Research On The Influence Of Si And Mn Elements And Processing Technology On The Performance Of Iron-based Electromagnetic Materials For Shielding

In recent years,steel materials have gradually evolved into high-quality,low-cost,structural and functional integration.Due to the poor mechanical properties of traditional metal ferromagnetic shielding materials,it has brought a lot of inconvenience to production and processing,which limits its application range,which puts forward higher requirements for its magnetic properties and mechanical properties.Therefore,in this paper,iron-based electromagnetic materials as the research object,by adding solid solution strengthening elements Si and Mn,hot rolling process and annealing process to improve magnetic properties and mechanical properties.In this thesis,the Thermol-calc is used to calculate the phase transition temperature,different finish rolling temperature hot rolling,series temperature annealing,metallographic observation and analysis,EBSD grain orientation analysis,DC magnetic performance testing,shielding effectiveness testing,room temperature tensile test and other means A study was conducted and the following conclusions were obtained:(1)Si alloys do not undergo phase transformation during high-temperature annealing.Grain size and homogeneity increase with increasing annealing temperature.Si alloys have coarser and more uniform grain sizes when annealed at high temperatures,and Mn does not undergo ???.A relatively coarse and uniform structure can be obtained when the maximum temperature of the phase transition is 880°C.(2)Mechanical properties,the best alloy composition and process are experimental materials containing 1.4% Si,840 °C finish rolling,1100 °C annealing.The best mechanical properties at this time were: tensile strength of 359.0 MPa,yield strength of 218.5 MPa,and elongation after breaking of 33.0%.(3)Magnetic properties,the best alloy composition: Si system is 1.4% Si,Mn system is 1.0% Mn plus 0.1% P;optimal annealing temperature: Si system is 1100°C,Mn system is 880°C;0.1% is added P is unfavorable to magnetic properties of Si-based iron-based electromagnetic materials and is advantageous to Mn systems.The shielding effect of the Si system is better than that of the Mn system.(4)As the finish rolling temperature gradually increases from 770°C to 920°C,the [111] component in the magnetically unfavorably hardened direction first decreases sharply and then increases slowly,favoring the(110)[001] component gradually.With the increase,the deviation degree increases first and then increases.The final rolling at 840°C is most favorable for the magnetic properties.(5)In the experimental materials,the best alloy composition and process from the viewpoint of comprehensive magnetic properties and mechanical properties is that the final rolling temperature is 840°C when hot-rolled with 1.4% Si experimental material,and after annealing at 1100°C,it is weak at DC and low frequency.The measured shielding effectiveness in the magnetic field environment is 13.92 dB comparable to that of Permalloy.In summary,the Si element increases the phase transition temperature,so that no phase transformation occurs during annealing at high temperature,and it is easier to obtain a coarse and uniform equiaxed ferrite grain structure,which plays a significant role in optimizing the magnetic properties of the experimental materials.At the same time,the increase of grain size will cause some damage to the mechanical properties.The strengthening effect of the solid solution strengthening element Si can remedy or even exceed the strength loss due to the organizational factors to some extent.