CN114085970A

CN114085970A - Manufacturing method for overcoming hot-rolled soft and hard edges of ferritic stainless steel

Info

Publication number: CN114085970A
Application number: CN202111355959.3A
Authority: CN
Inventors: 梁健浑; 徐向东; 方剑锋; 黄卫文; 谢水旺; 罗杰; 林杰
Original assignee: Angang Lianzhong Guangzhou Stainless Steel Co ltd
Current assignee: Angang Lianzhong Guangzhou Stainless Steel Co ltd
Priority date: 2021-11-16
Filing date: 2021-11-16
Publication date: 2022-02-25
Anticipated expiration: 2041-11-16
Also published as: CN114085970B

Abstract

A manufacturing method for overcoming ferrite stainless steel hot-rolled soft and hard edges is characterized in that a heat preservation pit slow cooling mode is adopted for a hot-rolled steel coil, and meanwhile heat provided by other hot coils is utilized, so that the temperature in the area where the hot-rolled steel coil is located is slowly reduced, and the steel coil can be uniformly heated and slowly cooled. The invention adopts special slow cooling measures, utilizes the heat preservation function of the heat preservation pit and other hot coils to provide heat, slowly reduces the temperature in a certain area, achieves the purposes of uniformly heating and slowly cooling the steel coil, is beneficial to the transformation of the gamma phase into the alpha phase in the phase change process, effectively improves the mechanical property, and solves the problem of poor forming performance of 430\ White.

Description

Manufacturing method for overcoming hot-rolled soft and hard edges of ferritic stainless steel

Technical Field

The invention belongs to the technical field of metallurgical steel rolling, and particularly relates to a manufacturing method for overcoming ferrite stainless steel hot-rolled soft and hard edges.

Background

The existing 430\ White product is placed in a storage area after hot rolling, the temperature is continuously reduced, the temperature difference between the inside and the outside is larger and larger, the cooling speed of each part is not uniform, the mechanical property is not uniform, and the problems of concave-convex stripes and poor mechanical property of downstream formed products are caused.

Disclosure of Invention

The invention aims to provide a manufacturing method for overcoming a ferrite stainless steel hot-rolled soft and hard edge, which can reduce a series of cost problems caused by poor performance through controlling the forming performance.

In order to achieve the purpose, the invention adopts the following technical scheme:

a manufacturing method for overcoming ferrite stainless steel hot-rolled soft and hard edges is characterized in that a heat preservation pit slow cooling mode is adopted for a hot-rolled steel coil, and meanwhile heat provided by other hot coils is utilized, so that the temperature in the area where the hot-rolled steel coil is located is slowly reduced, and the steel coil can be uniformly heated and slowly cooled.

The method specifically comprises the following steps:

1) and (3) heating process of the heat preservation pit: preparing a heat preservation pit in advance according to the production time, hoisting the black-skin steel coil produced by hot rolling at the temperature of between 840 and 900 ℃ into the heat preservation pit, utilizing the heat of the black-skin steel coil to increase the temperature of the heat preservation pit, arranging the black-skin steel coils in rows, and arranging intervals between the rows to increase the temperature in the heat preservation pit to 400 and 500 ℃;

2) and (3) furnace charging with temperature: after the hot rolled steel coils needing to overcome the soft and hard edges are produced, the hot rolled steel coils are immediately lifted and transported into the heat preservation pit, arranged among the black skin preheated steel coils in a row, and the heat preservation pit is closed to form a closed space;

3) and (3) heat preservation: the steel coils need to be stacked in the heat preservation pit for more than 24 hours, and the steel coils are slowly cooled;

4) and (3) cooling: and opening an upper cover of the heat preservation pit, contacting with the outside, reducing the temperature to 40 ℃ at a cooling rate of 20-60 ℃/h, and then discharging to perform the next procedure treatment.

The thickness of the hot-rolled steel coil is 2.5-10 mm, and the width is 800-1500 mm.

The coiling temperature of the hot-rolled steel coil is 800-1000 ℃.

Compared with the prior art, the invention has the beneficial effects that:

1) the invention adopts special slow cooling measures, utilizes the heat preservation function of the heat preservation pit and other hot coils to provide heat, slowly reduces the temperature in a certain area, achieves the purposes of uniformly heating and slowly cooling the steel coil, is beneficial to the transformation of the gamma phase into the alpha phase in the phase change process, effectively improves the mechanical property, and solves the problem of poor forming performance of 430\ White.

2) The coiling temperature of the slowly-cooled steel coil is set at 880 ℃, which is beneficial to acid washing of the downstream of the steel coil, and simultaneously takes into account a high enough output temperature, and the mechanical property is improved by matching with slow cooling.

3) The method can effectively solve the problem of poor forming performance of 430\ White, the HRB of the black skin slow cooling roll is 4-8% lower than that of a common roll, and the elongation of the slow cooling roll is improved by about 3-17%.

Drawings

FIG. 1 is a graph comparing the tensile strength of examples of the present invention with that of a conventional steel grade which is not particularly slowly cooled.

FIG. 2 is a graph comparing the yield strength of examples of the present invention with that of a conventional steel grade without particularly slow cooling.

FIG. 3 is a graph showing the comparison of the elongation of examples of the present invention with that of a conventional steel grade which is not particularly gradually cooled.

FIG. 4 is a graph comparing hardness strength of examples of the present invention with that of general steel grades not particularly slow-cooled.

Detailed Description

The following embodiments are further illustrated by reference to the following specific examples:

in the embodiment of the invention, the black-skin steel coil without soft and hard edge requirements and the hot-rolled steel coil with soft and hard edge requirements are sequentially produced, and the black-skin steel coil needs to be advanced for 3-4 hours.

The compositions of the steel grades of the examples are shown in Table 1; the hot rolling process parameters of the examples are shown in Table 2; the arrangement positions of the heat preservation pits of the black strip steel coil and the hot-rolled slow-cooling steel coil in the embodiment are shown in the table 3.

Table 1 examples steel grade composition (wt%)

C	Si	Mn	P	S	Ni	Cr	Mo	Cu	N
										0.04	0.35	0.334	0.026	0.003	0.141	16.15	0.008	0.045	0.045

TABLE 2 examples Hot Rolling Process parameters

TABLE 3 arrangement position of the insulation pit

1) And (3) heating process of the heat preservation pit: preparing a heat preservation pit in advance according to production time, immediately hoisting and conveying the common black skin steel coils into the heat preservation pit after the common black skin steel coils are produced, arranging the black skin steel coils in rows, and arranging intervals between the rows so as to enable the temperature in the heat preservation pit to rise to 400-500 ℃;

according to the rate (4-6 minutes/coil) of the black strip steel coil produced by hot rolling, along with more and more preheated black strip steel coils in the heat preservation pit, the temperature in the heat preservation pit can be higher and higher, and when the preheated coil is fully placed, the time is required to be consumed for 3-4 hours, and the temperature in the pit can reach 400-500 ℃.

2) And (3) furnace charging with temperature: after the hot rolled steel coils needing to overcome the soft and hard edges are produced, the hot rolled steel coils are immediately hoisted into the heat preservation pits and are arranged among the black skin preheated steel coils in rows, and meanwhile, the heat preservation pits are closed to form a closed space;

4) and (3) cooling: and opening the upper cover of the heat preservation pit, reducing the temperature to 40 ℃ at the rate of 20-60 ℃/h, and then discharging the product for the next procedure.

In the hot rolling process, the temperature of the steel coil is effectively controlled to uniformly and slowly decrease through the heat preservation pit, so that the black skin annealing process effect is achieved, and the effect is shown in the figures 1-4 compared with the effect in the prior art.

Claims

1. A manufacturing method for overcoming ferrite stainless steel hot-rolled soft and hard edges is characterized in that a heat preservation pit slow cooling mode is adopted for a hot-rolled steel coil, and meanwhile heat provided by other hot coils is utilized, so that the temperature in the area where the hot-rolled steel coil is located is slowly reduced, and the steel coil can be uniformly heated and slowly cooled.

2. The manufacturing method for overcoming the hot-rolled soft and hard edge of the ferritic stainless steel according to claim 1 is characterized by comprising the following steps:

1) and (3) heating process of the heat preservation pit: hoisting the black-skin steel coil produced by hot rolling at the temperature of 840-900 ℃ to a heat-preservation pit, and increasing the temperature of the heat-preservation pit by using the heat of the black-skin steel coil, wherein the black-skin steel coils are arranged in rows, and intervals are arranged between the rows so as to increase the temperature in the heat-preservation pit to 400-500 ℃;

3) and (3) heat preservation: the steel coil is stacked in the heat preservation pit for more than 24 hours, and the steel coil is slowly cooled;

3. The method as claimed in claim 2, wherein the thickness of the hot rolled steel coil is 2.5-10 mm, and the width thereof is 800-1500 mm.

4. The manufacturing method for overcoming the hot rolled soft and hard edge of ferritic stainless steel as set forth in claim 2, characterized in that the coiling temperature of the hot rolled steel coil is 800-1000 ℃.