STATISTICAL STUDY OF THE DEPENDENCE BETWEEN CONCENTRATION OF METALLIC ELEMENTS MIGRATED FROM STAINLESS STEEL GRADE AISI321 AND WORKING PARAMETERS

Abstract

One  of  the  main  problems  concerning  food  safety  is  the  possible  migration  of  ions  in metallic materials intended to come into contact with food. The aim of  this  paper is  to find  and apply the  mathematical  modeling of experimental  data  which should  describe  as  accurately  as  possible the dependence between  the  variables  used  in  the experimental plan. The research made and presented in this study also aims to create a real possibility for rapid intervention in the process control when one of the parameters cannot be maintained at a predetermined value. In this paper we used some experimental data obtained by testing the migration of metal ions from austenitic stainless steel grade AISI 321 samples in solutions with concentrations of 3%, 6% and 9% acetic acid. To find an accurate mathematical model describing the phenomena of diffusion, ANOVA method, known as the variance analysis, was used. In order to obtain the mathematical model we used a polynomial model with independent variables: corrosive environment temperature  (X₁),  exposure  time  (X₂),  stirring  environment (X₃) and the dependent variables Y - concentrations of elements Ti, Cr, Mn, ⁵⁶Fe and Ni found  in solutions. Values of the regression coefficients very close to the value 1 (the dependent variables coefficients are valid) were obtained, which demonstrates the validity of the applied method.