Special cooling method for ferritic stainless steel

A cooling method, stainless steel technology, applied in metal processing equipment, metal rolling, manufacturing tools, etc., can solve problems such as waste, affecting the surface quality of the head and tail of the strip, and the surface quality of watermarks

Active Publication Date: 2012-07-18
SHANXI TAIGANG STAINLESS STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this state, the surface temperature of the hot-rolled strip before coiling is generally above 700°C, and at this temperature, the surface hardness of ferritic stainless steel is softer than that of any other steel. The equipment such as the pinch roll and the auxiliary roll are all cold cast iron products with high surface hardness. In order to achieve smooth coiling and good coil shape during the coiling process, the linear speed of the pinch roll and the auxiliary roll is the same as that of the strip. There are certain differences, which lead to misalignment between the surface of the strip steel and the surface of the roll, causing scratches on the surface of the strip steel. Such scratches seriously affect the surface quality of the head and tail of the strip steel, and generally make the ferritic steel Scratch scratches of different lengths on the head and tail of different kinds of steel strips, which cannot be used and cause large waste
However, if the cooling length is too long or the cooling temperature is too low, it is easy to cause surface quality problems such as watermarks

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0095] Embodiment 1: Cooling method for SUS430 steel grade

[0096] The hardness coefficient alpha_nn of this steel type is 0.88, then according to the head-to-tail cooling length formula:

[0097] Head cooling length L h = 10 / alpha_nn = 10 / 0.88=11.4 (meters)

[0098] Tail cooling length L t = 15 / alpha_nn =15 / 0.88=17.05 (meters)

[0099] The target temperature for head coiling is 630°C, and the target temperature for tail coiling is 635°C.

[0100] According to the target temperature, the computer laminar cooling program automatically sets the opening and closing conditions of the valves at the head and tail. For example, when the finishing rolling exit temperature is 880°C, the opening and closing settings of each valve are:

[0101] Head: Set 1# valve, 2# valve, 3# valve, 4# valve to close, that is, no water spraying; 5#~12# valve opening is 100, and other openings are 0. Tail: Set 1# valve, 2# valve, 3# valve, 4# valve to close, that is, no water spraying; 5#~10# valve...

Embodiment 2

[0102] Embodiment two: cooling method for 409L steel type

[0103] The hardness coefficient alpha_nn of this steel grade is 0.76, then according to the head-to-tail cooling length formula:

[0104] Head cooling length L h = 10 / alpha_nn = 10 / 0.76=13.16 (meters)

[0105] Tail cooling length L t = 15 / alpha_nn =15 / 0.76=19.74 (meters)

[0106] The target temperature for head coiling is 620°C, and the target temperature for tail coiling is 630°C.

[0107] According to the target temperature, the computer laminar flow cooling program automatically sets the opening and closing conditions of the valves at the head and tail. For example, when the finish rolling outlet temperature is 840°C, the opening and closing settings of each valve are:

[0108] Head: Set 1# valve, 2# valve, 3# valve, 4# valve to close, that is, no water spray; 5#~11# valve opening is 100, and the rest are 0. Tail: Set 1# valve, 2# valve, 3# valve, 4# valve to close, that is, no water spraying; 5#~8# valve open...

Embodiment 3

[0109] Embodiment three: the cooling method aimed at the coinage steel CTSZB steel grade

[0110] The hardness coefficient alpha_nn of this steel grade is 0.86, then according to the head-to-tail cooling length formula:

[0111] Head cooling length L h = 10 / alpha_nn = 10 / 0.86=13.16 (meters)

[0112] Tail cooling length L t = 15 / alpha_nn =15 / 0.86=19.74 (meters)

[0113] The target temperature for head coiling is 620°C, and the target temperature for tail coiling is 630°C.

[0114] According to the target temperature, the computer laminar flow cooling program automatically sets the opening and closing conditions of the valves at the head and tail. For example, when the finish rolling outlet temperature is 840°C, the opening and closing settings of each valve are:

[0115] Head: Set 1# valve, 2# valve, 3# valve, 4# valve to close, that is, no water spray; 5#~11# valve opening is 100, and the rest are 0. Tail: Set 1# valve, 2# valve, 3# valve, 4# valve to close, that is, no w...

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PUM

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Abstract

A special cooling method for ferritic stainless steel includes cooling and coiling of the head of the ferritic stainless steel, and cooling and coiling of the tail of the ferritic stainless steel. The method is characterized in that a cooling device comprises 48 set of laminar cooling valves, namely from the 1# valve set to the 48# valve set, each set of valves includes an upper valve and a lower valve, the upper valve and the lower valve of 1-4# valve sets do not spray water, starting from the 5# valve set, water is sprayed from the front to the back, a type of the valves for dense water spraying type is chosen, opening and closing of the valves are automatically controlled by a computer, and the temperature of a coiled target is dynamically controlled by the aid of the automatic opening and closing of the valves. The cooling and coiling of the head includes the head cooling length and the head cooling temperature, and the cooling and coiling of the tail includes the tail cooling length and the tail cooling temperature, wherein the head cooling length is: Lh=10/alpha_nn (meter) and the tail cooling length is: Lt=15/alpha_nn (meter). The special cooling method for the ferritic stainless steel reduces the scratches on the surface of ferritic stainless strip steel.

Description

technical field [0001] Through process research and control model development, this technology has added the laminar flow cooling function of ferritic stainless steel in the hot continuous rolling production plant. Scratch and scratch defects on the surface of the strip steel head and tail, improve the quality of hot-rolled products and the yield of hot-rolled products, so this technology belongs to metallurgical process control and automation technology in the category of metallurgical science and technology. Background technique: [0002] Due to the low surface hardness of ferritic stainless steel, the speed of the pinch roll and the helper roll is ahead of the strip steel during the coiling process of hot continuous rolling, so the relative sliding between the strip steel and the roll surface will cause the surface of the strip steel to be scratched. When this phenomenon is serious It can make the head and tail of each strip steel more than ten meters become waste product...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21B45/02
Inventor 邱华东郭永亮
Owner SHANXI TAIGANG STAINLESS STEEL CO LTD
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