Exploration of the high-cycle fatigue properties of Al-rich interstitial free steels stabilized by Ti and Nb

• Published in: International journal of fatigue 2025-02, Vol.191, p.108674, Article 108674
• Main Authors: Guennec, Benjamin, Tamboli, Rameez R., Nagano, Kentaro, Kinoshita, Takahiro, Horikawa, Noriyo, Fujiwara, Hiroshi, Bhattacharya, Basudev, Dey, Suhash R.
• Format: Article
• Language: English
• Subjects: Cyclic stress–strain; Dislocation observation; Early fatigue crack propagation; High-cycle fatigue; Interstitial-free steel
• ISSN: 0142-1123
• DOI: 10.1016/j.ijfatigue.2024.108674

•Fatigue properties of novel Al-rich interstitial-free steels have been studied.•Al-rich IFHS grade has a larger fatigue endurance than conventional IFHS.•Propagation of small cracks are influenced by lattice rotation, including subgrain.•Subgrain formation is enhanced in Al-rich IFHS in respect with conventional grade.•Soluble Al alloying element should have facilitated cross-slip mechanism. The addition of Al element is a promising method to enhance the deep drawing ability of interstitial free steels, since it favors a strong normal direction fiber texture. However, the scarcity of experimental results on the mechanical properties of such Al-rich interstitial free grades is detrimental to its potential applications in various industrial fields. In the present work, the high-cycle fatigue properties of Al-rich interstitial-free and high-strength interstitial-free steels have been investigated. Al-rich interstitial free steel presents the lowest fatigue endurance at 107 cycles among the materials investigated (158 MPa), mainly driven by its coarse microstructure. Furthermore, its lower Mn concentration in comparison with high-strength interstitial-free grades provokes grain shape change mechanism, resulting in the occurrence of a transient intergranular fatigue crack propagation feature. Despite their similar microstructures and monotonic strengths, Al-rich high-strength interstitial-free grade reveals a fatigue endurance at 107 cycles of 273 MPa, significantly larger than its conventional Al concentration counterpart (i.e., value of 233 MPa). This gap mainly stems from the generation of extended dislocation substructures in Al-rich grade, which tends to prevent early fatigue crack propagation.