The effect of martensite content on the fatigue of a dual-phase steel

Cyclic Deformation of Advanced High-Strength Steels: Mechanical Behavior and Microstructural Analysis

“…This softening generated cyclic stress levels well below that of the as-received yield stress. Previous studies on dual-phase steels [12,13] have predominantly shown cyclic hardening behavior over similar ranges of strain amplitudes to that used in this current study. Typical dual-phase steels, however, have a lower yield point to tensile strength ratio than the steel used in the currently study, resulting in significantly higher initial work-hardening rates.…”

“…Sherman and Davies examined dual-phase steels with differing martensite contents, and hence yield strengths under fully reversed cyclic straining. [12] In that study, the fatigue life increased with increasing martensite content, hence strength, until approximately 30 pct martensite before decreasing with further martensite increase. This highlights the importance of ductility in fatigue life, as at the higher martensite volume fraction the strain life decreased with increasing yield strength due to a decrease in material ductility.…”

“…Research using strain-controlled fatigue has also shown the importance of the microstructure in different steels on the cyclic stress response, specifically, whether the material will soften or harden with repeated cyclic plastic. [12][13][14][15][16] Previous studies have shown both cyclic softening and hardening for ferrite-based steels (depending on strain amplitude), [14] cyclic hardening for ferrite-martensite based steels, [12,13] and cyclic softening for austenite-based stainless steels. [16] These differences suggest that for more complex microstructures containing multiple phases, such as TRIP steels, the cyclic stress response will depend on which phases are accommodating the strain.…”

Effect of welding heat input on fatigue life of quenched boron steel and FB steel lap joint

“…In addition, since the plastic strain decreases when increasing the yield strength at a given total strain amplitude in a low cycle fatigue test, the fatigue life increases when the plastic strain energy per cycle is decreased [3,4]. However, chassis parts are manufactured with ultra high strength steel, like quenched boron steel, and high strength steel, like ferrite-bainite (FB) steel, and assembled using gas metal arc welding (GMAW).…”

The effect of low cycle fatigue, ratcheting and mean stress relaxation on stress–strain response and microstructural development in a dual phase steel

“…LCF performances of DP steels are characterized by a number of research groups [7][8][9][10][11], where typical behavior shows strain partitioning between the phases, the development of substructure in the ferrite, and initial cyclic hardening followed by subsequent softening. However, the authors have not found extensive experimental literature on MSR and ratcheting response for DP steel.…”