Analysis of Fatigue Crack Paths in Cold Drawn Pearlitic Steel
Abstract
:1. Introduction
2. Experimental Method
3. Experimental Results
3.1. Microstructural Analysis
3.2. Fractographic Analysis
4. Discussion
5. Conclusions
- (i)
- From the microscopic point of view, fatigue cracks in pearlitic steel develop exhibiting micro-plastic tearing. This fact is consistent with an evidence of cyclic micro-damage and crack advance produced by a mechanism of plastic strain concentration. The cold drawn wire exhibits a pattern resembling micro-tearing, these events being of lower size and more curved aspect than those associated with the hot rolled bar.
- (ii)
- Cracking paths produced by fatigue (cyclic) loading develop in the form of trans-colonial advance and tending to fracture a certain proportion of pearlitic lamellae in the corresponding colony of pearlite. As a matter of fact, fatigue crack propagation can be classified as tortuous, with certain quantity of micro-discontinuities, branchings (frequently, bifurcations also appear), as well as local deflections, thereby producing a sort of roughness (at the microstructural level) with associated non-uniform crack opening displacement distribution.
- (iii)
- The fractographic analysis of the cracked surface produced by fatigue fracture in the cold drawn pearlitic wire exhibits an appearance consisting of micro-roughness. In this case, the total fractured surface (including the afore-said micro-discontinuities, branchings, bifurcations and local deflections) is greater than in the case of the hot rolled bar (base material). The reason is that the deflections in the fatigue crack path are more frequent and with greater angle in the cold drawn wire than in the hot rolled bar. The increase of the stress intensity factor (SIF) range, ∆K, also produces higher micro-roughness in the fracture surface.
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Toribio, J.; González, B.; Matos, J.-C. Analysis of Fatigue Crack Paths in Cold Drawn Pearlitic Steel. Materials 2015, 8, 7439-7446. https://doi.org/10.3390/ma8115388
Toribio J, González B, Matos J-C. Analysis of Fatigue Crack Paths in Cold Drawn Pearlitic Steel. Materials. 2015; 8(11):7439-7446. https://doi.org/10.3390/ma8115388
Chicago/Turabian StyleToribio, Jesús, Beatriz González, and Juan-Carlos Matos. 2015. "Analysis of Fatigue Crack Paths in Cold Drawn Pearlitic Steel" Materials 8, no. 11: 7439-7446. https://doi.org/10.3390/ma8115388