Effect Of Heat And Shear Stress On Shear Band Formation During Machining Of Amorphous Alloy

Vit1 metal glass is a kind of amorphous alloy which is obtained by rapid solidification technology to rapidly cooling high temperature alloy melts to avoid the appearance of crystallization inside the melt.Metallic glass has amorphous structure and no microstructural defects of crystalline metal materials.Therefore,metallic glass has good physical,mechanical and chemical properties,and has been widely applied in military,aerospace,power and sports equipment.In the process of deformation,amorphous alloy is prone to produce localized shear bands and is accompanied by temperature and stress changes.Understanding the "thermal-force" in the process of shear band formation is the premise to clarify the deformation mechanism of metal glasses and understand the formation mechanism of shear bands.We focus on the changes of temperature and stress in the produce of shear band.From the perspective of the constitutive model of metal glass,we establish a two-dimensional orthogonal cutting simulation model of Vit1 metallic glass by AdvantEdge finite element software to research the change of "thermal-force" in cutting process.Firstly,because of the current problems of material model of finite element simulation software is not suitable to describe the deformation process of amorphous alloy,we consider of the character that amorphous alloy is sensitive to temperature and stress,using the constitutive relations of Drucker-Prager as the constitutive model for Vit1 and establish the geometric model of cutting simulation.We compared the maximum temperature of Vit1 3D turning simulation with the maximum cutting temperature reported in the literature.The maximum deviation of the two dates is 12.5%,which confirms the correctness of the cutting simulation constitutive model,and we lay a good foundation for the later "thermal-force" analysis.Secondly,based on the two-dimensional orthogonal cutting simulation model,we research the influence of different cutting parameters and different geometrical parameters on the temperature and thermal softening of the amorphous alloy cutting process.After that,we analysis the reason which changes the thermal softening time in the cutting process of Vit1.Finally,aiming at the origin of the shear band of amorphous alloy,we analysis the influence of cutting parameters and different tool geometry parameter on the max shear stress and shear stress softening in shear deformation zone.At the same time,we compared the thermal softening time and shear stress softening time,and it is found that the time of shear stress softening at the same cutting condition is much smaller than that of thermal softening time.