Electromagnetic Thermal Crack Arrest And Strengthen On Metal Component With Spacial Circal Embedding Crack

It is a novel and effective method for stopping internal and surface crack propagationin metal components by electromagnetic heating effect. There is a lack of systematictheoretical and experimental research on embedding crack arresting at home and abroad.The work is based on the thoughts, and the electromagnetic heat is applied to embeddingcrack in theoretical analysis, numerical simulation and experimental surveys.Theoretical analysis is made on the strain energy density at the time of pulse currentdischarge in a metal structure with a circular embedding crack. he strain energy densityformula are obtained at time of pulse current discharge，And taking an example ofCr12MoV die steel with a circular embedding crack, changes of strain energy before andafter pulse discharge is calculated under different tensile stress.The current density is deduced by fluid mechanics in metal with embedding inclinedcrack and is translated into metal with embedding circular crack. Stress intensity factorexpression is also obtained after discharge. An example gives current density and thestress intensity factor relation curves.Using the ANSYS to simulate stress intensity factor the before and after discharge.Simulate 45 steel temperature field and thermal stress field at the moment of pulsedischarge. The electromagnetic strengthening technology is applied to castings with holesdefect, and temperature filed in theory is deduced. Temperature field and thermal stressfield are simulated by ANSYS.Manufacture embedding crack in 45 steel through the hot pressing and interference fit.Use TZ-2H ultrasonic nondestructive testing detector to detect the location of the crack incomponent. The change of residual stress around the embedding crack tip before and afterpulse discharge is checked using the ultrasound contrast method. The experiment ofelectromagnetic heat crack arrest is conducted on ZL-2 pulse current generator. Macromorphology near crack tip is observed before and after pulse discharge by the microscope.The stretch and torsion property tests are carried out. And the mechanical performanceanalysis is studied before and after pulse discharge. The paper provides the reference for further study of embedding crack arrest.Numerical simulation results, the theoretical analysis and experimental phenomena cantest that the technology of electromagnetic heat crack arrest is applied to the welding field.