THE EFFECT OF INTERMEDIATE CONDITIONING IN THE PROCESS OF STEEL FATIGUE ON STEEL DURABILITY,

Specimens of carbon steel 40 0.37-0.45 carbon and chromium stainless steel 2Kh13 0.16-0.23 carbon, 12-14 chromium were subjected to cyclic stresses 10-15 higher than their fatigue strength 29.5-30.6 and 33.7 kgmm2, respectively for a number of cycles equal to 75 to 95 of the number of cycles at failure. After that, the stress was lowered to 75-90 of the fatigue strength for 5,000,000 cycles training period and then returned to the initial magnitude, which was maintained up to failure. The training significantly improved the fatigue life of both steels. For instance, while untrained specimens of steel 40 under stresses 10 or 15 higher than fatigue strength failed after 192,650-353,500 or 230,650-239,950 cycles, respectively, the trained specimens failed after 254,200-750,600 or 259,400-352,200 cycles 2Kh13 steel exhibited similar behavior. Post-training annealing of 2Kh13 steel at 650C for 2 hr in argon produced no additional beneficial effect. Author