Influence of temperature on stress distribution in bainitic steels -Application to 16MND5-A508 pressure vessel steel

In this study, the internal stress evolution of the ferrite phase of 16MND5-A508 has beendetermined using X-Ray Diffraction (XRD). The results of in situ tests combined with XRD analyses and performed at different temperatures (-150°C and 22°C) exhibit a difference of about 200MPa between the macroscopic stress and the ferrite one. The stress state in the cementite is determined by a mixture law; it reaches very high values up to 9000MPa. These results highlight the need to analyze the stress directly in the cementite phase by using appropriate tools, since its volume fraction does not allow it using XRD.