MECHANICAL AND MICROSTRUCTURAL STUDY OF RESIDUAL STRESSES INDUCED BY SHOT PEENING ON THE FATIGUE STRENGTH OF AISI 4340 STEEL

摘要

Many factors controlling the fatigue resistance of a metal have been studied, considering the great number of mechanical components subjected to variable amplitude loading in high responsible applications, for example, landing gear. On the present research the fatigue strength of 4340 steel is evaluated as a function of shot peening conditions. For this , bending fatigue tests were carried out to clarify the strengthening effect of peening and to obtain the fatigue strength of peened specimens and base material. To analyze the fatigue experimental data, the compressive residual stress field was measured in an x-ray tensometry apparatus and the fracture of the fatigue specimens were investigated using a scanning electron microscope. Some correlation between them are discussed.