Abstract
1. The results show that the increase of the coefficient of load cycle asymmetry from 0.1 to 0.95 for the 15Kh2MFA (I) and 15Kh2MFA (II) steels at 293°K leads to a large reduction of the rate of fatigue crack propagation, if the results are presented in the dl/dN-Kmax coordinates. 2. In the examined range R(0.1–0.93), 15Kh2MFA (II) steel is characterized by unstable fatigue crack propagation which precedes final fracture of the specimen. 3. The cyclic fracture toughness (Kfc1)min of 15Kh2MFA (I) steel at 293°K does not depend, in the given scatter range, on load cycle asymmetry for the value of R varying from 0.1 to 1 and is equal to K Q max . For 15Kh2MFA (II) steel, the value of (Kfc1)min remains constant up to R=0.87. With a further increase of the coefficient of cycle asymmetry, the value of (Kfc1)min increases linearly to the level of KIc. 4. An increase of the coefficient of load cycle asymmetry from 0.1 to 0.95 is accompanied by the increase of threshold SIF Kth for the 15Kh2MFA (I) and 15Kh2MFA (II) steels. The value of Kth for 15Kh2MFA (II) steel at R≥0.87 coincides with the critical SIF (Kfc1)min. 5. An increase of the coefficient of load cycle asymmetry from zero to one at the identical values of Kmax reduces the critical rate of FCP in the 15Kh2MFA (I) and 15Kh2MFA (II) steels and at R=0.87 the rate of FCP in 15Kh2MFA (II) steel is equal to 10−10 m/cycle. 6. The rate of reduction of fracture toughness in cyclic loading depends greatly on cycle asymmetry. For example, while at R=0.1 the reduction of the fracture toughness of 15Kh2MFA (II) steel from KIc to (Kfc1)min takes place approximately within 4.104 cycles, at R=0.83–0.85 the identical reduction takes place within 3.106 cycles. 7. The results of the investigations of the cracking resistance of the 15Kh2MFA (I) and 15Kh2MFA (II) steels were used to proposean approach to predicting the effect of load cycle asymmetry on fracture toughness in cyclic loading.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
