Heat treatment annealing process for electromagnetic pure iron

Abstract

The invention relates to the technical field of heat treatment, in particular to a heat treatment annealing process of electromagnetic pure iron, which comprises the following steps of: 1, baking a vacuum furnace at the temperature of 1120 + / -10 DEG C for 3 hours, and putting cleaned parts on a furnace frame in the vacuum furnace at the interval of not less than 20mm; secondly, in the first annealing stage, the temperature of the part rises to 800 + / -10 DEG C along with the furnace temperature, the temperature rising rate is not larger than 400 DEG C / h, and heat preservation is conducted for 0.5 h; 3, annealing the second section, after heat preservation in the step 2 is finished, heating the part to 1100 + / -10 DEG C at the heating rate of not greater than 50 DEG C / h, and preserving heat for 4-5 hours; 4, annealing for the third stage, and after heat preservation in the step 3 is finished, cooling the part to 700 DEG C at the cooling rate of not greater than 50 DEG C / h; 5, annealing the fourth section, cooling to 700 DEG C, cooling the part to below 150 DEG C along with the furnace, and discharging and air-cooling; and step 6, checking the coercive force of the part. The technological process is simple and efficient, and the electromagnetic pure iron low in coercive force can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment, in particular to a heat treatment annealing process for electromagnetic pure iron. Background Art

[0002] As an important electromagnetic conversion element, electromagnetic pure iron has a wide range of applications in modern industry and science and technology. Coercivity is one of the key indicators to measure the performance of electromagnets. The size of the coercivity reflects whether the electromagnet can be quickly demagnetized after power failure, so as to have better response speed and energy efficiency. However, electromagnetic pure iron with low coercivity usually has high requirements for materials and manufacturing processes. Heat treatment annealing process is an important means to improve the coercivity of electromagnetic pure iron. Through reasonable heat treatment process, the coercivity of electromagnetic pure iron can be effectively reduced and the performance of electromagnetic pure iron can be improved. The main electromagnetic pure iron materials currently used are DT4 and DT4C. DT4 / DT4C is a high-quality steel with an iron content of more than 99.5% and a carbon content of less than 0.04%. This material has good electrical conductivity and magnetic properties, low coercivity, high magnetic permeability, and high thermal conductivity and mechanical strength.

[0003] At present, the heat treatment annealing process of DT4 electromagnetic pure iron usually refers to the contents of HB / Z5015-94 (Electromagnetic Pure Iron Heat Treatment Process Specification). In actual production, the annealing process parameters in this standard can only be used as a guide and need to be adjusted accordingly for different products. It is difficult for technical personnel to control the specific parameters, which will cause the performance of the electromagnetic pure iron to fail to meet the requirements. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides a heat treatment annealing process for electromagnetic pure iron.

[0005] The present invention discloses the following technical solution: a heat treatment annealing process for electromagnetic pure iron, comprising the following steps: Step 1: Bake the vacuum furnace at 1120±10℃ for 3 hours. After baking, place the cleaned parts on the furnace rack in the vacuum furnace. The interval between the parts should be no less than 20mm. Step 2: annealing stage 1: the parts are heated to 800±10℃ with the furnace temperature, the heating rate is ≯400℃ / h, and the temperature is kept for 0.5 hours; Step 3, annealing second stage, after the end of step 2, heat the parts to 1100±10℃ at a heating rate of ≯50℃ / h and keep warm for 4-5 hours; Step 4, annealing stage 3, after the end of step 3, the parts are cooled to 700°C at a cooling rate of ≯50°C / h; Step 5, annealing stage 4, after cooling to 700°C, the parts are cooled to below 150°C and air-cooled out of the furnace; Step six, check the coercive force of the parts. The coercive force of DT4 electromagnetic pure iron HC≯96 A / m, and the coercive force of DT4C electromagnetic pure iron HC≯32 A / m.

[0006] Furthermore, in step one, gasoline can be used to clean the parts, and the surface of the parts should be smooth, free of oil stains, burrs, scratches and other defects.

[0007] Furthermore, in the annealing process from step 2 to step 5, the vacuum furnace pressure is ≯1.3Pa.

[0008] Furthermore, during the inspection process of step six, a slight oxidation color is allowed on the surface of the part, but the part is not damaged.

[0009] Beneficial effects: Compared with the prior art, the heat treatment annealing process of electromagnetic pure iron of the present invention is simple and efficient, the process parameters are accurate and convenient for technicians to control, the processing difficulty is reduced, and electromagnetic pure iron with low coercive force can be obtained while maintaining good magnetic properties of electromagnetic pure iron. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a parameter schematic diagram of the heat treatment annealing process of electromagnetic pure iron of the present invention; DETAILED DESCRIPTION

[0011] like Figure 1 The parameter diagram shown in FIG. 1 is a heat treatment annealing process for electromagnetic pure iron, comprising the following steps: Step 1: Bake the vacuum furnace at 1120±10℃ for 3 hours. After baking, place the cleaned parts on the furnace rack in the vacuum furnace. The interval between the parts should be no less than 20mm. Step 2: annealing stage 1: the parts are heated to 800±10℃ with the furnace temperature, the heating rate is ≯400℃ / h, and the temperature is kept for 0.5 hours; Step 3, annealing second stage, after the end of step 2, heat the parts to 1100±10℃ at a heating rate of ≯50℃ / h and keep warm for 4-5 hours; Step 4, annealing stage 3, after the end of step 3, the parts are cooled to 700°C at a cooling rate of ≯50°C / h; Step 5, annealing stage 4, after cooling to 700°C, the parts are cooled to below 150°C and air-cooled. In steps 2 to 5, the vacuum furnace pressure is ≯1.3Pa; Step six, check the coercive force of the parts. The coercive force of DT4 electromagnetic pure iron HC≯96 A / m, and the coercive force of DT4C electromagnetic pure iron HC≯32 A / m.

[0012] Embodiment 1: Step 1: bake the vacuum furnace at 1120℃ for 3 hours, take two cleaned parts, DT4 and DT4C electromagnetic pure iron, with a size of φ10×200mm, and put them on the furnace rack in the vacuum furnace with a spacing of 20mm. After the parts are placed, adjust the vacuum furnace pressure to 1.3Pa; Step 2: The parts are heated to 800°C with a heating rate of 400°C / h and kept at this temperature for 0.5 hours; Step 3: After the heat preservation in step 2 is completed, the temperature of the parts is raised to 1100°C at a heating rate of 50°C / h and kept at this temperature for 4 hours; Step 4: After the heat preservation in step 3 is completed, the temperature of the parts is cooled to 700°C at a cooling rate of 50°C / h; Step 5: After the temperature drops to 700°C, the parts are cooled to below 150°C and then air-cooled out of the furnace; Step six, check the coercivity of the parts; The test results are as follows: the coercive force of DT4 electromagnetic pure iron is 93A / m, and the coercive force of DT4C electromagnetic pure iron is 32A / m, which meets the requirements.

[0013] Embodiment 2: Step 1: The vacuum furnace is baked at a temperature of 1130°C for 3 hours. Two cleaned parts, DT4 and DT4C electromagnetic pure iron, with a size of φ10×200mm, are placed on the furnace rack in the vacuum furnace with a spacing of 25mm between the parts. After the parts are placed, the vacuum furnace pressure is adjusted to 1.3Pa; Step 2: The parts are heated to 810°C with a heating rate of 400°C / h and kept at this temperature for 0.5 hours; Step 3: After the insulation in step 2 is completed, the temperature of the parts is raised to 1110°C at a heating rate of 50°C / h and kept at this temperature for 5 hours; Step 4: After the heat preservation in step 3 is completed, the temperature of the parts is cooled to 700°C at a cooling rate of 50°C / h; Step 5, annealing stage 4, after cooling to 700°C, the parts are cooled to below 150°C and air-cooled out of the furnace; Step six, check the coercivity of the parts; The test results are as follows: the coercive force of DT4 electromagnetic pure iron is 92A / m, and the coercive force of DT4C electromagnetic pure iron is 30A / m, which meets the requirements.

[0014] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A heat treatment annealing process for electromagnetic pure iron, characterized in that: The steps include: Step 1: Bake the vacuum furnace at 1120±10℃ for 3 hours. After baking, place the cleaned parts on the furnace rack in the vacuum furnace. The interval between the parts should be no less than 20mm. Step 2: annealing stage 1: the parts are heated to 800±10℃ with the furnace temperature, the heating rate is ≯400℃ / h, and the temperature is kept for 0.5 hours; Step 3, annealing second stage, after the end of step 2, heat the parts to 1100±10℃ at a heating rate of ≯50℃ / h and keep warm for 4-5 hours; Step 4, annealing stage 3, after the end of step 3, the parts are cooled to 700°C at a cooling rate of ≯50°C / h; Step 5, annealing stage 4, after cooling to 700°C, the parts are cooled to below 150°C and air-cooled out of the furnace; Step six, check the coercive force of the parts. The coercive force of DT4 electromagnetic pure iron HC≯96 A / m, and the coercive force of DT4C electromagnetic pure iron HC≯32 A / m.

2. The heat treatment annealing process of electromagnetic pure iron according to claim 1, characterized in that: In step one, gasoline can be used to clean the parts. The surface of the parts should be smooth, free of oil stains, burrs, scratches and other defects.

3. The heat treatment annealing process of electromagnetic pure iron according to claim 1, characterized in that: In the annealing process from step 2 to step 5, the vacuum furnace pressure is ≯1.3Pa.

4. The heat treatment annealing process of electromagnetic pure iron according to claim 1, characterized in that: During the inspection process in step six, slight oxidation color is allowed on the surface of the parts, but the parts are not damaged.

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