| Cracks,holes,inclusions and other defects are the most common form of defects in components.If some important core components are cracked,they will only be scrapped,and cause huge economic losses.Electromagnetic heat hardening is a non-equilibrium technology developed in recent years,which not only can repair internal defects of components,but also improve the mechanical properties of components.The study of repairing the internal defects of reinforced upsetting components by electromagnetic thermal technology has not been involved.In this paper,the combination of theoretical analysis,experimental research and finite element analysis were used to study the crack arrest of the upsetting component of 20 CrMnTi steel with electromagnetic heating technology.The main contents of the study are as follows:The upsetting cylinder theory of the flat plate was introduced.Based on the Cauchy integral basic mathematical knowledge,analysis model was established with intermediate crack two-dimensional infinite thin plate theory by using the complex variable function method,analysis of the temperature field in the crack tip region of the discharge,and the temperature field at the tip of the crack tip,the stress field and the stress intensity factor was analyzed.The temperature field at the tip of the crack tip of the upsetting specimen with crack 20 CrMnTi steel were analyzed by an example.The upsetting specimen of 20 CrMnTi steel with crack was prepared by upsetting,and the optimum discharge voltage was determined.The ZL-2 super pulse discharge device were used to discharge specimens,and specimens before and after the discharge were tested by metallographic test,point component analysis,XRD analysis,microhardness test,XRD stress test,SEM tensile fracture scanning test.From the micro angle,the effect of electromagnetic heat strengthening on the crack arrest of the upsetting specimen with crack 20 CrMnTi steel was compared and analyzed.The tensile and section shrinkage test of the specimens before and after the discharge are tested,and the effect of electromagnetic heat strengthening on its mechanical properties is compared and analyzed from the macroscopic aspect.The finite element analysis model of upsetting and discharging of 20 CrMnTi steel was established by using ansys software,and the strengthening process of the upsetting of the crack with the pulse current was simulated and analyzed,and the stress distribution inside the upsetting process and the temperature field,stress field and the distribution of the current density in the front of the crack under the best pulse discharge voltage were given.In this paper,the feasibility of electromagnetic crack arresting technology for cracking strengthening of upsetting components containing 20 CrMnTi steel was verified from theoretical analysis,experimental research and finite element analysis,and the application of electromagnetic thermal technology in the repair of internal defects in upsetting parts was sufficient technical support. |
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