阅读说明：本技术 一种高磁感取向硅钢渗氮退火的生产方法及其产品 (High magnetic induction grain-oriented silicon steel nitriding annealing production method and product thereof ) 是由 张波 于 2018-06-14 设计创作，主要内容包括：本发明的目的是提供一种高磁感取向硅钢渗氮退火的生产方法,用于生产低温高磁感取向硅钢铁损值达到0.90～0.95W/kg的成品。本发明高磁感取向硅钢渗氮退火的生产方法为：中温渗氮,渗氮温度为800～850℃,与脱碳温度一致,渗氮时间为10～50s,渗氮介质为氨气,流量为5～6m<Sup>3</Sup>/h,压力为25～30KPa,同时炉内通入氮氢混合保护气。渗氮值工艺标准范围为150～210ppm。(3 The invention aims to provide a production method of high magnetic induction grain-oriented silicon steel nitriding annealing, which is used for producing a finished product with a low-temperature high magnetic induction grain-oriented silicon steel iron loss value of 0.90-0.95W/kg.)

1. The nitriding annealing step is medium-temperature nitriding, the nitriding temperature is 800-850 ℃, the nitriding temperature is consistent with the decarburization temperature, the nitriding time is 10-50 s, the nitriding medium is ammonia gas, the flow rate is 5-6 m ³/h, the pressure is 25-30 KPa, meanwhile, nitrogen-hydrogen mixed protective gas is introduced into the furnace, and the process standard range of the nitriding value is 150-210 ppm.

2. The production method according to claim 1, characterized in that: before the medium-temperature nitriding step, a decarburization step is carried out, wherein the decarburization temperature is 800-850 ℃, the dew point is 40-60 ℃, the decarburization time is 80-400 s, and wet nitrogen and hydrogen protective gas is introduced into the furnace.

3. The production method according to claim 1, characterized in that the nitriding annealing step comprises nitriding at 800 ℃ for 10s at a flow rate of 5m ³/h with ammonia as a nitriding medium under a pressure of 25KPa while introducing a mixed protective gas of nitrogen and hydrogen into the furnace, wherein the standard range of the nitriding value is 157 ppm.

4. The production method according to claim 1, characterized in that the nitriding annealing step comprises the steps of nitriding at 850 ℃ for 50s at a flow rate of 6m ³/h with ammonia as a nitriding medium under a pressure of 30KPa while introducing a nitrogen-hydrogen mixed protective gas into the furnace, wherein the process standard range of the nitriding value is 210 ppm.

5. The production method according to claim 1, characterized in that the nitriding annealing step comprises the steps of nitriding at 830 ℃ for 30s at a flow rate of 5.5m ³/h with ammonia as a nitriding medium under a pressure of 28KPa while introducing a nitrogen-hydrogen mixed protective gas into the furnace, wherein the process standard range of the nitriding value is 181 ppm.

6. High magnetic induction grain-oriented silicon steel produced by the production method according to any one of claims 1 to 5.

Technical Field

the invention belongs to the field of metal material manufacturing and processing, and particularly relates to a production method for high magnetic induction grain-oriented silicon steel nitriding annealing and a product thereof.

background

From the development trend of the transformer industry, the transformer is developed towards high capacity, high parameter, energy saving and intelligentization, the implementation strategy of pushing the energy-saving transformer is proposed in 2015 by the national power industry, the S9 type transformer is definitely eliminated step by step, the S13 type transformer is used in large quantity, and particularly the requirement on high magnetic induction oriented silicon steel is obviously increased.

The iron loss and the magnetic induction of the finished high magnetic induction oriented silicon steel product are closely related to the whole process production process, wherein the nitriding annealing process is particularly critical. At present, nitriding production methods of high magnetic induction oriented silicon steel mainly comprise two methods: high temperature and low temperature nitriding. High-temperature nitriding: nitriding at 850-900 ℃; low-temperature nitriding: nitriding at 700-800 ℃. The two nitriding modes both require long furnace sections, the equipment investment is large, the production energy consumption is large, and the operation cost is high.

A method for producing high magnetic induction oriented silicon steel strips through three-stage normalization (application No. 2012105199065, publication No. CN103074476, publication No. 2014.02.26) disclosed in chinese patent application discloses a method for producing high magnetic induction oriented silicon steel strips, which comprises the following steps: 1) after smelting and casting, heating the casting blank to 1100-1250 ℃; 2) carrying out hot rolling: rolling to be 6-15.3 times as thick as the finished product; 3) coiling, wherein the coiling temperature is controlled to be 500-700 ℃; 4) normalizing annealing is carried out in three sections: the temperature of the first stage is controlled to be 950-1150 ℃, the temperature of the second stage is controlled to be 1050-950 ℃, and the temperature of the third stage is controlled to be 950-800 ℃; 5) performing one-time cold rolling to the thickness of a finished product, and performing aging rolling at 130-250 ℃ during cold rolling; 6) performing decarburization annealing in a wet N2+ H2 atmosphere, controlling the decarburization annealing temperature at 800-900 ℃ and the decarburization annealing time at 60-240 seconds; 7) nitriding and annealing are carried out, the nitriding and annealing temperature is controlled to be 750-980 ℃, the nitriding and annealing atmosphere is N2+ H2+ NH3, and the content of NH3 accounts for 1-30% of the total gas volume percentage; 8) carrying out high-temperature annealing at 700-1200 ℃ for at least 2 hours; and in the annealing temperature range of 750-1100 ℃, the content of N2 in the atmosphere by volume percent is not lower than 15 percent; and the weight percentage content of N in the steel strip is controlled to be 0.007-0.03%, and the weight percentage content of Als is controlled to be 0.02-0.035%. And 7) nitriding annealing is carried out, the nitriding annealing temperature is controlled to be 750-980 ℃, the nitriding annealing atmosphere is N2+ H2+ NH3, and the content of NH3 accounts for 1-30% of the total gas volume percentage. The high magnetic induction oriented silicon steel of the nitriding method in the prior art has high iron loss value, and the quality of the high magnetic induction oriented silicon steel can not be ensured.

Disclosure of Invention

The invention aims to provide a production method for nitriding and annealing high-magnetic-induction oriented silicon steel, which is used for producing low-temperature high-magnetic-induction oriented silicon steel, wherein the iron loss value of the finished product reaches 0.90-0.95W/kg. The production process is implemented according to the steps of decarburization annealing → nitriding, the nitriding method can be referred to as a medium-temperature nitriding process for short, and the specific implementation scheme is as follows:

1. a decarbonization section: the decarburization temperature is 800-850 ℃, the dew point is 40-60 ℃, the decarburization time is 80-400 s, and wet nitrogen and hydrogen protective gas is introduced into the furnace;

2. And in the nitriding section, medium-temperature nitriding is carried out, the nitriding temperature is 800-850 ℃, the temperature is consistent with the decarburization temperature, the nitriding time is 10-50 s, the nitriding medium is ammonia gas, the flow is 5-6 m ³/h, the pressure is 25-30 KPa, meanwhile, nitrogen-hydrogen mixed protective gas is introduced into the furnace, and the technological standard range of the nitriding value is 150-210 ppm.

³In the specific embodiment, when the high magnetic induction oriented silicon steel is produced by adopting the high magnetic induction oriented silicon steel nitriding annealing, other process steps are the same as those of the prior art, and the key point of the invention is improvement of the nitriding step, so the high magnetic induction oriented silicon steel is produced by the steps of 1) smelting and casting, heating the casting to 1100-1250 ℃, 2) hot rolling to 6-15.3 times the thickness of a finished product, 3) coiling, controlling the coiling temperature to be 500-700 ℃, 4) carrying out normalizing annealing in three stages, namely, controlling the first stage temperature to be 950-1150 ℃, controlling the second stage temperature to be 1050-950 ℃, controlling the third stage temperature to be 950-800 ℃, 5) carrying out primary cold rolling to the thickness of the finished product, adopting a 130-250 ℃ aging rolling mode during cold rolling, 6) carrying out decarburization annealing in a wet N2+ H2 atmosphere, controlling the decarburization annealing temperature to be 800-900 ℃, carrying out decarburization annealing for 60-240 seconds, 7) carrying out nitriding, carrying out medium temperature nitriding, controlling the decarburization annealing to be 800-800 ℃, being consistent with the decarburization temperature and the decarburization temperature, and being 10-10H, and introducing ammonia gas with the nitriding protection pressure of 50-10 ppm, compared with the nitriding pressure of the nitriding process of the high temperature, the nitriding process of the nitriding temperature of the high-35-500:

1. The nitriding temperature is 800-;

2. The nitriding time is shortest (10-20s), and is reduced by 2-3 times compared with the high-temperature nitriding time and the high-temperature nitriding time, so that the production efficiency is improved;

3. Under the same pressure of 25-30 KPa, the flow of ammonia gas for nitriding is the lowest, the flow of ammonia gas is only required to be 5-6 m3/h, the flow is reduced by 3-10 times compared with the flow of high-temperature and low-temperature nitriding, the corrosion effect on equipment such as a furnace roller, a heating resistance belt and a thermocouple in a nitriding section is smaller, and the service life of the equipment is prolonged by 2-3 times;

compared with the high-temperature nitriding and low-temperature nitriding technologies, the method has the following economic benefits:

In the high-temperature nitriding method, two heating sections are arranged in front of a nitriding section so as to raise the temperature of a plate to 850-950 ℃ and then enter the nitriding section for nitriding; the low-temperature nitriding method needs to increase a pipe cooling section after the two soaking sections so as to reduce the plate temperature to 700-800 ℃ and enter the nitriding section for nitriding; the invention is medium temperature nitriding, namely nitriding at the decarburization temperature, so that the decarbonized steel directly enters two soaking sections for nitriding, and the method has the advantages of few furnace sections, short furnace, small equipment investment, small production energy consumption and low operation cost.

Detailed Description