CN101653779A - Effective hot rolled steel strip production process EHSP and method thereof - Google Patents

Abstract

The invention belongs to the field of forming technology, in particular relates to an effective hot rolled steel strip process EHSP and a method thereof. A first-class conventional continuous casting(200-230mm) plate blank and a second-class thin plate blank of a thickness of 70/55mm are combined to form a production process route of a set of continuous-casting and tandem-rolling production line.The hot rolled steel strip process is characterized by the thin slab continuous-casting and tandem-rolling production process characteristics as well as wide range, high surface quality and good postmachining properties of conventional hot tandem-rolling products, and has a whole-line production capacity up to 3.5 millions t/a. The effective hot rolled steel strip process is smooth and compact in process flows, simple and reasonable in the equipment configuration, high in the production efficiency, good in the product quality and high in the added value of the products, and can be applied tothe construction of a newly made or improved continuous-casting and tandem-rolling hot rolled steel strip mills.

Description

A kind of hot-rolled steel strip production technology-EHSP and method

technical field

The invention belongs to the technical field of forming, and relates to a process for producing hot-rolled wide strip steel by continuous casting and rolling, in particular to a production process for hot-rolled strip steel—EHSP (Effective Hot Strip Process) and the method.

Background technique

Since the advent of thin slab continuous casting and rolling technology, after years of development, there are mainly technologies such as CSP of German SMS company, FTSR of Italian Danieli company, DSP combined with casting machine of Italian Danieli company and Japanese Mitsubishi rolling mill, and Japanese Sumitomo Metal Company QSP. , the main problem of the pure thin slab continuous casting and rolling process is that the thickness of the cast slab is too thin, which causes the surface quality of the product to be low and the yield strength ratio is high, so it is difficult to supply high-grade cold-rolled raw materials. The capacity is about 2.4 million tons, and the efficiency of the rolling line has not been fully utilized.

There are two obvious deficiencies in the continuous casting and rolling production line that has been used at present: one is that only two-strand continuous casting can be used, the maximum output is about 2.4 million tons, and the production capacity of the rolling line cannot be fully utilized; the other is that the products produced are due to The defects of the process itself, the variety produced is single, and it is difficult to provide cold-rolled raw materials. So far, all thin slab continuous casting and rolling production lines in the world have rolled first-class or two-strand thin slabs, and there is no precedent for combined production of thick and thin slabs.

Contents of the invention

The purpose of the present invention is to propose a hot-rolled steel strip production process-EHSP and method. Using 1 strand of conventional continuous casting (200-230mm) slab, 2 strands of 70/55mm thick thin slab, combined into a production process route of a continuous casting and rolling production line. The invention not only has the production process characteristics of thin slab continuous casting and rolling, but also has the characteristics of wide range of conventional hot rolling products, high surface quality and good subsequent processing performance of products, and the production capacity of the whole line can be as high as 3.5 million t/a.

It adopts 1-strand conventional continuous casting (200-230mm) slab, and the walking beam heating furnace realizes the heating and buffering of the slab. The 70mm intermediate strip billet enters the horizontally movable roller hearth furnace, and then enters the 7-stand continuous rolling unit according to the rolling section to be rolled into a finished steel coil; two strands of 70/55mm thick thin slab are used, and the The roller hearth heating furnace realizes the heating and buffering of the slab, enters into the horizontally movable roller hearth furnace, and then enters the 7-stand continuous rolling unit according to the rolling schedule to be rolled into finished steel coils.

This method uses two streams of 70mm and 55mm thick continuous casting slabs, which are cut into slabs with a maximum length of 42m by swing shearing. ℃, and then enter the continuous rolling production line in parallel with a horizontally movable roller hearth furnace. After descaling by high-pressure water, it is rolled into an intermediate billet of 25mm-40mm by two irreversible tandem roughing mills. After cutting the head and tail, high-pressure water After descaling, it is rolled into 1.0-12.7mm thick hot-rolled steel strip by 5 finishing mills, cooled by laminar flow cooling device, and coiled by coiler; the third flow continuous casting machine produces 210mm thick conventional continuous casting slab, The slab is sent to the walking heating furnace through the conventional continuous casting machine's exit roller table and furnace entry roller table. The slab is heated to 1100°C-1250°C and then released from the furnace. A 70mm thick intermediate billet is made, and then enters the horizontally movable roller hearth furnace and then flows into the aforementioned same 7-stand continuous rolling production line to be rolled into a hot-rolled steel coil.

Since the method adopts a continuous casting machine with a combination of thick and thin, and realizes three-strand parallel rolling, the production capacity of continuous casting and rolling is significantly improved. The annual production capacity of the entire production line can reach 3.5 million to 4 million tons, fully The high-efficiency production capacity of the rolling line has been brought into play; at the same time, the third stream uses conventional continuous casting (200-230mm) slabs to improve the surface quality of the casting slabs, and can produce products with higher quality requirements than the existing thin slab continuous casting and rolling processes. Higher products and high-grade cold-rolled raw steel coils have wide product coverage, high added value, and good surface quality; the other two streams are typical thin slab continuous casting and rolling, which can give full play to short-process, near-net-shape rolling Advantages of the manufacturing process to produce fine-grained, high-strength, ultra-thin strip steel, and can also take advantage of the special as-cast structure of the thin slab continuous casting and rolling cast slab, the uniform temperature of the rolled piece, and the advantages of good deformation conditions Constant temperature, constant speed rolling additional For silicon steel products with high value, the recrystallization of the final hot-rolled silicon steel coil is very sufficient, and the magnetic induction value is significantly improved.

At present, the major tasks of my country's national economic restructuring are independent innovation, energy saving, consumption reduction and emission reduction, and building a resource-saving society. The continuous casting and rolling process can greatly reduce fuel consumption, metal consumption and flue gas emissions, which is in line with the general development direction of the country on energy saving, consumption reduction and emission reduction. Therefore, a new type of continuous casting and rolling production process has been innovated Applied to the production of hot-rolled wide-band steel, it can not only overcome the shortcomings of low output of thin slab continuous casting and rolling, poor surface, and weak subsequent processing performance of products, but also give full play to the energy saving and emission reduction of thin slab continuous casting and rolling. It is of great significance to the development of my country's iron and steel industry to inject new and powerful vitality into the existing or proposed thin slab continuous casting and rolling of the traditional advantages of crystal high-strength thin-gauge products and silicon steel production. The present invention adds a first-class thick-slab rough-rolling line to a two-strand thin-slab continuous casting and rolling production line, and simultaneously realizes the parallel rolling technology of three-strand slabs, which is the first in the world.

The content included in the present invention is:

Adopt 1-strand conventional continuous casting (200-230mm) slab, realize the heating and buffering of the slab by walking beam heating furnace, and use the strong four-roller reversible roughing mill with vertical rollers to reciprocate after descaling by high-pressure water The 70mm intermediate strip billet is made, enters the roller hearth furnace that can move horizontally, and then enters the 7-stand continuous rolling unit according to the rolling schedule to be rolled into finished steel coils;

The 2-strand 70/55mm thick thin slab is used, the slab is heated and buffered by the roller hearth heating furnace, enters the horizontally movable roller hearth furnace, and then enters the 7-stand continuous rolling unit according to the rolling schedule. rolled into finished coils;

The invention realizes parallel rolling of 3-strand slabs formed by combining thick and thin continuous casting slabs, and also realizes the rational division of labor for the production of products of different varieties, specifications and uses using different continuous casting slabs, greatly improving the efficiency of continuous casting and continuous casting. The production capacity of the rolling production line also gave full play to the rolling capacity of the tandem rolling unit. It not only has the production process characteristics of thin slab continuous casting and rolling, but also has the characteristics of wide range of conventional hot rolling products, high surface quality and good subsequent processing performance of products.

The invention has smooth and compact technological process, simple and reasonable equipment composition, high production efficiency, good product quality and high added value.

Description of drawings

The attached picture is a schematic diagram of the EHSP process and equipment configuration

In the figure: Part 1 is a continuous casting machine, Part 2 is a swing shear, Part 3 is a high-pressure water descaling box, Part 4 is two R1 and R2 four-roll irreversible roughing mills, Part 5 is a cutting head flying shear, and Part 6 It is a rapid cooling device, item 7 is a high-pressure descaling box, item 8 is a F1-F5 finishing mill, item 9 is a laminar flow cooling device, item 10 is two downcoilers, and item 11 is a walking beam heating furnace , Part 12 is a high-pressure descaling box, and Part 13 is a four-roll reversible roughing mill.

Detailed ways

The present invention is described in detail in conjunction with accompanying drawing:

Qualified molten steel is cast by the continuous casting machine 1 into a continuous casting slab of 70-90mm and pressed down to 55-70mm by the liquid core. According to the different steel types, the slab from the continuous casting machine 1 is pulled out at different casting speeds. When the length of the cast slab reaches the set length (max. After cutting, the slab is immediately sent to the roller hearth heating furnace for heating, and the slab after reaching the set furnace temperature (1050-1180°C) enters the high-pressure water descaling box 3. Use high-pressure water to remove the generated during the heating process. The oxide scale is then sent to two R1 and R2 four-roll irreversible roughing mills 4. The slab is rolled into an intermediate strip with a thickness of about 20-40mm through two R1 (with vertical rolls) and R2 four-roll irreversible roughing mills 4 . Vertical roll rolling can precisely control the strip width and increase and improve the edge quality of the strip. The intermediate strip then enters the cutting head flying shear 5 to cut off the irregular head and tail, and then enters the rapid cooling device 6 for the strip steel that needs ferrite rolling; for the strip steel that does not undergo ferrite rolling, it passes through Rapid cooling device 6, and then the strip steel enters the high-pressure descaling box 7, removes the scale with high-pressure water, and then sends it to the F1-F5 finishing rolling unit 8 for rolling, and the thickness of the finished strip steel reaches 1.0 -12.7mm. The finished steel strip is laminarly cooled through the laminar flow cooling device 9, and after the strip steel is cooled to the target temperature, it is coiled through two downcoilers 10; the walking beam heating furnace 11 is a walking beam heating furnace, which can Conventional continuous casting (200-230mm) slabs are heated and released after reaching the set temperature, then enter the high-pressure descaling box 12 and use high-pressure water to remove the iron oxide scale generated during the heating process, and then enter a four-roller reversible roughing mill 13 Reciprocating rolling to form a 70mm thick intermediate strip billet enters the horizontal moving roller hearth furnace for soaking and heat preservation, and according to the rolling section of the 2-strand thin slab, it is merged into the 7-stand continuous rolling line for rolling in the rolling gap. The technological process after entering the high-pressure water descaling box 3 is the same as above.

The invention realizes the reasonable distribution of production capacity of thick and thin casting machines and the reasonable division of labor for the production of products of different varieties, specifications and uses using different continuous casting slabs, greatly improving the production capacity of the continuous casting and rolling production line. The thick continuous casting slab improves the surface quality of the slab, and can produce products with higher quality requirements than the existing thin slab continuous casting and rolling process, as well as high-grade raw material steel coils for cold rolling, with wide product coverage, high added value, The surface quality is good; the other two streams give full play to the advantages of thin slab continuous casting and rolling short process and near-net shape rolling process to produce fine-grained, high-strength, ultra-thin strip steel, and thin slab continuous casting and rolling can also be used to cast slabs Silicon steel products with special state structure, uniform temperature of the rolled piece, good deformation conditions, constant temperature, constant speed rolling, sufficient recrystallization, and high magnetic induction value.

The invention has smooth and compact technological process, simple and reasonable equipment composition, high production efficiency, good product quality and high added value, and can be widely used in the production of hot-rolled strip steel.

Claims (4)

1. A hot-rolled steel strip production process-EHSP, is characterized in that: adopt 1-strand conventional continuous casting (200～230mm) slab, 2 strands 70/55mm thick thin slab, be combined into a set of continuous casting and rolling production line production process route. 2. The method of hot-rolled steel strip production process-EHSP according to claim 1, characterized in that: the slab of 1-strand conventional continuous casting (200～230mm) is heated by the walking beam type heating furnace and buffering, after descaling by high-pressure water, a strong, high-speed reversible roughing mill is used to roll back and forth into a 70mm intermediate strip, which enters a roller hearth furnace that can move horizontally, and then enters the 7-stand continuous strip according to the rolling rhythm. Rolling mills roll into finished steel coils; 2 streams of 70/55mm thick thin slabs are heated and buffered by roller hearth heating furnaces, and then enter into horizontally movable roller hearth furnaces, and then merged according to the rolling schedule. The line enters the 7-stand continuous rolling mill to be rolled into finished steel coils. 3. the method for hot-rolled steel strip production technology-EHSP according to claim 1, is characterized in that: this method adopts the thin slab of 2 streams 70 and 55mm thick, is cut into the slab of longest 42m through swinging shears, The two streams of thin slabs respectively pass through two roller hearth heating furnaces to heat the slabs to a temperature of 1050°C~1180°C, and then flow into the continuous rolling production line in parallel with a horizontally movable roller hearth furnace. After descaling by high-pressure water, the two The irreversible tandem roughing mill is rolled into a 25mm-40mm intermediate billet, and then rolled into a 1.0-12.7mm thick hot-rolled strip steel with a laminar flow cooling device Cooling, coiler coiling; the third-stream continuous casting machine produces 210mm thick conventional continuous casting slabs, which are sent to the walking heating furnace through the conventional continuous casting machine billet exit roller table and furnace entry roller table, and the slab temperature is heated to After being released from the furnace at 1100℃～1250℃, after high-pressure water descaling, it enters the four-high reversible roughing mill and rolls back and forth to form a 70mm thick intermediate billet, enters the horizontally movable roller hearth furnace, and then flows into the same 7 racks mentioned above The continuous rolling line is rolled into hot-rolled steel coils. 4. The hot-rolled steel strip production process-EHSP and method according to claims 1 and 2, characterized in that: the process system of three-strand parallel rolling, the timing of incorporating the thick slab into the continuous rolling production line after rough rolling: a. 2 stream 70/55mm thick thin plate continuous casting machine stop pouring time; b.2 The filling time between the start of pouring of the 70/55mm thick thin slab continuous casting machine and the filling of the slab to the cross section of the roller hearth furnace; c.2 When the 70/55mm thick thin slab continuous casting machine is in normal production, the time difference between casting a thin slab and rolling a thin slab by using the continuous casting machine (continuous casting casting speed is low, casting time is long), and the bottom of the roll is quickly squeezed out The slab is accumulated in the furnace, and the accumulated time difference is used for the parallel rolling of the intermediate slab after the rough rolling of the thick slab, that is, to realize the cross rolling of thick and thin slabs.

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