CN111394560A

CN111394560A - Production method of hot-rolled ribbed steel bar

Info

Publication number: CN111394560A
Application number: CN202010246609.2A
Authority: CN
Inventors: 高建文; 李志敏; 杨伟; 齐亮彬; 熊蜂; 谭傲霜; 陈盼吉
Original assignee: Hunan Valin Xiangtan Iron and Steel Co Ltd
Current assignee: Hunan Valin Xiangtan Iron and Steel Co Ltd
Priority date: 2020-03-31
Filing date: 2020-03-31
Publication date: 2020-07-10

Abstract

The production method of the hot-rolled ribbed steel bar comprises the following steps that the specification of the hot-rolled wire rod of the spring steel is phi 8 mm-phi 10mm, the chemical components of the steel comprise, by mass, 0.20% -0.25% of C, 0.40% -0.50% of Si, 1.40% -1.60% of Mn, less than or equal to 0.045% of P, less than or equal to 0.045% of S, 0.015% -0.020% of V, and the balance of Fe and inevitable impurity elements; the rolling process comprises the following steps: the tapping temperature is 1070-1130 ℃, the pre-finish rolling temperature is 970-1000 ℃, and the finish rolling temperature is 840-880 ℃; the spinning temperature is 845-875 ℃; the finishing temperature is below the recrystallization temperature of an austenite region; rapidly cooling the roller bed by a fan on an air cooling roller bed, wherein the air volume is 100%; and (4) performing heat preservation by closing the roller way of the heat preservation cover, wherein the temperature of the heat preservation cover is 640-660 ℃, the temperature of the heat preservation cover is 600-620 ℃, and the time of the heat preservation cover is 45-55 s. The invention not only ensures the stable operation of the equipment, but also reduces the alloy content and reduces the cost by adding a small amount of V alloy and finish rolling and low-temperature rolling.

Description

Production method of hot-rolled ribbed steel bar

Technical Field

The invention relates to the technical field of metal material processing and forming, in particular to a production method of a hot-rolled ribbed steel bar, and particularly relates to a production method of a coiled steel bar with a height line phi of 8 mm-10 mm HRB 400E.

Background

In the current thread steel market, HRB400E is more. The microalloy strengthening method is the main international production mode of HRB400E, and the microalloy mainly comprises vanadium alloy or niobium alloy, so that a large amount of alloy resources are consumed each year. The supply of these alloying elements is short due to the limited mineral resources containing vanadium and niobium. Therefore, if the alloy content of the HRB400E steel bar can be reduced, great economic and social benefits can be generated.

In the prior art, a double-line rolling production line without a reducing diameter rolling mill generally adopts vanadium alloy to strengthen to produce HRB400E, and the mass percentage content of vanadium is 0.035-0.045%.

Chinese patent CN104357741A discloses an HRB400E high-strength anti-seismic steel bar spiral shell and a production method thereof, and the method comprises a reducing and sizing rolling mill to obtain a finished product, so that a finish rolled steel piece can be rolled at a low temperature of 730-760 ℃ to obtain finer grains, and the method is not suitable for production line production without the reducing and sizing rolling mill. Chinese patent CN 110184516A discloses a preparation method of a spiral shell with high line diameter of 6 mm-HRB 400E, which starts low-temperature rolling from a heating temperature by means of strong rolling capacity of equipment to realize the production without adding micro alloy, and the method has the defects of high requirements on the strength of rough and medium rolling equipment and the performance of a motor, particularly for a twisted rolling production line, the experimental life of the equipment is shortened, the maintenance cost of the equipment is increased, and the yield strength of the spiral shell with high line diameter of 6 mm-HRB 400E produced by the method is insufficient, so that the performance qualification rate is difficult to ensure.

Disclosure of Invention

The invention aims to provide a production method of hot-rolled ribbed steel bars, in particular to a production method of hot-rolled coiled screws with high height lines of phi 8-phi 10 mm-HRB 400E, which overcomes the defects of the prior art and reduces the production cost.

The technical scheme of the invention is as follows:

the production method of the hot-rolled ribbed steel bar comprises the steps of heating, cogging, rough rolling, intermediate rolling, cooling, pre-finish rolling, cooling, spinning, air-cooling a roller way, collecting and coiling, and slowly cooling, wherein the specification of a wire rod of the ribbed steel bar is phi 8-phi 10 mm; the steel comprises the following chemical components, by mass, 0.20-0.25% of C, 0.40-0.50% of Si, 1.40-1.60% of Mn, less than or equal to 0.045% of P, less than or equal to 0.045% of S, 0.015-0.020% of V, and the balance of Fe and inevitable impurity elements; the key process steps comprise: the tapping temperature is 1070-1130 ℃, the pre-finish rolling temperature is 970-1000 ℃, and the finish rolling temperature is 840-880 ℃; the spinning temperature is 845-875 ℃; the finishing temperature is below the recrystallization temperature of an austenite region; rapidly cooling the roller bed by a fan on an air cooling roller bed, wherein the air volume is 100%; and (4) performing heat preservation by closing the roller way of the heat preservation cover, wherein the temperature of the heat preservation cover is 640-660 ℃, the temperature of the heat preservation cover is 600-620 ℃, and the time of the heat preservation cover is 45-55 s.

The invention principle is as follows: in the temperature range of 840-880 ℃, austenite grains are elongated through rolling deformation, but do not recrystallize. However, a band of strain is generated in the austenite grains, and the end of the band of strain is generally at the grain boundary, and the band of strain in the grains divides the elongated austenite grains as an apparent grain boundary. When austenite is transformed into ferrite, the elongated austenite grain boundary and the apparent grain boundary transformation zone both serve as nucleation sites of ferrite, resulting in refinement of ferrite after transformation. The rolling load of a rough and medium rolling mill and a pre-finish rolling mill is reduced by low-temperature rolling in a finishing mill group, and the service life of the equipment is prolonged.

The invention has the beneficial effects that: a small amount of V is added for microalloy strengthening to improve the yield strength, and the V and the C form carbide which is separated out in the cooling process after rolling to play a role in precipitation strengthening. The tensile strength of the deformed steel bar hot-rolled wire rod is 600-700 MPa, and the yield strength is as follows: 420 to 500MPa, average yield strength of about 450MPa, A_gt>10%, ensuring enough margin. The yield strength is stable, and the performance qualification rate is more than 99%. The invention technically solves the problem that the low-temperature rolling is difficult to be carried out by a torsion rolling mill, reduces the cost on the premise of ensuring no reduction of the productivity and brings higher economic benefit.

Detailed Description

The present invention will be further described with reference to the following examples.

A production method of a set of spiral shell with 8 mm-10 mm phi of high line HRB 400E. The rolling process comprises the following steps: tapping temperature: 1080-1120 ℃, pre-finish rolling 1030-1060 ℃, and finish rolling temperature: 850-870 ℃, spinning temperature: 850-870 ℃, 100% of air quantity of the fan, 640-660 ℃ of temperature of the heat preservation cover, 600-620 ℃ of temperature of the heat preservation cover, 45-55 s of time in the heat preservation cover, and natural cooling. The chemical components of the wire rod of the embodiment of the invention are shown in table 1, and the mechanical properties of the wire rod of the embodiment of the invention are shown in table 2.

Watch (A)

Examples chemical composition of wire rod (Wt%)

Table 2 mechanical properties of the example wire rods

The yield strength of the coiled spiral with the altitude phi of 8 mm to 10mm HRB400E produced by the method is 420 MPa to 500MPa, the Agt is over 10 percent, the yield ratio is over 1.35, the metallographic structure mainly comprises ferrite and pearlite, the performance is stable, the yield strength and the Agt margin are sufficient, and the success of the process has great significance for reducing the production cost and improving the profit of the double-line torsion rolling production line with old equipment.

Claims

1. The production method of the hot-rolled ribbed steel bar comprises the following steps of specification of a wire rod of phi 8 mm-phi 10mm, heating, cogging, rough rolling, intermediate rolling, cooling, pre-finish rolling, cooling, spinning, air-cooled roller way, coil collecting and slow cooling, and is characterized in that: the steel comprises the following chemical components, by mass, 0.20-0.25% of C, 0.40-0.50% of Si, 1.40-1.60% of Mn, less than or equal to 0.045% of P, less than or equal to 0.045% of S, 0.015-0.020% of V, and the balance of Fe and inevitable impurity elements; the key process steps comprise: the tapping temperature is 1070-1130 ℃, the pre-finish rolling temperature is 970-1000 ℃, and the finish rolling temperature is 840-880 ℃; the spinning temperature is 845-875 ℃; the finishing temperature is below the recrystallization temperature of an austenite region; rapidly cooling the roller bed by a fan on an air cooling roller bed, wherein the air volume is 100%; and (4) performing heat preservation by closing the roller way of the heat preservation cover, wherein the temperature of the heat preservation cover is 640-660 ℃, the temperature of the heat preservation cover is 600-620 ℃, and the time of the heat preservation cover is 45-55 s.