Production method of steel for high-strength tunnel embedded part

Abstract

The invention discloses a production method of steel for a high-strength tunnel embedded part. The production method comprises the following steps: heating; rolling process; the steel for the high-strength tunnel embedded part comprises the following chemical components in percentage by mass: 0.11 to 0.16 percent of C, 0.35 to 0.50 percent of S i, 1.40 to 1.60 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.015 to 0.050 percent of A l, 0.30 to 0.60 percent of Cr, 0.15 to 0.25 percent of Mo, less than or equal to 0.15 percent of Cu, less than or equal to 0.20 percent of N i, 0.08 to 0.12 percent of V, 0.01 to 0.06 percent of T i and less than or equal to 2.0 ppm of [H]. [O] < = 20 ppm; [N] < = 80 ppm; the carbon equivalent (CEV) is less than or equal to 0.54%, and the balance is Fe and impurities. According to the steel for the high-strength tunnel embedded part, the connecting strength and reliability between pipe pieces are improved to a great extent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel rolling, and particularly relates to a production method of high-strength tunnel embedded part steel. BACKGROUND

[0002] An embedded part is a component that is pre-installed (buried) in a concealed project or structure. It is installed when the structure is poured, mainly used for splicing when the upper structure is built, and installation and fixation of external engineering equipment foundation. The embedded part can ensure the smooth progress of the subsequent construction stage and improve the stability and safety of the overall structure.

[0003] A segment embedded part refers to pre-fixing a segment of reinforced concrete on the tunnel wall during tunnel construction to form an integrated tunnel structure. Its main function is to support the soil and share the tunnel load, and also to reduce soil subsidence and increase the stability of the tunnel structure. Common segment embedded parts include epoxy embedded parts, expansion bolt embedded parts, and split anchors.

[0004] An embedded part can firmly connect different structural components or equipment together to form an integrated whole. Before pouring concrete, the embedded part is embedded in the concrete to fix wall panels, ladders, pipes and other components. The embedded part can provide a reliable support point to ensure that the structure remains stable when subjected to external forces. Through reasonable design and arrangement, the embedded part can improve the load-bearing capacity of the structure. The use of embedded parts can also enhance the seismic performance of the structure and improve the safety of the building. At present, after the tunnel is excavated by a shield tunneling machine, a segment assembler assembles prefabricated segments into a ring one by one in the tunnel. When the segment is prefabricated, a spring fixing structure and a magnet adsorption structure are used to fix the embedded part on the end plate of the mold. The DDCI embedded part is used in the tunnel segment for the first time, which replaces the original segment positioning rod connection and greatly improves the connection strength and reliability between the segments. SUMMARY

[0005] The purpose of the application is to provide a production method of high-strength tunnel embedded part steel. The high-strength tunnel embedded part steel produced by the application replaces the original segment positioning rod connection and greatly improves the connection strength and reliability between the segments.

[0006] To solve the above technical problems, the application adopts the following technical solutions:

[0007] The application provides a production method of high-strength tunnel embedded part steel, which comprises the following steps:

[0008] Heating process:

[0009] According to the continuous casting billet specification to determine the heating system, preheating section ≤800℃, heating first section 1100-1150℃, heating second section 1180-1250℃, soaking section 1180-1220℃, slow heating is adopted in the heating section, overburning or overheating is prohibited, at the same time, the continuous casting billet soaking time is ensured to be ≥45min, and the inside and outside temperature of the continuous casting billet is ensured to be uniform;

[0010] Rolling process:

[0011] The continuous casting billet is rolled by the continuous rolling unit, the continuous casting billet rough rolling temperature is controlled to be 1080-1120℃, and the finish rolling temperature is controlled to be 830-870℃; the cold bed adopts the dense arrangement mode, enters the slow cooling pit for slow cooling, and the hot rolling hardness after slow cooling is ensured to be ≤180-220HB;

[0012] The chemical components of the high-strength tunnel embedded part steel are as follows in percentage by mass: C 0.11-0.16%, Si 0.35-0.50%, Mn 1.40-1.60%, P ≤0.020%, S ≤0.020%, Al ≤0.015-0.050%, Cr 0.30-0.60%, Mo 0.15-0.25%, Cu ≤0.15%, Ni ≤0.20%, V 0.08-0.12%, Ti 0.01-0.06%, [H] ≤2.0ppm, [O] ≤20ppm, [N] ≤80ppm, carbon equivalent (CEV) ≤0.54%, and the rest is Fe and inevitable impurities.

[0013] Further, the high-strength tunnel pipe piece embedded part steel hot-rolled square round steel specifications are 150*150mm and φ50-φ100mm, in order to ensure the compression ratio requirement, the continuous casting billet type is 280*380mm and 320*415mm.

[0014] Further, the continuous casting billet adopts Ф850 blooming mill and Ф700mm*3+Ф550mm*4 continuous rolling unit rolling process.

[0015] Further, the continuous casting billet production process is as follows: blast furnace molten iron- molten iron pretreatment-top and bottom combined blowing converter smelting-LF furnace external refining-VD vacuum treatment-continuous casting-slow cooling pit slow cooling.

[0016] Further, the square round steel rolling process is as follows: billet heating-high pressure water phosphorus removal- Ф850 blooming mill- Ф700mm*3+Ф550mm*4 continuous rolling unit rolling-saw cutting (sampling)-slow cooling pit slow cooling-inspection-grinding-bundling-warehousing-shipping.

[0017] Further, it also includes heat treatment: 880℃ oil quenching+630℃ tempering water quenching.

[0018] Further, the steel material is detected by 100% ultrasonic flaw detection according to GB / T 4162 standard, and the products all meet the B-class requirement product qualified.

[0019] Compared with the prior art, the beneficial technical effects of the present application are:

[0020] The hot-rolled square steel and round steel are slowly cooled for more than 36 hours, no surface cracks and other defects are found on the surface of the hot-rolled square steel, and the requirements of the production technical agreement are completely met, and the rolling hardness is between 198-212 HB.

[0021] The steel material is detected by 100% ultrasonic flaw detection according to GB / T 4162 standard, and the products all meet the B-class requirement product qualified. DETAILED DESCRIPTION

[0022] The industrial production process is briefly described as follows:

[0023] Casting blank heating-high pressure water phosphorus removal-Φ850 blooming mill-Φ700mm*3+Φ550mm*4 continuous rolling mill set rolling-saw cutting (sampling)-slow cooling pit slow cooling

[0024] More than 50 heats have been industrially produced, and the specific process parameter control is as follows:

[0025] 1) Heating furnace heating process

[0026] The continuous casting blank is determined according to the thermodynamic formula to determine the reasonable heating time and heating speed,

[0027] Table 1 Heating temperature and soaking time

[0028]

[0029] 2) Rolling process

[0030] In order to ensure product quality and smooth rolling, uniform rolling is adopted, and temperature raising rolling is strictly avoided. The specific parameters are shown in Table 2.

[0031] Table 2 Opening rolling temperature, finishing rolling temperature and entering slow cooling pit temperature

[0032]

[0033] 3) Surface quality

[0034] The hot-rolled square steel and round steel are slowly cooled for more than 36 hours, no surface cracks and other defects are found on the surface of the hot-rolled square steel, and the requirements of the production technical agreement are completely met, and the rolling hardness is between 198-212 HB.

[0035] 4) Performance test

[0036] According to GB / T 2975, longitudinal φ25mm blank samples are taken, heat treatment system is 880℃ oil quenching + 630 tempering water quenching, and its performance is specifically as follows:

[0037] Table 3 Mechanical properties

[0038]

[0039]

[0040] Table 4 Impact test results (heat treatment) Unit: J

[0041]

[0042] Table 5 Brinell hardness test results (heat treatment) Unit: HB

[0043]

[0044] 5) Flaw detection

[0045] Steel materials are detected by 100% ultrasonic flaw detection according to GB / T 4162 standard, and the products all meet the B-grade requirements and are qualified.

[0046] The above-described embodiments are only used to describe the preferred modes of the present application, and do not limit the scope of the present application, and various modifications and improvements to the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application defined by the claims.

Claims

1. A method for producing steel for high-strength tunnel embedded parts, characterized by: include: Heating process: The heating system is determined according to the specifications of the continuous casting billet. The preheating section is ≤800℃, the first heating section is 1100-1150℃, the second heating section is 1180-1250℃, and the soaking section is 1180-1220℃. The heating section adopts slow heating and overheating is prohibited. At the same time, the soaking time of the continuous casting billet is guaranteed to be ≥45min to ensure uniform temperature inside and outside the continuous casting billet. Rolling process: The continuous casting slab adopts the rolling process of the continuous rolling mill. The starting rolling temperature of the continuous casting slab is controlled at 1080-1120℃, and the final rolling temperature is controlled at 830-870℃. The cooling bed adopts a close-packed method and enters the slow cooling pit for slow cooling to ensure that the hot rolling hardness after slow cooling is ≤180-220HB; The chemical composition of the steel for high-strength tunnel embedded parts is as follows by mass percentage: C 0.11-0.16%, Si 0.35-0.50%, Mn 1.40-1.60%, P ≤ 0.020%, S ≤ 0.020%, Al ≤ 0.015-0.050%, Cr 0.30-0.60%, Mo 0.15-0.25%, Cu ≤ 0.15%, Ni ≤ 0.20%, V 0.08-0.12%, Ti 0.01-0.06%, [H] ≤ 2.0 ppm; [O] ≤ 20 ppm; [N] ≤ 80 ppm; carbon equivalent (CEV) ≤ 0.54%; the remainder is Fe and unavoidable impurities.

2. The method for producing steel for high-strength tunnel embedded parts according to claim 1, characterized in that: The specifications of hot-rolled square and round steel used for embedded parts of high-strength tunnel segments are 150×150mm and φ50-φ100mm. In order to ensure the compression ratio requirements, the continuous casting billet shapes used are 280*380mm and 320*415mm.

3. The method for producing steel for high-strength tunnel embedded parts according to claim 1, characterized in that: The continuous casting slab adopts the rolling process of Ф850 slab opening machine and Ф700mm×3+Ф550mm×4 continuous rolling mill group.

4. The method for producing steel for high-strength tunnel embedded parts according to claim 1, characterized in that: The continuous casting billet production process is: blast furnace molten iron - molten iron pretreatment - converter top and bottom blowing smelting - LF refining outside the furnace - VD vacuum treatment - continuous casting - slow cooling in slow cooling pit.

5. The method for producing steel for high-strength tunnel embedded parts according to claim 1, characterized in that: Square and round steel rolling process: billet heating - high-pressure water dephosphorization - Ф850 billet opening machine - Ф700mm×3+Ф550mm×4 continuous rolling mill unit rolling - sawing - slow cooling in cooling pit - inspection - grinding - bundling - warehousing - delivery.

6. The method for producing steel for high-strength tunnel embedded parts according to claim 1, characterized in that: It also includes heat treatment: 880℃ oil quenching + 630℃ tempering water quenching.

7. The method for producing steel for high-strength tunnel embedded parts according to claim 1, characterized in that: Steel is 100% ultrasonically tested in accordance with GB / T4162 standard, and all products meet Class B requirements and are qualified.

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