INFLUENCE OF HARDENING BY HIGH-FREQUENCY MECHANICAL IMPACTS OF BUTT WELDED JOINTS MADE OF 15KHSND STEEL ON THEIR ATMOSPHERIC CORROSION AND FATIGUE FRACTURE RESISTANCE

摘要

We substantiate the efficiency of the high-frequency mechanical impact (HFMI) technology applied to increase the fatigue resistance of butt welded joints at the stage of production of steel structures or after their long-time operation in a zone of mild climate. The long-term influence of the atmosphere is simulated by holding the samples in a G4 chamber with controlled humidity at a temperature of 40 degrees C and an air humidity of 98% for 1200 h. The fatigue tests were carried out on four batches of butt welded joints of 15KhSND steel: in the initial state and in the state hardened by HFMI after the holding in the G4 chamber: after 2.10(6) loading cycles and holding in the G4 chamber and after 2.10(6) loading cycles, holding in the G4 chamber, and subsequent treatment by HFMI. It is experimentally established that the HFMI technology can significantly increase the cyclic durability of butt welded joints of steel structures subjected to the influence of variable loads and drops of atmospheric pressure in the zone with mild climate in the course of their operation.