A.nouri, Sh.kheirandish, H. Saghafian,
Volume 5, Issue 4 (12-2008)
Abstract
Abstract: In the current work, the strain hardening behavior of dual-phase steels with different silicon content (0.34-
2.26 Wt. %) was examined using the modified Crussard-Jaoul analysis. It was shown that these dual-phase steels
deform in two stages over a uniform strain range. Each stage exhibited a different strain hardening exponent varying
with silicon content. At the first stage, work hardening exponent remind significantly constant, while during the second
stage, it decreased with increasing silicon content from 0.34% to 1.51% and then increased for the higher silicon
contents (1.51% to 2.26%). It was found that the strain hardening behavior of these steels was predominantly affected
by the volume fraction of martensite at low silicon contet and the ferrite strengthening induced by silicon at the higher
silicon content. The effect of silicon content on the volume fraction of martensite and tensile properties were also
considered.
Sahar Ziraki, Amir Moghaddam Kia, Ramin Ebrahimi,
Volume 21, Issue 0 (3-2024)
Abstract
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.
