CN1410580A - Cold rolling electromagnetic pure iron plate having very low coercive force and production method thereof - Google Patents

Abstract

The invention provides a cold-rolled electromagnetic pure iron strip with extremely low coercive force, the composition weight percent of which is: C≤0.010%, Si: 0.10-0.03%, Mn: 0.1%-0.5%, Al≤0.005% , P ≤ 0.05%, S ≤ 0.01%, N ≤ 0.005%, O ≤ 0.02%, and the rest is iron; the production method is: hot rolling the continuous casting slab with the above composition according to the following system: heating at 1000 ° C ~ 1250 ° C And 750 ℃ ~ 900 ℃ final rolling, the cold rolling deformation is controlled at more than 60%, the cold rolled plate is continuously annealed at 600 ℃ ~ 800 ℃ to make the finished plate, the finished plate is 800 ℃ ~ 900 ℃ × 2h, non-oxidizing atmosphere Magnetic annealing produces a cold-rolled electromagnetic pure iron strip with extremely low coercive force, which has the characteristics of low production cost and good blanking performance.

Description

Cold-rolled electromagnetic pure iron strip with extremely low coercive force and production method thereof

technical field

The invention relates to a cold-rolled electromagnetic pure iron strip, in particular to a cold-rolled electromagnetic pure iron strip with extremely low coercive force and a production method thereof.

Background technique

Cold-rolled electromagnetic pure iron strip with extremely low coercive force is usually used in electromagnetic relays, magnetic shielding and DC motors and other equipment.

The manufacturing method of extremely low coercive force cold-rolled electromagnetic pure iron strip mainly has the following aspects:

The manufacturing method with higher carbon content and higher content of Al (0.15%-0.5%) and silicon (0.20%) stipulated in GB6985-86 has the disadvantage of high cost and requires the user to perform decarburization during magnetic annealing. Otherwise, the magnetic property deteriorates and magnetic aging occurs. Due to the high carbon content and silicon content, the pure iron plate has high hardness, poor punchability, and insufficient bright bands on the sheared section, which may easily cause the aging of the electromagnetic relay.

The method of the ultra-low carbon aluminum killed steel disclosed in JP-P-5-247604 by smoothing (critical reduction). The purpose of critical leveling is to coarsen the grains of the pure iron strip during magnetic annealing, so as to achieve the purpose of extremely low coercive force. The disadvantage of this method is that due to the large critical leveling amount, it is easy to cause strain aging, and the hardness of the pure iron plate increases rapidly after leaving the factory, which makes it difficult for users to punch. If the pure iron strip is annealed in a bell furnace, due to the non-uniform grains in the long direction of the pure iron strip, the coercive force on the entire pure iron strip after magnetic annealing of the finished product will be uneven and the performance will be unstable.

A high-purity pure iron production method produced by a Japanese special steel company, characterized by ultra-low carbon (<0.005%), ultra-low aluminum (<0.001%), very low silicon (<0.03%), and general content of manganese (0.2%) and low phosphorus (<0.02%). The disadvantage is that because the deoxidizing elements such as aluminum and silicon are very low, the oxygen content in molten steel is very high during smelting, and the increase of oxidized inclusions will have an adverse effect on the performance of the final product. At the same time, the high oxygen content also makes continuous casting difficult and the cost increases. It is quite difficult to smelt to obtain a slab with a low oxygen content.

In patent 98103523.X (the patentee is the applicant), a production method of cold-rolled pure iron plate containing higher phosphorus and silicon in pure iron plate is provided. cause device aging.

Contents of the invention

In view of the existing situation, the purpose of the present invention is to provide a cold-rolled electromagnetic pure iron strip with low production cost, good blanking performance, and extremely low coercive force and a production method thereof.

In order to achieve the above object, the cold-rolled electromagnetic pure iron strip with extremely low coercive force of the present invention:

Its composition weight percentage is: C≤0.010%, Si: 0.10～0.03%, Mn: 0.1%～0.5%, Al≤0.005%, P≤0.05%, S≤0.01%, N≤0.005%, O≤0.02% , and the rest is iron.

The production method of cold-rolled electromagnetic pure iron strip with extremely low coercive force is:

The composition is C≤0.010%, Si: 0.10～0.03%, Mn: 0.1%～0.5%, Al≤0.005%, P≤0.05%, S≤0.01%, N≤0.005%, O≤0.02%, and the rest are Iron; the continuous casting slab with the above composition is hot-rolled according to the following system: heating at 1000°C to 1250°C and final rolling at 750°C to 900°C, the amount of cold rolling deformation is controlled above 60%, and the cold rolled plate is heated at 600°C to 800°C Continuous annealing is used to produce a finished sheet, which can be magnetically annealed at 800°C to 900°C for 2h (in a non-oxidizing atmosphere) to obtain a cold-rolled electromagnetic pure iron strip with a coercive force Hc≤40A/m.

Principle of the present invention is introduced as follows:

C: 0.010% or less. C exceeding 0.010% is an element that strongly hinders grain growth, increases coercive force, and causes magnetic aging.

Si: Si 0.10 to 0.03%. If the amount of Si exceeds 0.10%, the magnetic induction will decrease, and if it is less than 0.03%, it will make it difficult to deoxidize during smelting, and the increase of the oxygen content will be harmful to the magnetism of the final product.

Mn: 0.1% to 0.5%. Mn is an element that improves the surface state of pure iron plates and reduces hot brittleness. If it is less than 0.1%, the effect is not good, and if it is higher than 0.5%, the hardness of pure iron plates will increase and the workability will be poor.

Al: 0.005% or less. Exceeding 0.005% will increase the amount of AlN precipitation, the growth of pure iron plate grains will not be sufficient during magnetic annealing, and the coercive force will increase, which will not meet the target requirement of 40A/m or less.

P: 0.05% or less. More than 0.05% will increase the hardness of the pure iron plate, the workability is not good, and at the same time, the bright band on the shear surface is not enough, which will accelerate the aging of the relay.

S: 0.01% or less. Exceeding 0.01% will greatly increase the precipitation of Si compounds such as MnS, strongly hinder the growth of grains, and increase the coercive force.

N: 0.005% or less. Exceeding 0.01% will greatly increase the precipitation of AlN and other nitrides, strongly hinder the growth of grains, and increase the coercive force.

O: 0.02% or less. Exceeding 0.02% will greatly increase the amount of oxidized inclusions, strongly hinder the growth of grains, and at the same time increase the demagnetization field caused by inclusions and increase the coercive force.

The above requirements on the composition are important conditions for achieving extremely low coercive force. The requirements of the hot rolling system are mainly to ensure the smooth implementation of the hot processing process, while minimizing the precipitation of MnS and AlN.

SRT: 1000℃～1250℃. If the temperature is lower than 1000°C, the hot continuous rolling process cannot be completed, and the final rolling and coiling temperature cannot be guaranteed. If the temperature is higher than 1250°C, the precipitation of MnS and AlN solid solution and hot rolling process will increase, and the grain growth resistance will increase.

FDT; 750℃～900℃. If it is lower than 750°C, it will be difficult to complete hot rolling and coiling. If it is higher than 900°C, the hot-rolled sheet will undergo phase transformation during cooling, and the crystal grains will become smaller, which is not good for the magnetic properties of the final product.

The control of cold rolling deformation and annealing temperature mainly makes the pure iron sheet have good blanking processability. If the deformation amount is less than 60%, the grain growth of the pure iron plate after magnetic annealing will be insufficient, and the coercive force will increase. Soft annealing temperature lower than 600°C and higher than 800°C will not get better hardness and processability.

Since the steel contains a certain amount of silicon, the oxygen content in the steel can be reduced, which is beneficial to the implementation of large-scale production, and the cost is relatively low.

Detailed ways

Example:

Make the cold-rolled electromagnetic pure iron strip of the present invention by composition (surplus being Fe) shown in table 1, make the product of the present invention through continuous casting, hot rolling, cold rolling and annealing. The hot rolling degree, cold rolling degree, softening annealing temperature, magnetic annealing temperature and plate thickness are shown in Table 2, and the coiling temperature of the embodiment of the present invention is 700°C. Table 2 shows the coercive force of the obtained cold-rolled electromagnetic pure iron strip with extremely low coercive force of the present invention and the coercive force of the comparative example. It can be seen from Table 2 that the coercivity of the cold-rolled electromagnetic pure iron strip of the present invention is much smaller than that of the comparative example.

The composition (unit weight %) of table 1 embodiment and comparative example Example C P Si N S mn Al o Example 1 0.0019 0.015 0.060 0.0019 0.0071 0.46 0.001 0.0180 Example 2 0.0050 0.011 0.080 0.0017 0.0039 0.25 0.001 0.0152 Example 3 0.0080 0.035 0.040 0.0030 0.0020 0.15 0.003 0.0105 Comparative example 1 0.0020 0.073 0.150 0.0014 0.0046 0.24 0.001 0.0165 Comparative example 2 0.0018 0.014 0.008 0.0019 0.0043 0.24 0.001 0.0218

Table 2 Production process and measurement results Example Hot rolled SRT℃ Hot rolled FDT℃ softening annealing temperature Magnetic annealing temperature Cold rolling reduction % Plate thickness mm HcA/m GB6985-86 comparison Example 1 1050 800 700 800 71 1.0 19 DT4C Example 2 1150 830 750 850 75 1.0 20 DT4C Example 3 1200 860 650 870 65 1.0 26 DT4C Comparative example 1 1170 850 750 850 75 1.0 36 DT4E Comparative example 2 1140 820 650 870 71 1.0 60 DT4A

Claims (2)

1. A cold-rolled electromagnetic pure iron strip with extremely low coercive force, characterized in that: its composition weight percentage is: C≤0.010%, Si: 0.10-0.03%, Mn: 0.1%-0.5%, Al ≤0.005%, P≤0.05%, S≤0.01%, N≤0.005%, O≤0.02%, and the rest is iron. 2. A production method of cold-rolled electromagnetic pure iron strip with extremely low coercive force, characterized in that: C≤0.010%, Si: 0.10-0.03%, Mn: 0.1%-0.5%, Al≤0.005% , P ≤ 0.05%, S ≤ 0.01%, N ≤ 0.005%, O ≤ 0.02%, and the rest is iron. The continuous casting slab with the above components is hot-rolled according to the following system: heating at 1000°C to 1250°C and heating at 750°C to 900°C ℃ final rolling, the cold rolling deformation is controlled above 60%, and the cold-rolled sheet is continuously annealed at 600°C to 800°C to make a finished sheet, and the finished sheet is magnetically annealed in a non-oxidizing atmosphere at 800°C to 900°C for 2 hours.