TWI403590B - The low temperature process of electromagnetic steel - Google Patents

Abstract

A low temperature process for an electromagnetic steel sheet provided by the invention firstly produces silicon steel slab containing nailing element free in the composed constituent through the preparation step. The silicon steel slab then is hot-rolled in the rolling step. The board material with a predetermined thickness is obtained after performing the annealing, acid washing and cold rolling. The board material is performed with re-crystallizing and annealing at 700 to 950 degrees Celsius to control the crystal grain size of the board material at 15 &mgr; to 30 &mgr; to form a semi product. The process further comprises coating magnesium oxide after the re-crystallization annealing step, and a high temperature annealing step in a pure hydrogen atmosphere to obtain the electromagnetic steel sheet having a growth grain size less than 0.5 cm. By controlling the grain size to obtain the appropriate re-crystallization boundary energy so that the re-crystallization can be carried out completely, high quality electromagnetic steel sheet can be obtained through an energy saving and low temperature process.

Description

Low temperature process of electromagnetic steel sheet

The invention relates to a method for manufacturing an electromagnetic steel sheet, in particular to a low temperature process for an electromagnetic steel sheet.

The high magnetic flux and low iron loss of the electromagnetic steel sheet are expressed in the orientation of {110}<001>, the grain growth and alignment in the so-called Goss Orientation. Therefore, the industry is producing electromagnetic steel. In the film, the grain can grow steadily along the orientation of {110}<001>, which is the primary target for the production of electromagnetic steel sheets.

In the existing electromagnetic steel sheet process, most of the steel embryos need to be reheated to above 1300 ° C to solidify the precipitates, and then precipitated in the subsequent hot rolling stage to achieve excellent precipitation grain boundary segregation effect and good secondary re- Crystallization and magnetism. Under the premise of energy saving, a few are carried out under medium and low temperature (not more than 1200 ° C), and sequentially include a preparation step, a rolling step, a recrystallization annealing step, and a full hydrogen high temperature annealing step.

First, the preparation step is performed to produce a bismuth steel embryo comprising carbon, bismuth, aluminum, nitrogen, manganese, sulfur, phosphorus, tin, copper, selenium, tellurium, chromium, molybdenum, nickel and a balance amount of iron, wherein Elements such as phosphorus, tin, copper, selenium, tellurium, chromium and molybdenum, which are known as grain boundary segregation elements in the industry, can control the grain size after subsequent steps by precisely controlling the composition ratio of the segregation elements in the grain boundary. Further, an electromagnetic steel sheet to be prepared is obtained.

Then, the rolling step is performed, and the steel sheet is hot rolled at a temperature ranging from 1100 to 1200 ° C, and then at a temperature ranging from 1100 to 1200 ° C. An annealing pickling is performed, and a cold rolling is performed to obtain a steel material having a predetermined thickness.

Then, the recrystallization annealing step is performed, and recrystallization annealing is performed in a temperature range of 800 ° C to 950 ° C to control the average grain size of the steel material to be less than 10 μm, and then a layer of magnesium oxide is coated on the steel material to obtain a semi-finished steel sheet.

Finally, the all-hydrogen high-temperature annealing step is performed, and the semi-finished steel sheet is subjected to high-temperature annealing in a hydrogen atmosphere, and the composition of the grain boundary segregation elements and the control of the average grain size in the recrystallization annealing step are less than 10 μm. The grain growth direction of the secondary recrystallization in the grain is suppressed, and the crystal grain can be stably grown along the orientation of {110}<001> to obtain an electromagnetic steel sheet.

It can be seen from the above description that the current electromagnetic steel sheet process is a process in which the segregation elements at the grain boundary are melted and precipitated at a high temperature, thereby effectively suppressing other growth directions of the crystal grains, thereby allowing the crystal grains to follow the {110 } The orientation of <001> is steadily growing. Therefore, a large amount of energy must be used for heating throughout the process. The steel is first recrystallized at 800 ° C to 950 ° C to control the average grain size to be less than 10 μm, and then the high temperature annealing is performed. The grain growth can complete the manufacture of electromagnetic steel sheets, and the production cost is extremely high. In addition, the proportion of segregation elements in the grain boundary is also limited by the extremely strict composition range, and each steelmaking method has different manufacturing methods. Ingredients, and the amount of steel in a furnace, in order to accurately control the composition of the grain boundary segregation elements of such a very strict composition range, must consume extremely large human and material costs.

Accordingly, it is an object of the present invention to provide a low temperature process for electromagnetic steel sheets that saves process cost.

Therefore, the low temperature process of the electromagnetic steel sheet of the present invention comprises a preparation step, a rolling step, a recrystallization annealing step, and a full hydrogen high temperature annealing step.

In the preparation step, a steel sheet containing no grain boundary segregation elements in the composition is produced; in the rolling step, the steel sheet is subjected to hot rolling after annealing and pickling at a temperature ranging from 800 ° C to 1200 ° C, and then After the cold rolling treatment, a plate having a predetermined thickness is obtained; the recrystallization annealing step is performed by recrystallization annealing at a temperature ranging from 700 ° C to 950 ° C, so that the average grain size of the plate is between 15 μm and 30 μm, and then The plate is coated with a predetermined thickness of magnesium oxide to obtain a semi-finished steel sheet; the all-hydrogen high temperature annealing step is to subject the semi-finished steel sheet to high temperature annealing under a hydrogen atmosphere to obtain the electromagnetic steel sheet.

The invention has the advantages of removing the addition of grain boundary segregation elements from the source, and obtaining a suitable recrystallized grain boundary energy in combination with a low-temperature recrystallization annealing control to obtain large-sized crystal grains, thereby causing crystal grains during high-temperature high-temperature annealing. It can grow stably into large-sized crystal grains along the orientation of {110}<001>, and then, in the premise of low-temperature energy saving, simple and stable production of electromagnetic steel sheets with good electromagnetic properties.

The foregoing and other technical contents, features, and advantages of the present invention will be described in the following detailed description of a preferred embodiment with reference to the drawings. Clear presentation.

Referring to Figure 1, a preferred embodiment of the low temperature process of the electromagnetic steel sheet of the present invention comprises a preparation step 11, a rolling step 12, a recrystallization annealing step 13, and a full hydrogen high temperature annealing step 14.

First, the preparation step 11 is carried out to produce a composition comprising 0.03 wt% carbon, 3.1 wt% bismuth, 0.15 wt% manganese, 0.005 wt% sulfur, 0.04 wt% aluminum, and 0.005 wt% nitrogen and balance. Iron iron steel, and wherein the steel embryo does not additionally add grain boundary segregation elements such as phosphorus, tin, copper, selenium, tellurium, chromium or molybdenum, by adding no grain boundary segregation elements in the steel The utility model can greatly reduce the cost of the raw material cost, and reduce the labor and material cost which are required to accurately control the composition of the grain boundary segregation element, thereby achieving the purpose of reducing the production cost and improving the production yield; Yes, in the refining process of the raw material of the antimony steel, the intrinsic material contains inevitable impurities, and such impurities may still contain the above-mentioned grain boundary segregation elements, but the content thereof is extremely small, which should not be sufficient. It affects the results of this embodiment and should not be limited to this.

Then, the rolling step 12 is performed, and the slab is reheated to a temperature range of 1100 ° C to 1200 ° C, and hot rolled in a subsequent cooling stage to reduce the thickness of the bismuth steel to 2.3 mm, and then at 800 ° C to 1200 ° C. The temperature range is subjected to annealing and pickling, and after one cold rolling treatment, a sheet having a predetermined thickness is obtained, which is 0.3 mm in this example.

Since the grain boundary segregation element is not added in the preparation step 11, in the rolling step 12, the hot rolled steel sheet can be recovered at a lower reheat temperature of the steel (about 1050 ° C). Recrystallization to achieve energy saving In addition, the primary cold rolling in this step causes a large amount of deformation of the niobium steel without the addition of grain boundary segregation elements, so that the grain can be rapidly accumulated by the strain energy generated after the deformation, thereby providing the crystal grains in the subsequent step. There is sufficient driving force to grow when recrystallization is performed.

Next, the recrystallization annealing step 13 is carried out, in a temperature range of 700 ° C to 950 ° C, a Dew point of 60 ° C, and a 50% hydrogen gas and a 50% nitrogen atmosphere, after cold rolling. The sheet is subjected to recrystallization annealing, so that the average grain size of the sheet is grown to 15 μm to 30 μm throughout the recrystallization annealing process, and then the sheet is coated with a layer of magnesium oxide having a thickness of about 2 g/m ² to obtain a semi-finished steel sheet; Preferably, the recrystallization annealing temperature is 800 ° C. At this time, the average particle size of the steel sheet can be controlled to 20 μm.

In the recrystallization annealing step 13 described above, since there is no hindrance of grain boundary segregation elements in the composition of the sheet material, the strain accumulated in the rolling step 12 can be utilized at a lower temperature to enable the crystal in the sheet. The particles can grow in a large number of large-sized grains at the time of recrystallization, thereby reducing the generation of grain boundaries and lowering the grain boundary energy.

Finally, the all-hydrogen high-temperature annealing step 14 is performed, and the semi-finished steel sheet is subjected to high-temperature annealing in a two-step heating mode under a hydrogen atmosphere, and the magnesium oxide layer is removed by annealing at a lower temperature (about 650 ° C) in the first stage. Part of the hydrate, and then the temperature rise process causes the grains to undergo secondary recrystallization growth, and then in the second stage, a higher temperature (about 1200 ° C) heating method is used to further grow the crystal grains and purify the impurity elements in the steel sheet. At the same time, in the process, aluminum and nitrogen in the composition of the enamel steel will form aluminum nitride between the grains. The grain growth direction is restricted, and the crystal grains can be stably grown to an angle of not less than 0.5 cm along the orientation of {110}<001> to obtain an electromagnetic steel sheet having excellent magnetic properties.

Referring to FIG. 2, FIG. 2 is a metallographic structure of a primary recrystallized grain of the semi-finished steel sheet obtained by the above-mentioned embodiment in the recrystallization annealing step 13. The metallographic structure shows that the average grain size of the primary recrystallization is 20 μm, and once. The recrystallized grain size distribution is uniform, and few fine crystal grains exist between the crystal grains, indicating that the crystal grains are not affected by the grain boundary segregation elements and exhibit uniform and large sizes.

Referring to FIG. 3, FIG. 3 is a metallographic structure of the electromagnetic steel sheet obtained after all the steps are completed. In the metallographic structure, the secondary recrystallized grains are extremely intense compared with the primary recrystallized grains of FIG. The size is increased, and the average grain size is 1.5cm, which shows that the grain does grow stably along {110}<001>; and after the magnetic flux and iron loss are measured, the magnetic flux of the electromagnetic steel sheet is 1.9 tes. Tesla, and the iron loss value is 1.04 watts per kilogram, which proves that the low-temperature process of the electromagnetic steel sheet of the present invention described above can indeed produce an electromagnetic steel sheet having good magnetic properties.

In addition, in the above-mentioned all-hydrogen high-temperature annealing step, after the grain of the semi-finished steel sheet is grown to not less than 0.5 cm at a high temperature, the semi-finished steel sheet may be additionally leveled to reduce the surface corrugation height of the steel sheet. An additional layer of insulating material is applied to produce electromagnetic steel sheets that meet customer specifications.

It can be seen from the above description that the low temperature process of the electromagnetic steel sheet of the present invention is completely different from the current production process of the electromagnetic steel sheet, but is modified to cancel the addition of crystal. The method of segregating elements in the boundary first reduces the huge manpower and material cost that is required to accurately control the addition of segregation elements in the micro-grain boundary in the past, and then, by adding the segregation elements at the grain boundary, it can be rolled in the next In the extension step and the recrystallization annealing step, the environment in which the high temperature is heated is not required to segregate the element at the solid solution grain boundary, so that the grain can be made to be along the {110}<001> at a low temperature under the condition of low energy saving. The orientation is stably arranged and grown, and the effect of producing an electromagnetic steel sheet having good magnetic properties under the premise of low temperature and energy saving can truly achieve the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

11‧‧‧Preparation steps

12‧‧‧Rolling steps

13‧‧‧Recrystallization annealing step

14‧‧‧All hydrogen high temperature annealing step

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing a preferred embodiment of the low temperature process of the electromagnetic steel sheet of the present invention; and Figure 2 is a metallographic view showing the implementation of a preferred embodiment of the low temperature process of the electromagnetic steel sheet of the present invention. The metallographic structure of the semi-finished steel sheet obtained after the recrystallization annealing step; and FIG. 3 is a metallographic diagram illustrating the implementation of a preferred embodiment of the low temperature process of the electromagnetic steel sheet of the present invention after a high hydrogen high temperature annealing step The metallographic structure of the obtained electromagnetic steel sheet.

11‧‧‧Preparation steps

12‧‧‧Rolling steps

13‧‧‧Recrystallization annealing step

14‧‧‧All hydrogen high temperature annealing step

Claims (4)

A low-temperature process for an electromagnetic steel sheet, comprising: a preparation step of producing a steel sheet embryo having no segregation element at a grain boundary in a composition; and a rolling step of hot rolling the steel sheet at a temperature ranging from 800 ° C to 1200 ° C After annealing and pickling, and then cold rolling, a sheet having a predetermined thickness is obtained; a recrystallization annealing step is performed by recrystallization annealing at a temperature ranging from 700 ° C to 950 ° C to make the average grain size of the sheet 15μm~30μm, and then coating a plate with a predetermined thickness of magnesium oxide to obtain a semi-finished steel plate; and a full hydrogen high temperature annealing step, the high-temperature annealing of the semi-finished steel plate under a full hydrogen atmosphere to obtain the electromagnetic steel sheet. According to the low temperature process of the electromagnetic steel sheet according to claim 1, wherein the grain boundary segregation element not included in the preparation step refers to phosphorus, tin, copper, selenium, tellurium, chromium, or molybdenum. According to the low temperature process of the electromagnetic steel sheet according to the second aspect of the patent application, in the high hydrogen high temperature annealing step, the grain of the semi-finished steel sheet is grown to not less than 0.5 cm at a high temperature to obtain the electromagnetic steel sheet. . According to the low temperature process of the electromagnetic steel sheet according to the third aspect of the patent application, in the high hydrogen high temperature annealing step, after the grain growth of the semi-finished steel sheet is increased to not less than 0.5 cm at a high temperature, the semi-finished steel sheet is further The electromagnetic steel sheet is obtained by applying a layer of insulating material after flattening.