Fatigue Damage Analysis And Modeling Of Cemented Carbide Tools Rake Face

The barrel material 2.25Cr-1Mo-0.25 V is the first choice material for manufacturing large reaction vessels such as hydrogenation reactors and nuclear reactors which is widely used in coal,petrochemical and other industries.The carbide cutting tools with the advantages of high strength,high hardness,high wear resistance and high toughness are usually used in the cutting process of barrel materials.During the cutting process,the cemented carbide tools endure the combined action of cyclic mechanical load and thermal load which are lower than its static strength limit,and causes many kinds of micro defects to sprout inside or on the surface of the tools(Slip,dislocation,stress induced phase transformation,etc).Meanwhile,with the micro defects(micro holes,micro cracks,etc.)of the tools themself expand and enlarge together,which makes the tools appear fatigue phenomenon.When this kind of defect evolves to a certain size,it will reduces the strength of the tools themself(the ability to resist damage),and the tools will cause fatigue damage,which will lead to the matrix material being taken away by chips or materials,making the tools invalid.The fatigue damage evolution process of cemented carbide tools is closely related to its own fatigue characteristics,therefore,it is very important to find out the fatigue characteristics of cemented carbide tools.And for the fatigue failure phenomenon of carbide tools turning barrel material in-depth research.Firstly,the experiment platform of intermittent turning of cemented carbide tools was built.The cemented carbide YT15 tools with different cutting parameters were obtained,the front face fracture of the failed tools was observed by SEM,and the micro morphology of the failure was analyzed from the fracture mechanism.The application of damage mechanics in tools failure is analyzed.Based on the theory of damage mechanics,combined with the actual working condition and physical properties of cemented carbide tools,the damage form of cemented carbide tools is determined as fatigue damage,which provides a theoretical basis for the subsequent establishment of fatigue damage model.Secondly,the tensile and compressive fatigue test of YT15 cemented carbide tools material was carried out.According to the national standard design and manufacture standard tensile test pieces,develop experiment plan,and analyze the experimental results,finally get the function relationship between its life and loading stress,get the fatigue characteristics of cemented carbide material YT15,and determine the fatigue limit of cemented carbide tools material YT15,provide data for parameter fitting in fatigue model.Thirdly,the fatigue simulation of cemented carbide is carried out.Using ANSYS according to the physical properties,the material simulation parameters are established.Getting the change rules of stress,strain,damage of the specimen and stress life data.Drawing the S-N curve.The fatigue test is verified and the basis for calculating the damage evolution equation of cemented carbide tools is provided.Finally,the fatigue damage model of YT15 is established.Firstly,the damage variable is selected according to the damage form and the actual working condition,and the damage variable is represented in the form of function.Secondly,based on the theory of strength degradation,the fatigue damage model of cemented carbide tools is established.Finally,according to the data of experiment and simulation,the strength degradation parameters in the model are fitted by Python software,and the fatigue damage evolution equation of cemented carbide tools is obtained.