Extra-thick plate production method for improving low-temperature impact performance of Q345R core

Abstract

The invention discloses a production method of an extra-thick plate for improving the low-temperature impact performance of a Q345R core. The thickness of a steel plate is 80-150 mm. A steel plate blank comprises the following components in percentage by mass: 0.10-0.16% of C, 1.40-1.60% of Mn, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.1-0.3% of Ni, 0.02-0.04% of Nb, 0.02-0.05% of V and 0.005-0.02% of Ti. In the continuous casting process, the slow pulling speed is set to be 0.50-0.60 m / min, the reduction interval is 0.8-1.6, and the large reduction is 15-20 mm. The method has the advantages that the deviation degree of the core of the Q345R steel plate with the thickness specification of 80-150 mm is improved, the low-temperature impact performance of the core of the Q345R steel plate is improved, and the use performance of customers is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel production, and in particular relates to a method for producing a super-thick plate capable of improving the low-temperature impact performance of a Q345R core. Background Art

[0002] With the rapid development of petrochemical, coal chemical, nuclear power, thermal power and other industries, the demand for high-performance pressure vessel materials is increasing. Q345R steel plate is widely used in these fields due to its excellent mechanical properties, and most project designs require thick plates to have good core impact performance.

[0003] At present, the requirements of low-temperature impact performance are generally met by adding precious metal alloy elements Cr, or tempering treatment is performed on wide and thick plate production lines after normalizing rolling, but these have increased the production costs of enterprises to a certain extent and reduced the market competitiveness of products. In response to this, the patent with application number CN201410271653.3 announced a low-cost Q345R steel plate production method, which can produce Q345R through the set heating, controlled rolling and controlled cooling process, but its products cannot be used in sub-zero low-temperature environments, and when rolling 30mm thick steel plates, controlled rolling must be performed after reheating, and the heating time is 280~400min, which affects the rolling time and increases the rolling cost.

[0004] The existing Q345R steel plate performance improvement relies solely on rolling, without taking advantage of continuous casting. The continuous casting process parameters are rarely disclosed, and the produced steel plates are small in thickness, which generally makes it difficult to meet the core impact performance requirements of 80~150mm extra-thick plates. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of low yield, high cost, long production cycle and low production efficiency of existing Q345R extra-thick plates, and to provide a method for producing extra-thick plates with improved low-temperature impact performance of the core of Q345R, improve the degree of deviation of the core of Q345R steel plates with a thickness of 80~150mm, improve the low-temperature impact performance of the core, and enhance customer performance.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A method for producing an extra-thick plate for improving the low-temperature impact performance of the core of Q345R, wherein the thickness of the steel plate is 80-150 mm, the steel plate blank components and their mass percentages are: C: 0.10-0.16, Mn: 1.40-1.60, P≤0.012, S≤0.003, Ni: 0.1-0.3, Nb: 0.02-0.04, V: 0.02-0.05, Ti: 0.005-0.02; in the continuous casting process, the slow drawing speed is set to 0.50-0.60 m / min, the reduction range is 0.8-1.6, and the maximum reduction is 15-20 mm.

[0007] Furthermore, the compression ratio is maintained at more than 3 times.

[0008] Furthermore, the blank has a cross section of 370-460 mm.

[0009] Furthermore, the heating temperature is 1200-1250° C., and the heating time is 1.0-1.6 min / mm, so as to ensure alloy solid solution and large rolling reduction.

[0010] Furthermore, during the rough rolling with large reduction, it is ensured that the reduction in at least 3 passes is ≥35 mm.

[0011] Furthermore, the steel plate blank composition and their mass percentages are: C: 0.13, Mn: 1.53, P: 0.011, S: 0.002, Ni: 0.23, Nb: 0.035, V: 0.046, Ti: 0.014; in its continuous casting process, the pulling speed is 0.55m / min, the reduction range is 1.0~1.6, and the reduction amount is 18mm.

[0012] Furthermore, the heating temperature for steel tapping is 1230° C., and the heating time is 1.2 min / mm.

[0013] Furthermore, 9 rolling passes were performed, with 6 passes having a reduction of ≥35 mm, of which the maximum pass had a reduction of 44.8 mm.

[0014] In the technical solution of the present invention, for Q345R steel plates with a thickness of 80~150mm, the low-temperature impact performance of the core is improved by optimizing the composition design, improving the continuous casting process and the rolling process, and the full-thickness test impact performance is -20℃≥100J, which reduces the performance rescue amount and improves the customer's performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The rolling pass table for producing the Q345R extra thick plate in the embodiment of the present invention; Figure 2 The mechanical properties table of Q345R extra thick plate in the embodiment of the present invention; Figure 3 The present invention provides a metallographic structure diagram of an extra-thick plate produced by the method of the present invention. DETAILED DESCRIPTION Example

[0016] To make the present invention more clear, a method for producing a particularly thick plate for improving the low-temperature impact performance of the core of Q345R of the present invention is further described below in conjunction with the accompanying drawings. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] In this embodiment, an order of steel grade Q345R and specification of 150*2400mm is taken as an example.

[0018] The design uses a 460mm section and adopts a new design composition scheme. The components of the steel plate billet and their mass percentages are: C: 0.13, Mn: 1.53, P: 0.011, S: 0.002, Ni: 0.23, Nb: 0.035, V: 0.046, Ti: 0.014.

[0019] Among them, in the continuous casting process, the pulling speed is 0.55m / min, the reduction range is 1.0~1.6, and the reduction amount is 18mm.

[0020] The heating temperature of steel is 1230℃ and the heating time is 1.2min / mm.

[0021] Rolling is done in 9 passes, with a reduction of ≥35mm for 6 passes, of which the maximum reduction is 44.8mm. The parameters of each pass are as follows: Figure 1 shown.

[0022] After adopting the method of the present invention, the performance test of the steel plate in the thickness direction is shown as follows: Figure 2 , the metallographic picture of the extra thick plate is as follows Figure 3 The transverse impact absorption energy of -20℃ uncontrolled rolling at high temperature and high pressure is increased from 30-50J in the early stage to more than 100J, and the impact dispersion phenomenon is eliminated.

[0023] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A method for producing extra thick plates for improving the low-temperature impact performance of the core of Q345R, characterized in that: The thickness of the extra thick plate is 80~150mm, and the components and mass percentage of the steel plate billet are: C: 0.10~0.16, Mn: 1.40~1.60, P≤0.012, S≤0.003, Ni: 0.1~0.3, Nb: 0.02~0.04, V: 0.02~0.05, Ti: 0.005~0.02; in the continuous casting process, the slow drawing speed is set to 0.50~0.60m / min, the reduction range is 0.8~1.6, and the maximum reduction is 15~20mm.

2. The method for producing extra thick plates for improving the low temperature impact performance of the core of Q345R according to claim 1, characterized in that: The compression ratio is maintained at more than 3 times.

3. The method for producing a super thick plate for improving the low temperature impact performance of the core of Q345R according to claim 1 or 2, characterized in that: The blank has a cross section of 370-460 mm.

4. The method for producing extra thick plates for improving the low temperature impact performance of the core of Q345R according to claim 3, characterized in that: The heating temperature is 1200-1250° C., and the heating time is 1.0-1.6 min / mm.

5. The method for producing extra thick plates for improving the low temperature impact performance of the core of Q345R according to claim 4, characterized in that: During the rough rolling with large reduction, it is ensured that the reduction amount in at least 3 passes is ≥35mm.

6. The method for producing extra thick plates for improving the low temperature impact performance of the core of Q345R according to claim 5, characterized in that: The steel plate blank has the following components and their mass percentages: C: 0.13, Mn: 1.53, P: 0.011, S: 0.002, Ni: 0.23, Nb: 0.035, V: 0.046, Ti: 0.014; in its continuous casting process, the drawing speed is 0.55 m / min, the reduction range is 1.0-1.6, and the reduction amount is 18 mm.

7. The method for producing extra thick plates for improving the low temperature impact performance of the core of Q345R according to claim 6, characterized in that: The heating tapping temperature is 1230° C. and the heating time is 1.2 min / mm.

8. The method for producing extra thick plates for improving the low temperature impact performance of the core of Q345R according to claim 6, characterized in that: There are 9 rolling passes, with 6 passes with a reduction of ≥35mm, of which the maximum pass has a reduction of 44.8mm.

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