Fatigue of steels used in the manufacture of components for heavy load vehicles

Abstract

The demand for the reduction of pollution emissions and of fuel consumption has promoted the reduction in weight of passenger and heavy load vehicles. In particular in these last ones, it is not only desired to reduce the weight, but also to increase their load capacity, which may put in risk critical components, with special attention to their resistance to fatigue, to assure the reduction in cross-sections without impairing their mechanical behavior. The procedure followed to study the resistance to fatigue in steels hardened by different means is presented. The steels were obtained in their warm formed condition, which is the conventional one, or in their heat treated condition, to enhance their mechanical properties. The fatigue tests were conducted in cylindrical samples machined to hour glass geometry and tested in bending conditions. The fatigue limit was obtained by following staircase methods. The fracture surface of the samples was analyzed by scanning electron microscope to deduce their tenacity. The results obtained will allow for modification of the manufacturing procedure of components to enhance their performance.