Characterization of a Mild Steel by Its Mutual Tensile Mechanical and Micromagnetic Emission Response After Corrosion in NaCl – Water Solution: a Combind Semiquantitive Approach

Abstract

In this work, the influence of corrosion – induced hydrogen accumulation on a stressed low- carbon steel after exposure to NaCl - water solution was investigated by means of its combined tensile mechanical and Micromagnetic emission (ME) - response. The investigation was conducted by employing certain relevant parameters and processes of mechanical and magnetic microstructural changes. The mechanical and Micromagnetic response data were reduced to the ultimate tensile strength as well as to maximum (ME) - response respectively where certain critical- characteristic microstructural- transitional changes take place. Under these conditions and by an appropriate procedure of “consecutive - selective discrimination steps” of the related affecting factors their differential influence on the mechanical and ME – response was better revealed, compared and analyzed. In this manner it was demonstrated that the detrimental influence of cumulative hydrogen arises in from of mechanical embrittlement which can be related to a parallel magnetic hardening trend of the material. The explanations are given on the basis of highly localized and competitive or opposing processes of void initiation- growth and stress relive, resulting by a common lattice diffusion, as well as moving dislocation- aided transport of hydrogen to the affected sites. Within the frame of the above findings it was shown that the ME-response presents, compared with mechanical response, an increased sensitivity making the first a superior technique in early detecting hydrogen- assisted microstructural damage in loaded steel components