UDC 539.421.3 FATIGUE CRACK PROPAGATION MODELING OF HYDROGENATING HIGH-STRENGTH STEELS © A.N. Romanov DSc, professor, Blagonravov Mechanical Engineering Research Institute of RAS, Moscow, Russia P.V. Tarakanov Post-graduate student, Bauman Moscow State Technical University, Moscow, Russia G.V. Shashurin PhD, Blagonravov Mechanical Engineering Research Institute of RAS, Moscow, Russia Yu. <...> V. Berchun Bauman Moscow State Technical University, Moscow, Russia L.A. Rezchikova Bauman Moscow State Technical University, Moscow, Russia P.S. Sokol’nikov Bauman Moscow State Technical University, Moscow, Russia Abstract. <...> The paper presents an empirically-specified model of crack propagation in hydrogenating structure components made from high-strength steels under cycling. <...> The developed model is used to define the crack growth rate in the structure components under consideration. <...> Obtained results for high-strength steel AISI 4340 are represented in diagram L(t) as the appearing special zones. <...> Each structure, apparently, may have different metallurgical defects (e.g. cracks of L0 initial length). <...> An aggressive hydrogen environment inf luence is supposed to accelerate a fatigue fracture process precipitation in the structure component containing de fects [3]. <...> The paper describes the central crack kinetics of L length in the infinite plate [4] in the specimen made from the high-strength steels using two different models, i.e. hydrogen cracking (HC) model and fatigue cracking (FC) one. <...> Authors suppose that inf luence of cycling in combination with hydrogen environment leads to appearing some features in crack kinetics. <...> Crack kinetics is described till the unstable cracking (UC) comes out to be a prevailing fracture mechanism. <...> Suppose that either the aggressive hydrogen environment inf luence or the plastic strain accumulation, because of cycling, initiate a local fracture process in the considered structure component. <...> This means that the crack growth rate due to simultaneous action of hydrogen and cycling is described as follows [5] (1) where and are the crack growth time from li li+ai caused by the hydrogen embrittlement under constress far from the crack. <...> The life of a structure component t* to stant loading and by the fatigue, respectively [X] and [Y] are mechanical and environment <...>