Effect of loading-cycle asymmetry on the crack resistance of structural alloys

Autor: P. V. Yasnii, M. V. Avanesov, V. T. Kaplunenko, G. P. Karzov, B. T. Timofeev, V. V. Pokrovskii
Rok vydání: 1982
Předmět:
Zdroj: Strength of Materials. 14:1456-1461
ISSN: 1573-9325
0039-2316
Popis: 1. Steels 15Kh2NMFA and 15Kh2MFA are characterized by a reduction in FCR on the moderate-amplitude section of the fatigue curve with an increase in positive values of the cycle asymmetry coefficient, given the same values of Kmax, at room temperature. 2. The nature of the effect of the compressive part of the load cycle on crack growth rate depends on the material and test conditions. Thus, for high-strength steel 15Kh3MA in the temperature range 213–293°K, FCR is the same in symmetrical and nonzero cycles. For steels of moderate strength (15Kh2NMFA), the compressive part of the load cycle has no effect on FCR at low temperatures (183–213°K), but the FCR is 1.5–2 times greater at R = −1 than at R = 0 when the temperature is increased to 293°K. 3. Whereas steels 10GN2MFA and 15G2AFDps are characterized by a more rapid decrease in fracture toughness in symmetrical loading than with a nonzero cycle at 83 and 133°K, for steel 15Kh2NMFA an increase in R from −1 to 0.4 has no significant effect on the relation Kfci-N. 4. The fatigue fracture toughness Kfc1 of steels 15Kh3MA, 15Kh2MFA, and 15Kh2NMFA increases with an increase in positive values of the cycle asymmetry coefficients. For steel 15Kh2NMFA in the range 183–213°K and for steel 15Kh3MA at 153°K, fracture toughness is roughly the same under symmetrical and nonzero loading conditions. 5. For steel 15Kh2NMFA at 183 and 213°K, the critical SIF corresponding to final fracture is not sensitive to a change in the cycle asymmetry coefficient when R=-1–0.4.
Databáze: OpenAIRE
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