Fatigue Life of Stabilizer Bars and Specimens for Two Microstructural Conditions: Pearlitic and Martensitic

The current study proposes to approach the fatigue behavior of stabilizer bars and specimens manufactured in quenched / tempered and as-received SAE5160 steels with and without a surface micro-notch. Some S-N specimens and stabilizer bars were shot-peened to improve the fatigue strength due to creation of compressive surface residue stresses and by surface plastic strain and others samples received a surface micro-notch of 0.3 mm depth introduced by EDM process. The crack growth evaluation at micro-notch was made comparatively with da/dN-ΔK curves in CT specimens.

The proposed experimental study consists of comparative analysis of da/dN-ΔK and S-N curves, fractographic and, metallographic analysis, stabilizer bar bench tests, and after that, it is intended to show the relevant aspects of two microstructural classes currently specified for stabilizer bars, the beneficial effects obtained by shot peening and the bad influences of surface micro-notches. The main objectives of this study are to show the differences in behavior between both microstructures, the fatigue life reduction when a micro-notch is present on surface and, as a result of that approach, what is more important for a stabilizer bar: to withstand the fatigue crack nucleation or fatigue crack growth?