Study On The Optimized Process And Mechanism Of1J50Alloy Magnetic Properties And Dimensional Stability

The Optimum heat treatment process of the1J50alloy magnetic properties anddimensional stability was studied in this paper. We also investigated the microscopicmechanism of the change in1J50alloy magnetic properties and dimensionalstability.Research shown that the optimum heat treatment process of1J50alloy wasannealing temperature at1225℃, heat preservation time for5h, fast-coolingtemperature at600℃. Under this condition, the magnetic properties reached thenational standard, the value of μmwas38.33mH/m, got an increase of79times theoriginal state; the value of BSwas1.503T, increased18.4%compared with primitivestate; the value of Hc is7.346A/m, decreased80.6%compared with primitive state;the average of the dimensional change was1.5×10^-7,98.2%lower than theoriginal sample, which was the optimal dimensional stability.The process analysis showed that the magnetic properties of the1J50alloymainly affected by the annealing temperature, and the dimensional stability of thematerial affected by three factors. As the annealing temperature increased, themagnetic properties of the alloy were greatly improved; dynamic dimension stabilityshowed was increased first and then decreased; micro-yield strength graduallydecreased. With the fast-cooling temperature increased, the magnetic properties ofthe alloy was improved but little change in the global aspect; dynamic dimensionstability was increased first and then decreased, achieved the best at600℃; whilemicro-yield strength showed a positive V-shaped trend.The residual stress numerical simulation of the caused in the1J50alloy heattreatment process was studied by Abaqus. By the numerical simulation, various ofthe1J50alloy residual stress and the evolution law of residual stress wereinvestigate on all types of heat treatment process.After heat treatment, the1J50alloy phase is still single phase γ（Fe,Ni） solidsolution, which was considered almost no phase transition occurs. Grain growth,grain boundary reduction, straight grain boundaries, the grains distributed evenlywere optimized organizational factors of the magnetic properities and dimensionalstability.Due to the heat treatment process was a thermal activation process, dislocationmotion and restructuring led to dislocation transition from disorder to orderly, thethermal effect made the dislocation develop to cell structure,and achieve arelatively stable dislocation configuration. With the continuous thermal effects, thedislocation density of the alloy get further decreased, the dislocation itself tend to the straight line and the formed the linear and low density dislocation configuration,the strain energy of the dislocation reduced, formed a stable dislocation network.The dynamic dimensional stability of the alloy increased and the dislocation densityreduced which caused the moving obstacle of domain wall reduced，so the magneticproperties improved. Research also shown that the low dislocation density was thereason that micro-yield strength increased.