Characterization of chemical heterogeneity of the welded joint of two steels by modelling of diffusion processes

Abstract

The paper deals with original methodology for characterization of chemical heterogeneity of welded joint by measurement of concentration profi les of substitution elements in three straight lines in a plane perpendicular to the weld interface. Three concentration profi les were evaluated by modelling of diff usion based on solution of the 2nd Fick’s law. Primary goal of evaluation consists in characterization of chemical heterogeneity in the narrow area on both sides of the welded joint on the basis of their mutual position. Experimental data are optimised by original adaptation of the Levenberg-Marquardt’s algorithm of non-linear regression. The paper deals with diff usion of nickel in the welded joint of two diff erent steels as an example of investigated elements.