Flexible process rolling method capable of reducing cost and reducing working procedures and used for coiled bar production

Abstract

The invention discloses a flexible process rolling method capable of reducing cost and reducing working procedures and used for coil snail production. The flexible process rolling method comprises the following steps that A, chemical components are internally controlled during smelting of an electric arc furnace; b, the heating schedule and the rolling starting temperature are controlled, continuous casting square billet heating is adopted in the heating schedule, and the rolling starting temperature is controlled to be 1000-930 DEG C; c, the temperature in the rolling process is controlled; d, the finish rolling temperature is controlled to be 900 DEG C + / -20 DEG C; e, the cooling rate, the rapid cooling initial temperature and the rapid cooling final temperature of the rolled steel are subjected to reinforced control, and the spinning temperature is controlled to be 880-920 DEG C; and F, when the coiled screws are cooled on a Stelmor conveyor, the coiled screws are firstly rapidly cooled and then slowly cooled, cooling is conducted at the cooling speed of 4 DEG C / s-7 DEG C / s, and after cooling, the coiled screws are packaged, warehoused and stacked. The problem that produced products do not reach the standard due to the fact that process control is rough in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the field of rolling technology, in particular to a flexible rolling method for coil production which can reduce costs and procedures. Background Art

[0002] Flexible process rolling technology was proposed by Academician Wang Guodong of Northeastern University in 2006, and was proposed again at the academic conference on the development of rebar industry in August 2023 (flexible manufacturing technology is a new concept model and new development trend for realizing future factories). Flexible process rolling technology has begun to be valued by steel companies in recent years, and has now been applied to production process control by a few large steel companies, achieving good results.

[0003] When the existing flexible rolling process is used for production, the internal control of chemical composition, starting rolling temperature, final rolling temperature and cooling rate is relatively rough, and the rolled products cannot meet the expected requirements in terms of tensile strength, yield strength, toughness, etc. Therefore, the existing process needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a flexible process rolling method for coil production which can reduce costs and reduce working procedures, and solve the problem that the existing process has rough process control resulting in substandard products.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A flexible process rolling method for coil production that can reduce costs and processes includes the following steps: A. internal control of chemical composition during arc furnace smelting; B. control of heating system and rolling temperature, the heating system adopts continuous casting billet heating, and the rolling temperature is controlled at 1000°C-930°C; C. temperature control during the rolling process; D. final rolling temperature is controlled at 900°C±20°C; E. enhanced control of the cooling rate of the rolled steel, the initial temperature of rapid cooling after rolling, and the final temperature of rapid cooling, and the wire laying temperature is controlled at 880°C-920°C; F. when the coil is cooled on a Stelmor conveyor, it is first cooled quickly and then slowly, and is cooled at a cooling rate of 4°C / s-7°C / s, and is packaged, stored, stacked and stacked after cooling.

[0006] In the present application, by controlling the internal composition, the start rolling temperature, the temperature during the rolling process, the final rolling temperature and the wire laying temperature, the grain size is controlled after large deformation and rapid cooling during the rolling process, the grain size and organization precipitation in the steel are controlled, and various mechanical properties are stabilized, thereby achieving flexible control of the material organization properties, and the rolling chemical composition, mechanical properties and metallographic structure can all meet higher standard requirements.

[0007] By adjusting the heating temperature to control the austenite grain size, the austenite grains can be refined. By controlling the rolling and cooling, the dynamic recrystallization process is completed to achieve the fine grain strengthening effect and improve the yield strength. By controlling the air volume of the Stelmore blower (Stelmore model), the amount and uniformity of tissue precipitation can be controlled to obtain high-quality products with stable mechanical properties. By selecting the reasonable stacking of coil products, the temperature below the solidus line can be controlled and the long-term heat preservation can be achieved, the rolling residual stress can be reduced or eliminated, and the residual atmosphere in a small part of the steel can be eliminated. The process performance and toughness are improved to achieve the purpose of stabilizing the yield strength and the strength-to-yield ratio.

[0008] As a further preferred embodiment of the present invention, the chemical composition in step A is internally controlled to have the following mass fractions of each component: C 0.16-0.25 parts; Si 0.4-0.6 parts; Mn 1-1.25 parts; P 0-0.07 parts; S 0-0.04 parts; Ceq 0.39-0.54 parts.

[0009] In view of the high residual element content (nitrogen, molybdenum, chromium, copper, nickel, etc.) after rational use of DC arc furnace smelting products, when the residual elements are high, the amount of manganese alloy added can be reduced, and carbon and silicon-manganese alloy can be added at the same time, without adding vanadium, titanium and niobium. The use of high-wire microalloys is reduced on the original basis, and composite microalloying can be achieved at the same time.

[0010] Considering the high H and N contents in the finished steel products made in DC arc furnaces, the chemical composition is reasonably proportioned, and the heating, rolling process and stacking are controlled to reduce part of the H content in the steel and fix the N content in the steel. This makes the coil have good weldability after rolling, good yield strength and strength-to-yield ratio stability, a certain degree of corrosion resistance on the surface, and no cracks in cold bending.

[0011] As a further preferred embodiment of the present invention, the temperature of the rolling process is controlled in step C. Specifically, the microalloying of the coil requires that more than half of the rolling deformation be carried out at ≤950°C.

[0012] The advantage of this is that the deformation of the coil in the non-recrystallized austenite zone is sufficient, and the austenite can undergo dynamic recrystallization through multiple passes of cumulative plastic deformation.

[0013] As a further preferred embodiment of the present invention, in addition to controlling the heating temperature and the start rolling temperature, the final rolling temperature in step D is also controlled by using the water volume between the water cooling box in front of the finishing mill and the finishing mill group.

[0014] The purpose is to control the rolling temperature of the final rolling pass to the transformation temperature from austenite to ferrite (and deformation induced phase transformation). When the final rolling temperature is high, the grains are coarse and the strength is low.

[0015] As a further preferred embodiment of the present invention, the cooling rate after rolling in step E is required to be large in the first stage, while the cooling rate in the second stage is controlled according to the yield performance.

[0016] In order to obtain the ideal microstructure, the cooling rate of the steel after rolling, the initial temperature of rapid cooling after rolling, and the final temperature of rapid cooling must be strictly controlled (to prevent coarsening of grains).

[0017] As a further preferred embodiment of the present invention, when the coils are cooled on the Stelmore conveyor in step F, the air volume is adjusted to cool the coils on the Stelmore conveyor according to the spinning temperature, so as to lower the coiling temperature, and the temperature is controlled at <220°C.

[0018] Ensure that the mechanical properties and process performance meet national standards.

[0019] As a further preferred embodiment of the present invention, the coils are stacked at a temperature of less than 200° C. for no more than 4 hours, and the residual stress of deformation is eliminated after slow cooling.

[0020] Ensure that deformation residual stress is eliminated through slow cooling.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. In this application, by controlling the internal composition, the start rolling temperature, the temperature during the rolling process, the final rolling temperature and the wire laying temperature, the grain size is controlled after large deformation and rapid cooling during the rolling process, the grain size and organization precipitation in the steel are controlled, and various mechanical properties are stabilized, thereby realizing flexible control of the material organization properties, and the rolling chemical composition, mechanical properties and metallographic structure can all meet higher standard requirements.

[0022] 2. In view of the high residual element content (nitrogen, molybdenum, chromium, copper, nickel, etc.) after rational use of DC arc furnace smelting products, when the residual elements are high, the amount of manganese alloy added can be reduced, and carbon and silicon-manganese alloy can be added at the same time, without adding vanadium, titanium and niobium. The use of a high-line microalloy is reduced on the original basis, and composite microalloying can be achieved at the same time.

[0023] 3. Ensure that the mechanical properties and process performance meet national standards.

[0024] 4. Ensure that the residual stress of deformation is eliminated through slow cooling. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0029] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Specific embodiment 1: A flexible process rolling method for coil production that can reduce costs and processes includes the following steps: A. internal control of chemical composition during arc furnace smelting; B. control of heating system and rolling temperature, the heating system adopts continuous casting billet heating, and the rolling temperature is controlled at 1000°C; C. temperature control during the rolling process; D. final rolling temperature is controlled at 900°C; E. enhanced control of the cooling rate of the steel after rolling, the initial temperature of rapid cooling after rolling, and the final temperature of rapid cooling, and the wire laying temperature is controlled at 920°C; F. when the coil is cooled on a Stelmor conveyor, it is first cooled quickly and then slowly, and is cooled at a cooling rate of 7°C / s, and is packaged, stored, stacked and stacked after cooling; The chemical composition in step A is controlled by the following mass fractions of each component: C 0.25 parts; Si 0.4 parts; Mn 1 parts; P 0.05 parts; S 0.04 parts; Ceq 0.39 parts; The temperature control of the rolling process in step C is specifically manifested in that the microalloying of the coil requires that more than half of the rolling deformation be carried out at 950°C; In step D, the final rolling temperature is controlled by controlling the heating temperature and the start rolling temperature, and also by using the water volume between the water cooling box in front of the finishing mill and the finishing mill group; The cooling rate after rolling in step E is required to be large in the first stage, while the second stage is controlled according to the yield performance; In the step F, when the coils are cooled on the Stelmore conveyor, the air volume of the coils on the Stelmore conveyor is adjusted according to the spinning temperature to achieve the purpose of lowering the coiling temperature, and the temperature is controlled at 200° C.; The coils are stacked at 50° C. for no more than 4 hours, and the residual stress of deformation is eliminated after slow cooling. Specific embodiment 2: A flexible process rolling method for coil production that can reduce costs and processes includes the following steps: A. internal control of chemical composition during arc furnace smelting; B. control of heating system and rolling temperature, the heating system adopts continuous casting billet heating, and the rolling temperature is controlled at 930°C; C. temperature control during the rolling process; D. final rolling temperature is controlled at 920°C; E. enhanced control of the cooling rate of the steel after rolling, the initial temperature of rapid cooling after rolling, and the final temperature of rapid cooling, and the wire laying temperature is controlled at 880°C; F. when the coil is cooled on a Stelmor conveyor, it is first cooled quickly and then slowly, and is cooled at a cooling rate of 4°C / s, and is packaged, stored, stacked and stacked after cooling; The chemical composition in step A is controlled by the following mass fractions of each component: C 0.2 parts; Si 0.6 parts; Mn 1.1 parts; P 0 parts; S 0.02 parts; Ceq 0.54 parts; The temperature control of the rolling process in step C is specifically manifested in that the microalloying of the coil requires that more than half of the rolling deformation be carried out at 940°C; In step D, the final rolling temperature is controlled by controlling the heating temperature and the start rolling temperature, and also by using the water volume between the water cooling box in front of the finishing mill and the finishing mill group; The cooling rate after rolling in step E is required to be large in the first stage, while the second stage is controlled according to the yield performance; In the step F, when the coil snails are cooled on the Stelmore conveyor, the air volume of the coil snails on the Stelmore conveyor is adjusted according to the spinning temperature to achieve the purpose of lowering the coiling temperature, and the temperature is controlled at <150°C; The coils are stacked at 150° C. for no more than 4 hours, and the residual stress of deformation is eliminated after slow cooling. Specific embodiment 3: A flexible process rolling method for coil production that can reduce costs and processes includes the following steps: A. internal control of chemical composition during arc furnace smelting; B. control of heating system and rolling temperature, the heating system adopts continuous casting billet heating, and the rolling temperature is controlled at 950°C; C. temperature during rolling process is controlled; D. final rolling temperature is controlled at 880°C; E. cooling rate of steel after rolling, initial temperature of rapid cooling after rolling and final temperature of rapid cooling are strengthened, and the wire laying temperature is controlled at 900°C; F. when the coil is cooled on a Stelmor conveyor, it is first cooled quickly and then slowly, and is cooled at a cooling rate of 5°C / s, and is packaged, stored, stacked and stacked after cooling; The chemical composition in step A is controlled by the following mass fractions of each component: C 0.16 parts; Si 0.5 parts; Mn 1.25 parts; P 0.07 parts; S 0 parts; Ceq 0.45 parts; The temperature control of the rolling process in step C is specifically manifested in that the microalloying of the coil requires that more than half of the rolling deformation be carried out at 950°C; In step D, the final rolling temperature is controlled by controlling the heating temperature and the start rolling temperature, and also by using the water volume between the water cooling box in front of the finishing mill and the finishing mill group; The cooling rate after rolling in step E is required to be large in the first stage, while the second stage is controlled according to the yield performance; In the step F, when the coil snails are cooled on the Stelmore conveyor, the air volume of the coil snails on the Stelmore conveyor is adjusted according to the spinning temperature to achieve the purpose of lowering the coiling temperature, and the temperature is controlled at 190° C.; The coils are stacked at a temperature of less than 190° C. for no more than 4 hours, and the residual stress of deformation is eliminated after slow cooling.

[0033] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flexible process rolling method for coil production that can reduce costs and processes, characterized in that: The method comprises the following steps: A. internal control of chemical composition during smelting in an electric arc furnace; B. control of the heating system and the rolling temperature, wherein the heating system adopts continuous casting billet heating, and the rolling temperature is controlled at 1000°C-930°C; C. temperature control during the rolling process; D. final rolling temperature is controlled at 900°C±20°C; E. strengthening control over the cooling rate of the steel after rolling, the initial temperature of rapid cooling after rolling, and the final temperature of rapid cooling, and the wire laying temperature is controlled at 880°C-920°C; F. when the coil is cooled on the Stelmor conveyor, it is first cooled quickly and then slowly, and is cooled at a cooling rate of 4°C / s-7°C / s, and is packaged and stored for stacking after cooling.

2. The flexible process rolling method for coil production capable of reducing costs and processes according to claim 1, characterized in that: The chemical composition in step A is internally controlled to have the following mass fractions of each component: C 0.16-0.25 parts; Si 0.4-0.6 parts; Mn 1-1.25 parts; P 0-0.07 parts; S 0-0.04 parts; Ceq 0.39-0.54 parts.

3. The flexible process rolling method for coil production capable of reducing costs and processes according to claim 1, characterized in that: The temperature control during the rolling process in step C is specifically manifested in that the microalloying of coil requires that more than half of the rolling deformation be carried out at ≤950°C.

4. The flexible process rolling method for coil production capable of reducing costs and processes according to claim 1, characterized in that: In step D, the final rolling temperature is controlled by controlling the heating temperature and the start rolling temperature, and also by using the water volume in the water cooling box in front of the finishing mill and between the finishing mill groups.

5. The flexible process rolling method for coil production capable of reducing costs and processes according to claim 1, characterized in that: The cooling rate after rolling in step E is required to be large in the first stage, while the second stage is controlled according to the yield performance.

6. The flexible process rolling method for coil production capable of reducing costs and processes according to claim 1, characterized in that: When the coil snails are cooled on the Stelmore conveyor in step F, the air volume of the coil snails on the Stelmore conveyor is adjusted according to the spinning temperature to achieve the purpose of lowering the coiling temperature, and the temperature is controlled at <220°C.

7. The flexible process rolling method for coil production capable of reducing costs and processes according to claim 1, characterized in that: The coils are stacked at a temperature of less than 200° C. for no more than 4 hours, and the residual stress of deformation is eliminated after slow cooling.