PSI - Issue 65

A.N. Romanov / Procedia Structural Integrity 65 (2024) 200–208 A.N. Romanov / Structural Integrity Procedia 00 (2024) 000–000

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a

b

Fig.6. Changes in stress in tensile half-cycles (a) and accumulated damage from elastic deformation (b) under rigid loading of steel 22k at 2700C.

The kinetics of damage from plastic deformation (width of hysteresis loop) (a) and total damage (b) with increasing number of loading cycles calculated by criterion (11) are presented in Fig. 7. a b

Fig.7. Damage caused by reversible plastic deformation (a) and total damage (b) under rigid loading.

Thus, for conditions of intensive deformation aging, durability was calculated using the strain-kinetic criterion, in good agreement with the experimental data (Fig.5,d and Fig.7,b). The experimental results show that strain aging dramatically changes the deformation and fracture resistance of room temperature cyclically stable structural carbon steel (22k) under soft and hard loading. a b

Strain ε 0 , %

Fig.8. Fatigue curves of 22k steel under soft loading in strain (a) and hard loading in stress (b) at 270 0 C.°

Evaluation of the nature of steel behavior under soft and hard loading can be performed using the strain and force parameters of the initial half-cycle of loading. As shown in Fig.8,a, the representation of the fatigue curve of soft loading in strains ε 0 of the first (zero) half cycle of loading (black triangles) allows us to display the kinetics of deformation processes accompanying soft loading.