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.

中文翻译：

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Ti 和 Nb 稳定的富铝无间隙钢的高周疲劳性能探索


添加 Al 元素是增强无间隙钢深冲能力的一种很有前途的方法，因为它有利于强大的法向纤维纹理。然而，关于这种富铝无间隙等级的机械性能的实验结果的稀缺不利于其在各种工业领域的潜在应用。在本工作中，研究了富铝无间隙钢和高强度无间隙钢的高周疲劳性能。在所研究的材料中，富铝无间隙钢在 107 次循环 （158 MPa） 时的疲劳耐久性最低，这主要是由其粗大的微观结构驱动的。此外，与高强度无间隙等级相比，其较低的 Mn 浓度会引起晶形变化机制，从而导致瞬态晶间疲劳裂纹扩展特征的发生。尽管它们的微观结构和单调强度相似，但富铝高强度无间隙牌号在 273 MPa 的 107 次循环中显示出疲劳耐久性，明显大于其传统的铝浓度对应品（即 233 MPa）。这种差距主要源于富铝牌号中扩展位错子结构的产生，这往往会阻止早期疲劳裂纹扩展。