Résumé:
The aim of this study is to analyse the mechanical properties of low alloy steel
42CrMo4, used for the manufacture of bolts and threaded roads by Oil Company. We
consider an experimental approach based on tensile, impact fracture toughness and
hardness tests. The mechanical properties investigated concern the tensile strength, the
elongation and the ultimate tensile strength as well as the rupture energy obtained through
resilience measurements. Tempering treatments are varied from 200 to 600°C in order to
investigate the influence of microstructure. We show the variation of the relevant
parameters as a function of the tempering treatment. These treatments reveal the influence
of tempering.
The determination of rupture energy through resilience tests helps develop an
experimental data bank libely to implement models capable of studying this energy as a
function of various parameters such as stress triaxiality, microstructure of a low alloy steel
42 CD 4 and stress rate. Significant dispersions in the resilience determination were
observed. They stem from the chemical or microstructural heterogeneities of the steel under
investigation, thermal treatment conditions, stress rate, the presence of crachs which may
favour stress triaxiality and from setup and environmental conditions of the tests. The
experimental design allows the determination and the understanding of relation ships
expressing rupture energy as a function of the various parameters investigated.
