Effects of Shot Peening on Surface Layer States and Fatigue Behavior in Experimental Casts of Enhanced Leaf Spring Steels

Shot peening under pre-stress (“stress peening”) is widely used for the mechanical surface treatment of steel leaf springs in heavy truck applications. In this paper, we present the effects of stress peening, applied to experimental batches of four new leaf spring steels. After an examination by means of chemical analyses, microscopy and dilatometry, quenched and tempered specimens of the experimental steel grades were subjected to single and double shot peening under pre-stress at ambient and elevated temperature. Surface layer states were characterized by means of X-ray analyses of residual stresses and full width at half maximum (FWHM) as well as roughness measurements. The fatigue behavior was evaluated using laboratory scale (small) specimens in alternating bending. The shot peening variants gave rise to comparable results, whereas the most pronounced effect could be attributed to the selected steel grades and their respective heat treatment.