Influence of preliminary cyclic loading on the resistance to failure of 16G2AF low-alloy steel

1. Preliminary loading of 16G2AF steel has a marked influence on its resistance to brittle fracture. The character of this influence is determined by the stage of preceding cyclic loading. The maximum degree of embrittlement (a 10–20°C increase in T50) is observed after loading to a number of cycles of\(\bar N\)=10% and more of the expected life, which is significantly (by two or four times) less than for low-carbon steel under similar cyclic loading conditions. 2. The intensity of the decrease in the specific work for the originaoand propagationap of a ductile crack after cyclic loading at normal temperature depends upon the amplitude of the stresses andap decreases steadily over the whole investigated range of number of load cycles. 3. As the result of preliminary cyclic loading the resistance of the steel to brittle fracture decreases despite the presence in the material of individual zones of local plastic deformation causing the appearance in the brittle zones of the fractures of areas of a ductile constituent. This is related primarily to the occurrence in the basic volume of the material of strain aging.