Redistribution of hydrogen in steel weldments - Part I. Fe-H-C-i austeniteaustenite type weldments

A new analytical quasistationary diffusion model of hydrogen and carbon dif fusion in Fe-H-C-i austenite/austenite type weldments is presented. The new model extends the experimentally verified and published quasistationary Fe -C-i model of hydrogen. The diffusion rate of hydrogen is of many orders hi gher than the substitutional elements diffusion rate and of also several or der higher than carbon diffusion rate. Thus, the redistribution of hydrogen imitates the redistribution of carbon and distribution of substitution ele ments, while the redistribution of carbon imitates only the distribution of substitution elements. The new model is presented in the form of a system of the analytical relati ons. Using the thermodynamic, diffusion, and phases data, it is possible, b y means of this relations, to calculate the i-elements, carbon and hydrogen concentration curves in the austenite/austenite steel structure weldments at different temperature and time of annealing. The limiting conditions of the presented quasistationary model in the above -mentioned welding joints are discussed.