Influence of Crystall Structure on Corrosion Resistance of 316 Stainless Steel by First-Principles Calculation
The problem of corrosion resistance of 316 stainless steel has always been a hot topic for researchers.The crystal total energy and electronic structure of austenite,ferrite,Fe alloy and cementite in the 316 stainless steel were simulated and computed by the CASTEP module of the Materials Studio software.The influence of crystal total energy,band structure,electronic density of states of crystal phase in the 316 stainless steel on the corrosion resistance has been investigated by the first principles method based on the density functional theory(DFT).The total energy results showed that the most stability of crystal phase in the 316 stainless steel were Fe alloy and cementite,next was austenite,and finally was ferrite.It suggests that the corrosion resistance of Fe alloy and cementite has higher than austenite and ferrite.Additionally,the crystal total energy of Fe-Cr alloy decreased with increasing Cr content.It is implied that adding Cr content can improve the stability and corrosion resistance of stainless steel as 316 stainless steel is being corroded.Besides,the results of band structure and electronic density of states display that the band width of cementite and Fe alloy decreases,and their locality increases.But the band width of ferrite becomes large and its non-locality increases.It indicates that the stability and corrosion resistance of cementite and Fe alloy are higher.With the increase of Cr content,the energy corresponding to the maximum peak of Cr-containing austenite is lower,the number of extranuclear electrons distributed in the region is less,the distribution of extranuclear electrons is less,the electrons are not easy to lose,and the redox reaction is not easy to occur,and the structure is more stable.During the corrosion process,the austenite structure with high Cr content is more stable and the corrosion resistance is better.This conclusion is consistent with poor chromium theory or intercrystallite impurity segregation theory.
316 stainless steelcrystal structurefirst-principle theorymetallurgical structurecorrosion resistancecrystal total energyband structureelectronic density of states
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