Effet de l’hydrogène sur le comportement mécanique des aciers à moyenne et haute résistance utilisé dans le transport et le stockage de l’hydrogène sous pression : Prise en compte de la variabilité spatiale de la diffusion de l’hydrogène dans la fragilisation de ces aciers

Abstract

Steelmakers have always faced the problem of embrittlement of steels by hydrogen for this, several methods based on complex mathematical models could not lift the veil on the complexity of the phenomenon for that the objective of this work aims to use simple effective and rigorous methods. This thesis is augmented by two main parts, the first covets a probabilistic approach applied to a high-strength steel C-Mn it is steel used in the field of civil engineering which displayed a certain vulnerability to hydrogen during the development of the latter in the drawing operation stage. The Monte Carlo simulation method is based on the second diffusion law and introduces the random nature of the parameters which govern the hydrogen desorption by modeling them in random fields in order to determine an optimum duration for its escape. in order to reduce the harmful effect of hydrogen on the use of this material. The second part uses analysis by artificial neural networks (ARN) mimicking the functioning of the human brain. This method is experiencing a strong revival of interest giving satisfactory results thanks to the power of the mass of data (big data). Based on experimental results which relate to the study of the susceptibility of 42CrMo4 (AISI4140) steel to hydrogen, this steel has been deceived and returned to different temperatures the application of artificial neural networks is proposed to predict the optimal tempering temperature in order to contain a minimum quantity of hydrogen in a metal by analyzing the parameter of hydrogen concentration which escapes by desorption over time at room temperature