Effect of microstructural modification on damage tolerance of 34CrMo4 shaft steel

The research article “Effect of microstructural modification on damage tolerance of 34CrMo4 shaft steel”, co-authored by METU member Prof. Cemil Hakan Gür, has been published in Fatigue and Fracture of Engineering Materials and Structures.

Overall damage tolerances of the heat-treated 34CrMo4 steels having ferritic-pearlitic, bainitic, and tempered-martensitic microstructures were evaluated based on their threshold stress intensity factor prior to small crack propagation, fatigue strength, and fracture toughness under static loading. Kitagawa-Takahashi diagrams were constructed to determine the limiting size of small crack propagation. The micromechanical effects of carbide morphology and phase distribution on quasi-static and dynamic mechanical properties were also elaborated. Fractographic investigations were carried out on the notched fatigue test specimens to distinguish deterioration and deformation mechanism of the microstructure under reversed cyclic loads. Finally, improvements in the damage tolerance were discussed to present the advantages and disadvantages of each heat treatment procedure to minimize in-service fatigue failures.

Özcan, B., Gürer, G., & Gür, C. H. (2020). Effect of microstructural modification on damage tolerance of 34CrMo4 shaft steel. Fatigue and Fracture of Engineering Materials and Structures, 43(6), 1214-1225. doi:10.1111/ffe.13194

Article access: https://onlinelibrary.wiley.com/doi/full/10.1111/ffe.13194

Tags/Keywords:

damage tolerance, Kitagawa analysis, microstructure, short cracks, stress intensity factor

Other authors:
Özcan, B. (METU), Gürer, G. (METU)