Molecular Dynamics Study on Adding Tungsten‐Carbide Grains to 304 Stainless Steel Polycrystals

Abstract

The molecular dynamics method is conducted to study the mechanical properties and plastic deformation mechanism of composite materials ASSN‐WC with tungsten carbide (WC) grains added to 304 austenitic stainless steel nanopolycrystals (ASSN) during uniaxial tensile process. The results indicate that the overall strength of ASSN with void defect is decreased, and because of the larger shear model of WC crystal, the overall strength of ASSN‐WC material is improved, and its toughness is not significantly reduced. In the plastic deformation process, under low strain conditions, the main deformation mechanism inside polycrystals is dislocation slip. The slip of dislocations forms extended dislocations and stacking faults, which makes the grains deform. As the strain increases, the dislocation slip inside the grains becomes more intense, and deformation twins appear. The interaction between slip dislocations and grain boundaries makes the grain boundaries hinder the further deformation of the grains, and the strengthening effect on the local area of the material becomes more obvious. Meanwhile, in the process of strain increase, the WC grains do not rotate and deform. This can also effectively hinder the deformation of other grains on the adjacent edges and improve the stiffness of the composite material.