodman method of 10.45 %, for the Gerber method of 10.21 %, for the ASME method of 5.96 % and for the Soderberg method of 7.40%.