Effect Of Deformation On Corrosion Performance Of High Manganese Steel

The pre-hardening and deformation during service will cause the high-manganese steel structure properties to change,and the corresponding corrosion to change.This article aims to study the influence of deformation on the corrosion performance of high-manganese steel,which can provide a reference for its corrosion evaluation and protection in service environment.According to the changes in the microstructure and properties of high manganese steel,four representative deformation amounts of 0%,20%,40%,and 60%were selected for research.High-manganese steels with deformations of 0%,20%,40%and 60%deformations are studied.In order to investigate the effect of deformation on Corrosion behavior of the test steel,including electrochemical tests,slow strain rate tensile tests,and salt spray corrosion were employed.Characterization methods such as Optical microcope and X-ray diffraction,EBSD and TEM have been applied to analyse the effect of cold deformation on the microstructure.Moreover weight-gain method and electrochemical methods such as polarization curves,and electrochemical impedance spectra?EIS?measurements were carried out to study the high-manganese steels with different deformations under different conditions.In combination with comparing the surface corrosion morphology via SEM and analyzing the rust layer composition to explore the corrosion mechanism.The results show that the high-manganese steel grains are stretched along the rolling direction,and with increasing rolling deformation,the dislocation density and the number of deformation twins gradually increases.The dislocation motion was blocked by the formation of twin boundaries.As a result,the hardness of the test steel increases;Along with the amount of rolling deformation,the density of dislocations increases obviously.It makes the sample surface in a highly disordered state and increases the electronic activity of the surface.The improvement not only provides more channels for the rapid transmission of anions and cations,but also promoting the formation and development of slip steps.therefore numerous dislocations promote the progress of chemical reactions.A combination of stress and corrosive media have effect on he high-manganese steel ventually resulted into the increase of tensile strength,the decrease of elongation and the fracture mode shows brittle fractures.Thence,it has bad influence on plastic toughness.Wha's more,the austenitic high-manganese steel with large deformation is more sensitive to stress corrosion cracking.Steel matrix activity and the rust layer are two main factors,which affect the corrosion resistance of austenitic high-manganese steel in salt spray test.The rust layer is mainly consisted of?-FeOOH,?-FeOOH,?-FeOOH,Fe₃O₄ and so on.High-manganese steel with large deformation has poor corrosion resistance due to the greater activity of the steel matrix and plenty of more reactive?-FeOOH and Fe₃O₄ accumulated in the rust layer.