In this study, we will be interested in characterizing for two grades of metallic materials, the base metal on the one hand and the material of the welded joint, which is a priori, the critical part of the part that may present a risk of premature failure by compared to the base metal. Consequently, the emphasis is placed in this document on the study of the monotonic and cyclic behavior of austenitic molybdenum stainless steel AISI 316L and their joints welded by the MIG process after a finishing treatment (brushing and heat treatment). The cyclic behavior is characterized mainly by cyclic hardening, low cycle fatigue and cracking tests. The study of the damage mechanisms of each metal as well as the origin of the rupture is a complement to the understanding of the studied behaviors.