| Autor: |
Pustovoit, V. N., Grishin, S. A., Dolgachev, Yu. V., Duka, V. V. |
| Zdroj: |
Steel in Translation; Feb2022, Vol. 52 Issue 2, p140-144, 5p |
| Abstrakt: |
In this paper, we present results of fatigue tests of a natural steel composite material for cyclic bending by a zero-loading cycle. Natural ferrite-martensitic composite (NFMC) has a structure of alternating layers of ductile ferrite and strong martensite, which causes a special mechanism of crack retardation under loading. The zero-loading cycle assumes the presence of tensile forces directed only in one direction, which makes it possible to avoid hardening of the crack edges during its growth. Using the obtained data on the kinetics of the development of a fatigue crack and the rate of its growth, a diagram of fatigue failure was constructed depending on the number of vibration cycles. Test results of samples from steel of one chemical composition are compared. In one case, a traditional heat treatment was carried out on the structure of tempering sorbitol. In the other case, a layered structure of the ferrite-martensite composite was obtained by quenching the initial line ferrite-pearlite structure from the intercritical temperature range. These materials had the same hardness, but the difference in structural organization determined the advantage of steel with the NFMC structure in terms of fracture resistance under cyclic loading. When a crack approaches the martensite-ferrite interface, delamination occurs in the ferrite due to tensile stresses parallel to the crack plane. The crack growth stops until additional energy for the formation of a new crack under conditions close to the uniaxial stress state is supplied. A technique for determining the characteristics of crack growth kinetics under fatigue loading, which is recommended for testing steels and alloys under conditions of cyclic load changes, is presented. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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