CN107794355B - A production method of 250mm extra-thick high-strength steel for offshore platforms - Google Patents

Abstract

The invention provides a production method of 250mm super-thick high-strength steel for an ocean platform, which specifically comprises the following steps: 1. a multi-angle ingot forging stock is used as a blank, and the size of the blank is 350 x 2500 x 5000 mm. 2. The weight percentage of the chemical components is as follows: 0.10-0.15% of C, Si: 0.35-0.45%, Mn: 1.38-1.45%, Nb 0.30-0.35%, P is less than or equal to 0.01%, S is less than or equal to 0.003%, Ti: 0.002-0.005%, Cr: 0.03-0.06%. The produced 250mm extra-thick high-strength steel EH36-Z35 for the ocean platform has all performance indexes meeting ideal requirements.

Description

A production method of 250mm extra-thick high-strength steel for offshore platforms

technical field

The invention relates to a production method of 250mm extra-thick high-strength steel for offshore platforms.

Background technique

Offshore steel is a key material in the construction of marine structures. In the process of developing offshore oil and gas resources and building offshore platforms, in order to improve the safety of platforms, the application of large-thickness and ultra-high-strength steels is becoming more and more common, and the strength is increasing. At present, the country still needs to import a large amount of steel, which is the steel that is urgently needed by the domestic offshore industry.

The production process of offshore steel is strict, requires high equipment stability, and is difficult to develop. It requires high low-temperature impact toughness, good resistance to lamellar tearing, and seawater corrosion resistance. At present, only Wugang and Baosteel have supply performance in China. .

Contents of the invention

The object of the invention is to provide a production method of 250mm extra-thick high-strength steel for offshore platforms.

To achieve the above object, the present invention is achieved through the following technical solutions:

A method for producing 250mm extra-thick high-strength steel for offshore platforms, specifically including the following:

1. The multi-angle ingot forging blank is used as the blank, and the blank size is 350*2500*5000mm.

2. The weight percentage of chemical composition is: C: 0.10-0.15%, Si: 0.35-0.45%, Mn: 1.38-1.45%, Nb: 0.30-0.35%, P≤0.01%, S≤0.003%, Ti: 0.002- 0.005%, Cr: 0.03-0.06%.

3. The technological process is: ingot heating - descaling - TMCP rolling - straightening - slow cooling pit heating and slow cooling - normalizing - flaw detection - flame cutting - inspection, inspection - storage.

4. Put the multi-angle ingot forging billet into a furnace at 700°C for 2 hours, heat at 700-1100°C for 3 hours, and soak at 1100°C for about 3 hours.

5. Rolling process: general rolling, cross rolling to 3000mm, and then 1-2 passes of longitudinal rolling to the thickness of the finished product.

6. Cooling control process: adopt reciprocating weak cooling mode, the cooling time of cooling is more than 15min, the specific setting is 780-820°C for starting cooling, 480-580°C for final cooling, and 1/4 of the plate thickness in the temperature control range The average cooling rate of the position is 0.3-1.0°C/s.

7. Slow cooling process: After rolling, the steel plate is put into the slow cooling pit, heated to 500°C, and kept at 500°C for 48 hours, and then cooled to room temperature with the furnace and then released from the furnace.

8. Normalizing process: Furnace loading at 925°C, heating rate: 1.5min/mm, holding time: 150min, and air-cooled after leaving the furnace.

Compared with prior art, the beneficial effect of the present invention is:

Through the above technical solutions, the produced 250mm extra-thick high-strength offshore platform steel EH36-Z35 has all performance indicators meeting the ideal requirements. Its mechanical properties are: yield strength 351MPa, tensile strength 524MPa, elongation 34.6%, -40°C impact average 144-286, Z-direction average 46, the performance meets the product requirements, and the flaw detection is qualified.

Detailed ways

The technical solution of the present invention will be described in further detail below through specific examples.

A method for producing 250mm extra-thick high-strength steel for offshore platforms, specifically including the following:

1. The multi-angle ingot forging blank is used as the blank, and the blank size is 350*2500*5000mm.

2. The weight percentage of chemical composition is: C: 0.10-0.15%, Si: 0.35-0.45%, Mn: 1.38-1.45%, Nb: 0.30-0.35%, P≤0.01%, S≤0.003%, Ti: 0.002- 0.005%, Cr: 0.03-0.06%.

3. The technological process is: ingot heating - descaling - TMCP rolling - straightening - slow cooling pit heating and slow cooling - normalizing - flaw detection - flame cutting - inspection, inspection - storage.

4. Put the multi-angle ingot forging billet into a furnace at 700°C for 2 hours, heat at 700-1100°C for 3 hours, and soak at 1100°C for 3 hours.

5. Rolling process: general rolling, cross rolling to 3000mm, and then 1-2 passes of longitudinal rolling to the thickness of the finished product.

6. Cooling control process: adopt reciprocating weak cooling mode, the cooling time of cooling is more than 15min, the specific setting is 780-820°C for starting cooling, 480-580°C for final cooling, and 1/4 of the plate thickness in the temperature control range The average cooling rate of the position is 0.3-1.0°C/s.

7. Slow cooling process: After rolling, the steel plate is put into the slow cooling pit, heated to 500°C, and kept at 500°C for 48 hours, and then cooled to room temperature with the furnace and then released from the furnace.

8. Normalizing process: Furnace loading at 925°C, heating rate: 1.5min/mm, holding time: 150min, and air-cooled after leaving the furnace.

Claims (1)

1. A production method of 250mm extra-thick high-strength steel for offshore platforms, characterized in that it specifically includes the following: 1) The multi-angle ingot forging blank is used as the blank, and the blank size is 350*2500*5000mm; 2) The weight percentage of chemical composition is: C: 0.10-0.15%, Si: 0.35-0.45%, Mn: 1.38-1.45%, Nb: 0.30-0.35%, P≤0.01%, S≤0.003%, Ti: 0.002- 0.005%, Cr: 0.03-0.06%; 3) The technological process is: ingot heating - descaling - TMCP rolling - straightening - slow cooling pit heating and slow cooling - normalizing - flaw detection - flame cutting - inspection, inspection - storage; 4) The multi-angle ingot forging blank is placed in a furnace at 700°C for 2 hours, heated at 700-1100°C for 3 hours, and soaked at 1100°C for 3 hours; 5) Rolling process: general rolling, cross rolling to 3000mm, and then 1-2 passes of longitudinal rolling to the thickness of the finished product; 6) Cooling control process: adopt reciprocating weak cooling mode, the cooling time of cooling is more than 15min, the specific setting is the start cooling temperature 780-820 ℃, the final cooling temperature is 480-580 ℃, the temperature control interval controls the plate thickness 1/4 The average cooling rate of the position is 0.3-1.0°C/s; 7) Slow cooling process: After rolling, the steel plate is put into the slow cooling pit, heated to 500°C, and kept at 500°C for 48 hours, then cooled to room temperature with the furnace and then released from the furnace; 8) Normalizing process: Furnace loading at 925°C, heating rate: 1.5min/mm, holding time: 150min, and air-cooled when out of the furnace.