Experimental Study And Simulation Analysis Of Fatigue Failure Of Milling High Strength Steel With Carbide Tools

The head of the water chamber is an important part of the steam generator of the nuclear island nuclear power plant.Its main processing method is heavy milling.The material is high-strength 508 III steel,which has the characteristics of plasticity,hardness,and high strength.Carbide cutting tool materials are brittle materials.The initial damage and cutting defects in the cutting process during the preparation of the cutting tool,under the action of high temperature,high pressure and cyclic load,the internal micro-defects continue to accumulate and initiate and cause macro cracks,Leading to severe tool fatigue failure,reducing tool life and machining efficiency.In view of the above problems,the fatigue failure experimental research and simulation analysis of milling high-strength steel carbide tools are carried out.Firstly,milling high-strength steel machining experiments are performed to analyze the fatigue damage morphology of the tool and determine the main failure modes of the tool.The microstructure of the carbide tool material is analyzed to obtain two crack nucleation modes at the heterogeneous interface and the initial crack.Analysis of tool material crack growth in terms of load and temperature provides theoretical basis for fatigue failure research of cemented carbide tools.Secondly,study the damage parameters of cemented carbide tool materials,and establish a fatigue damage model of cemented carbide tool materials;perform high temperature mechanical performance tests and simulation analysis on cemented carbide tool materials,and compare and analyze them.The change trend and the detection of fracture cracks of the test piece based on Open CV provide a theoretical reference for the study of fatigue damage evolution of cemented carbide tool materials.Further,the micro-mechanical damage of the tool material was investigated to determine the process of the damage evolution and formation of the tool material.The three-point bending crack growth test and simulation analysis were performed on the carbide tool material to obtain the change trend of the crack growth rate and stress intensity factor amplitude.And the relationship between the crack length and the number of cycles,the change curve of the crack tip energy with time and the fatigue damage evolution curve are established to provide technical support for the study of the fatigue life of the carbide tool materials.Finally,the displacement field and stress field of the three types of crack tips are analyzed,and the fracture criterion of the carbide tool material is established in combination with the stress intensity factor;the crack is explored from the width of the carbide tool material model,the pre-formed crack length,and the applied load.The change law of the stress intensity factor of the tool material during the expansion;The dynamic expansion simulation analysis of single and multiple cracks of the carbide tool material is provided to provide a technical reference for the study of fatigue cracks of the carbide tool material.