Effect of scratch rate on FeO/Fe fracture of single crystal studied based on MD
The fracture behavior and mechanical properties of oxide are the key factors affecting the parameters set-ting of acid-free descaling process.Molecular dynamics software Lammps was used to simulate the effect of scratch rate on the fracture behavior of oxide scale.The effects of different scratch rates on the separation of FeO/Fe inter-face were analyzed from the perspectives of load-displacement relationship,CSP,atomic accumulation,dislocation,temperature,atomic displacement vector and radial distribution function,and verified by scratch test on the oxide scale of 430 stainless steel surface.The simulation results show that as the scratch rate increases from 100 m/s to 200 m/s,the normal and tangential peak load gradually increases,the disorder degree at the FeO/Fe interface in-creases,and the temperature increases when the scratch reaches the same distance,which makes the FeO layer grad-ually soften,and the length and number of dislocation and atomic bonding strength gradually decrease,promoting the separation of the FeO/Fe interface.Test results show that with the increase of scratch rate from 0.5 mm/min to 2.0 mm/min,the breaking point of 430 stainless steel oxide is advanced from 1.26 mm to 1.05 mm from the start-ing point,the critical load and bonding strength are gradually reduced,and the critical load is reduced from 0.439 N to 0.362 N.The binding strength decreases from 15.2 MPa to 14.1 MPa,which corresponds to the trend of simula-tion results.This study provides theoretical support for understanding the fracture mechanism of the oxide scale,and provides important guidance for improving the accuracy of parameter setting for acid-free descaling.
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