Process And Structure Property Of Electromagnet Treated By Nitriding/Quenching

Electromagnet has high permeability and low coercivity,and is used in the weaving machine as core electromagnetic element.Because of electromagnet needs frequent absorption and separation,the electromagnet is required to have a certain hardness and impact resistance.The domestic electromagnet sells for a low price,but the life of the electromagnet is only one year,while the life of the foreign electromagnet is five times that of the domestic electromagnet,but it is expensive.Therefore,it is great significance to study the domestic electromagnet and the surface strengthening process of electromagnet.Firstly,the microstructure and composition of foreign electromagnet was tested and analyzed by metallograph,EPMA,the phase analysis was performed by X-ray diffraction,and the impact resistance was measured in self-made,impact tester.The results showed,that the domestic electromagnet had three layer,the surface layer was a 10μm thick compound layer,the hardness was 402HV/0.05,the subsurface layer was 50μm thick,and the hardness was 341.4HV/0.05.The diffusion layer was a phase+γ’ phase and the hardness was 112HV/0.05.Thus,the nitriding and quenching treatment process was developed for the electromagnet.In this paper,the electromagnet was treated by gas nitriding,the effect of differert parameters on the microstructure and the properties of electromagnet was studied,and the impact resistance test was performed.The results showed that with the increas of nitriding temperature and the nitriding time,the nitriding layer wa more deeper and denser,after the impact test,the surface wear of electromagnet is serious,resulting in the 0.7mm deep impact crater and produced a 0.3mm deep impact crater on the friction pair and did not meet the electromagnet process.In this paper,the electromagnet was treated by salt bath nitriding,the effect of differert parameters on the microstructure and the properties of electromagnet was studied,and the electromagnet of suitable process was selected.On this basis,the nitrided electromagnet was martensitically quenched and isothermally quenched,respectively,and the effects of the different tempering temperature,different austenitizing temperature and different isothermal temperature on microstructure and.properties of electromagnet were investigated,and it is concluded that the best heat treatment process of electromagnet,and the impact tests of treated electromagnet and foreign electromagnet were compared and analyzed.Through the system test and analysis,the conclusions are as follows:(1)When the electromagnet was treated at 560 ℃ for 0.5h,the surface hardness is 351HV/0.05,the nitriding deeps is 0.25mm,and the electromagnet grain is refined.(2)Nitriding electromagnet was obtain a layer of 30μm nitric martensite after the oil quenching treatment.With the tempering treatment,the nitric martensite transforms into tempered martensite and bainite.When tempered at 300 C,the hardness of the surface layer is 530.3HV/0.05.After impact test,the electromagnet surface was slightly worm,and a 0.5mm deep wearing surface appeared.However the friction pair was severely detached,resulting in a wearing surface of 1.3mm deep,which does not meet the technical requirements.(3)Nitriding electromagnet was obtain a layer of 40μm nitric bainite after the isothermal quenching treatment.The hardness of the austenitizing temperature at 750 C is 355.3HV/0.05,the nitriding deeps is 0.5mm.The bainite microstructure obtained by isothermal quenching at 300 ℃ is dense and the surface hardness is 353 HV/0.05,which is in accordance with the requirements of the electromagnet.Therefore,the induction of the electromagnet heat treatment process is salt bath,nitriding at 560 ℃ for 0.5h,then austenitizing temperature at 750 C and isothermal quenching at 300 C for 1h.(4)After impact test,the domestic electromagnet was severely dropped off,and the depth of the wearing surface was 0.6mm,the isothermal quenching electromagnet was lightly worn and the deep wear was 0.5mm.Foreign magnetic friction pair produce a large number of cracks on the surface,the isothermal quenched magnetic wears on the surface is relatively light,and the depth of wearing surface is 0.5mm.Therefore,the impact resistance of isothermal quenching electromagnet is better than that of foreign electromagnet.