Fatigue Behavior of 4340 Steel at Room and Elevated Temperatures: Correlating Fatigue and Tensile Testing Data

Ziraki, Sahar; Moghaddam Kia, Amir; Ebrahimi, Ramin

doi:10.22068/ijmse.4368

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‎ 10.22068/ijmse.4368

Fatigue Behavior of 4340 Steel at Room and Elevated Temperatures: Correlating Fatigue and Tensile Testing Data

Sahar Ziraki

, Amir Moghaddam Kia

, Ramin Ebrahimi

Abstract: (706 Views)

In this study, an existing approach for estimating fatigue life using tensile data was extended and applied to 4340 steel under different temperature. The S-N and strain-life curves were plotted at 25, 200, and 350 ˚C. The Basquin and Coffin-Manson equation constants were determined based on the corrected true fracture stress and strain values. Moreover, the b constants were approximated as -0.065, -0.072, and -0.073 at 25, 200, and 350 ˚C, respectively. This was achieved by setting the alternating stress equal to the fatigue limit in an infinite number of cycles when b leveled off. The transition fatigue life of 1000 cycles was considered for 4340 steel to determine the c constants, which were determined to be -0.69, -0.7, and -0.699, at 25, 200, and 350 ˚C, respectively and the strain-life curves were plotted. Comparison of S-N curves obtained from both fatigue and tensile data revealed strong agreement, indicating that the tensile test is a simple and cost-effective method capable of providing a quick estimate of high- and low-cycle fatigue behavior and serving as a suitable alternative to conventional fatigue testing.

Keywords: S-N curve, Fatigue test, Tensile test, 4340 steel