Technological method for reducing edge breakage defect of copper-containing oriented silicon steel

Abstract

The invention discloses a process method for reducing the edge breakage defect of copper-containing oriented silicon steel. The process method comprises the following steps: hot rolling raw materials comprise the following chemical components in percentage: 0.025-0.045% of C, 3.00-3.60% of Si, 0.16-0.24% of Mn, 0.012-0.024% of Al s, 0.40-0.55% of Cu, less than or equal to 0.020% of P, less than or equal to 0.020% of S and 0.0070-0.0120% of N; the oriented silicon steel continuous casting billet is subjected to hot charging and hot delivery, and the hot charging temperature is higher than 400 DEG C; the tapping temperature is lower than 1310 DEG C; the in-furnace time of the second heating section and the soaking section is controlled to be smaller than 150 min, and the total in-furnace time is controlled to be smaller than 320 min; the finish rolling temperature of a finishing mill is 930-980 DEG C; and the coiling temperature is 530-590 DEG C. According to the invention, the waste reduction rate caused by the defect is greatly reduced to a controllable range below 0.3% from 3.7% before improvement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper-containing oriented silicon steel production, and particularly relates to a process method for reducing edge scrap defects of copper-containing oriented silicon steel. BACKGROUND

[0002] Copper-containing oriented silicon steel is a key soft magnetic material mainly used for manufacturing transformer cores. Its magnetic properties (such as iron loss and magnetic induction intensity) directly determine the no-load loss and energy efficiency level of the transformer. With the continuous improvement of global energy efficiency standards, users have extremely strict requirements for the magnetic properties and apparent quality of oriented silicon steel. Any surface defect not only affects the appearance of the product, but also seriously deteriorates its magnetic properties, resulting in a decrease in the energy efficiency level of the transformer.

[0003] In the production process of copper-containing oriented silicon steel, the surface quality of the hot-rolled strip steel is the basis for determining the quality of the final cold-rolled product. The edge region of the hot-rolled strip steel is a sensitive area for surface defects due to uneven distribution of temperature field and stress field. In production practice, the edge "scrap" defect (also known as "cookie layer" defect) is one of the most common and most harmful quality problems of hot-rolled CGO steel.

[0004] This defect mainly manifests as follows: during hot rolling, an oxidized layer (mainly FeO and Fe2O3) with loose texture and easy to break is formed at the edge of the strip steel. When the hot-rolled coil with such defects enters the cold rolling process, these fragile edge scrap defects will peel off during the continuous high-pressure and high-tension deformation process, resulting in serious defects such as rolling leakage, peeling or strip breakage on the surface of the cold-rolled strip steel.

[0005] With the growth of market demand for oriented silicon steel and the upgrading of energy efficiency standards, the tolerance of users for the edge quality of silicon steel has further decreased. According to statistics, edge scrap defects can lead to various quality problems. According to statistics, the proportion of waste and substandard product coils caused by edge scrap defects before process optimization is as high as 3.7%. By implementing the process scheme, the proportion of this defect is significantly reduced to 0.3%, and the unqualified products caused by this defect can be reduced by 3.4 percentage points. Therefore, controlling the edge quality of hot-rolled steel is an important way to improve the qualified rate of oriented silicon steel and the competitiveness of products.

[0006] Application No. CN201810032339.8 discloses a method for preventing edge cracking of oriented silicon steel hot-rolled products by controlling the slab entry temperature, heating furnace temperature, heating time, and finish rolling and coiling temperature. The steps include: the surface temperature of the slab entering the heating furnace is not less than 300℃; the first heating section furnace gas temperature is 1160℃-1250℃; the second heating section and soaking section furnace gas temperature is 1270℃-1330℃, the heating time is 80-200 minutes, and the stationary time is not more than 30 minutes; the average grain size of the hot-rolled product edge is controlled to be not more than 72μm; the finish rolling temperature is 880℃-960℃; the coiling temperature is 500℃-620℃; and the tension of the seven-stand finishing rolling mill is reasonably controlled. The method aims to reduce edge cracking while ensuring sufficient inhibitor solid solution and electromagnetic performance.

[0007] Application No. CN118147426A discloses a method for eliminating edge cracking defects of oriented silicon steel after annealing by physical notching. The steps include: notching the bottom of the oriented silicon steel on both sides after annealing in the annealing furnace along the length direction to form notched lines, and the distance between the notched lines and the corresponding side edge is 9-11mm. This method forms shear bands and dislocations through notching, hinders abnormal grain growth at the notched position during high-temperature annealing, realizes fine-grain strengthening, and thus reduces the occurrence probability of grain edge cracking.

[0008] Application No. CN202410176905.8 discloses a copper-containing oriented silicon steel and a preparation method thereof. The bottom layer quality and surface quality of the copper-containing oriented silicon steel are improved by specific component design (such as C: 0.03%-0.06%, Si: 2.85%-3.45%, Cu: 0.4%-0.6%, etc.) and preparation process control (including heating temperature of 1250-1320℃ for hot rolling treatment, first cold rolling of the hot-rolled strip, decarburization annealing treatment control of oxygen content of 550-750ppm, and oxidation layer thickness of 7-9μm, etc.), which indirectly helps to reduce edge defects. SUMMARY

[0009] To solve the problem of a large number of edge "crumb" defects (also known as "cookie layer" defects) in copper-containing oriented silicon steel hot-rolled products, which leads to strip breakage during cold rolling, the present application aims to provide a process method for reducing edge crumb defects of copper-containing oriented silicon steel, by systematically optimizing the product component system, the entire process from slab heating to hot rolling, and thus reducing the scrap rate caused by the defects from 3.7% before improvement to a controllable range of 0.3% or less.

[0010] To solve the above technical problems, the present application adopts the following technical solutions:

[0011] The application discloses a process for reducing edge scrap defects of copper-containing oriented silicon steel.

[0012] The hot-rolled raw material has the following chemical components in percentage: C: 0.025-0.045%, Si: 3.00-3.60%, Mn: 0.16-0.24%, Als: 0.012-0.024%, Cu: 0.40-0.55%, P: 0.020% or less, S: 0.020% or less, N: 0.0070-0.0120%, and the rest is Fe and inevitable impurities;

[0013] The continuous casting blank of the oriented silicon steel is hot-charged and hot-delivered, and the hot-charging temperature is controlled to be greater than 400 DEG C.

[0014] The furnace-out temperature of the heating furnace is less than 1310 DEG C.

[0015] The time of the second heating section and the soaking section in the furnace is controlled to be less than 150 min, and the total time in the furnace is controlled to be less than 320 min.

[0016] The final rolling temperature of the finishing mill is 930-980 DEG C.

[0017] The coiling temperature is 530-590 DEG C.

[0018] Further, the hot-rolled raw material has the following chemical components in percentage: C: 0.032%, Si: 3.30%, Mn: 0.20%, Als: 0.013%, Cu: 0.48%, P: 0.017%, S: 0.009%, N: 0.0090%, and the rest is Fe and inevitable impurities.

[0019] Further, the hot-rolled raw material has the following chemical components in percentage: C: 0.035%, Si: 3.25%, Mn: 0.21%, Als: 0.012%, Cu: 0.51%, P: 0.013%, S: 0.011%, N: 0.0085%, and the rest is Fe and inevitable impurities.

[0020] Further, the hot-rolled raw material has the following chemical components in percentage: C: 0.037%, Si: 3.18%, Mn: 0.20%, Als: 0.013%, Cu: 0.52%, P: 0.015%, S: 0.006%, N: 0.0100%, and the rest is Fe and inevitable impurities.

[0021] Further, the hot-charging temperature is controlled to be 410-450 DEG C.

[0022] Further, the furnace-out temperature of the heating furnace is 1290-1300 DEG C.

[0023] Further, the final rolling temperature of the finishing mill is 948-52 DEG C.

[0024] Compared with the prior art, the present application has the beneficial technical effects:

[0025] The production process of oriented silicon steel includes hot rolling, normalizing, cold rolling, annealing and the like, and the product thickness is mainly concentrated in 0.18mm-0.27mm. Since the Si content of the oriented silicon steel is high, Si has a strong solid solution strengthening effect on a-Fe, so that the hardness and strength of the oriented silicon steel increase, and the plasticity and toughness decrease. The cold rolling production is difficult, and the strip is easily broken or cut due to defects such as edge breakage during cold rolling. In order to solve this problem, a series of innovative process optimization schemes are proposed for the steelmaking and hot rolling links, including composition optimization, hot rolling temperature control and the like, which have significant technical feasibility and economic benefits. The scheme has high promotion feasibility. It is completely based on the existing production line for process innovation, does not need to add large-scale equipment, has low investment cost, is easy to quickly embed in the existing process and realize industrialization. Through the linkage of composition and process, the edge quality of the hot rolled plate can be significantly improved, high-quality raw materials are provided for subsequent cold rolling, the risk of cold rolling breakage and edge cutting loss is greatly reduced, the yield is effectively improved, and after the scheme is implemented, the edge defect of more than 10mm is reduced from 3.7% to about 0.3%, and after promotion, the added value of the oriented silicon steel hot rolled raw material product can be further improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] The present application will be further described below in conjunction with the drawings.

[0027] Figure 1 The photo of the edge defect of the oriented silicon steel before implementation;

[0028] Figure 2 The photo of the edge quality of the oriented silicon steel after implementation of the improvement measures. DETAILED DESCRIPTION

[0029] In order to better explain the present application, the following is the specific implementation process of the present application. Tables 1-2 are the chemical composition, hot rolling process and defect statistics of Examples 1-3 and Comparative Example, respectively.

[0030] Table 1 Chemical composition (wt%) of Examples 1-3 and Comparative Example 1

[0031]

[0032] Table 2 Hot rolling process parameters and defect statistics of Examples 1-3

[0033]

[0034] By comparing Examples and Comparative Examples in Tables 1 and 2, by adjusting the Si and N contents and the ratio, simultaneously optimizing the two additions + soaking-in-furnace time and total soaking-in-furnace time, and adjusting the finishing temperature, the edge breakage defect of the copper-containing oriented silicon steel is obviously reduced.

[0035] The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application.

Claims

1. A process for reducing edge tear defects in copper-containing grain-oriented silicon steel, characterized by: Comprise: The chemical composition of the hot-rolled raw material is as follows: C: 0.025-0.045%, Si: 3.00-3.60%, Mn: 0.16-0.24%, Als: 0.012-0.024%, Cu: 0.40-0.55%, P≤0.020%, S≤0.020%, N: 0.0070-0.0120%, and the rest is Fe and inevitable impurities; The oriented silicon steel continuous casting billet is hot-charged and hot-sent, and the hot-charging temperature is controlled to be greater than 400°C; The furnace-out temperature of the heating furnace is less than 1310°C; The time of the second heating section and the soaking section in the furnace is controlled to be less than 150 min, and the total time in the furnace is less than 320 min; The final rolling temperature of the finishing mill is 930-980°C; The coiling temperature is 530-590°C.

2. The process of reducing edge crack defects in copper-containing grain-oriented silicon steel of claim 1, wherein: The chemical composition of the hot-rolled raw material is as follows: C: 0.032%, Si: 3.30%, Mn: 0.20%, Als: 0.013%, Cu: 0.48%, P: 0.017%, S: 0.009%, N: 0.0090%, and the rest is Fe and inevitable impurities.

3. The process of reducing edge crack defects in copper bearing grain oriented silicon steel of claim 1 wherein: The chemical composition of the hot-rolled raw material is as follows: C: 0.035%, Si: 3.25%, Mn: 0.21%, Als: 0.012%, Cu: 0.51%, P: 0.013%, S: 0.011%, N: 0.0085%, and the rest is Fe and inevitable impurities.

4. The process of reducing edge crack defects in copper bearing grain oriented silicon steel of claim 1 wherein: The chemical composition of the hot-rolled raw material is as follows: C: 0.037%, Si: 3.18%, Mn: 0.20%, Als: 0.013%, Cu: 0.52%, P: 0.015%, S: 0.006%, N: 0.0100%, and the rest is Fe and inevitable impurities.

5. The process of reducing edge crack defects in copper-containing grain-oriented silicon steel of claim 1, wherein: The hot-charging temperature is controlled to be 410-450°C.

6. The process of reducing edge crack defects in copper-containing grain-oriented silicon steel of claim 1, wherein: The furnace-out temperature of the heating furnace is 1290-1300°C.

7. The process of reducing edge crack defects in copper-containing grain-oriented silicon steel of claim 1, wherein: The final rolling temperature of the finishing mill is 948-52°C.

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