Steel plate for ship and segregation-preventing production method thereof

A production method and a technology for ships, which are applied in the production field of steel plates for ships and avoid segregation, can solve the problems of low pass rate of steel grades, impact samples, fracture separation, etc., achieve improvement of steel plate segregation, increase heating temperature, avoid The effect of segregation formation

Inactive Publication Date: 2020-10-13
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the fracture separation of tensile and impact specimens often occurs in the mechanical performance test of the existing steel for ships, and sometimes the fracture separation rate of the specimen is even as high as 60-70%, resulting in a low qualified rate of steel types.
[0003] The reason is mainly due to the inhomogeneous distribution of alloy elements in the steel obtained by the existing production method, which leads to grain segregation.

Method used

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  • Steel plate for ship and segregation-preventing production method thereof
  • Steel plate for ship and segregation-preventing production method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Embodiment 1: After the billet continuous casting is cut, it is put into the heat preservation pit, and the temperature of the heat preservation pit is controlled at 650° C., and the heat preservation is carried out for 72 hours.

[0025] Put the 220mm thick continuous casting billet into the heating furnace for reheating, the heating temperature is 1200°C, the total time in the furnace is 352min, the soaking time is 73min, and rolled into a rolled piece of 12×2000×Lmm (thickness, width, length), and finally The rolling temperature is 900°C, and the redness temperature is 680°C. The steel plate is qualified by NB / T 47013 T1T1 flaw detection.

[0026] The 12×2000×8000mm steel plate was quenched and tempered at high temperature, the quenching heating temperature was 900°C, the total quenching time in the furnace was 30min, the tempering heating temperature was 665°C, and the total tempering time in the furnace was 90min.

[0027] The test results of mechanical properties...

Embodiment 2

[0028] Example 2: Similarly, after the continuous casting and cutting of the blank, it is put into the heat preservation pit, and the temperature of the heat preservation pit is controlled at 650° C., and the heat preservation is carried out for 80 hours.

[0029] Put the 220mm thick continuous casting billet into the heating furnace for reheating, the heating temperature is 1240°C, the total time in the furnace is 385min, the soaking time is 83min, and rolled into a rolled piece of 15×2000×Lmm (thickness, width and length). The rolling temperature is 920°C, and the redness temperature is 675°C. The steel plate is qualified by NB / T 47013 T1T1 flaw detection.

[0030] The 15×2000×8000mm steel plate was quenched and tempered at high temperature, the quenching heating temperature was 920°C, the total quenching time in the furnace was 35min, the tempering heating temperature was 673°C, and the total tempering time in the furnace was 106min.

[0031] The test results of mechanical...

Embodiment 3

[0032] Embodiment 3: After the billet continuous casting is cut, it is put into the heat preservation pit, and the temperature of the heat preservation pit is controlled at 660° C., and the heat preservation is carried out for 83 hours.

[0033] Put the 220mm thick continuous casting billet into the heating furnace for reheating, the heating temperature is 1230°C, the total time in the furnace is 390min, the soaking time is 60min, and rolled into a rolled piece of 16×2000×Lmm (thickness, width, length). The rolling temperature is 910°C, and the redness temperature is 670°C. The steel plate is qualified by NB / T 47013 T1T1 flaw detection.

[0034] The 16×2000×8000mm steel plate was quenched and tempered at high temperature, the quenching heating temperature was 910°C, the total quenching time in the furnace was 20min, the tempering heating temperature was 660°C, and the total tempering time in the furnace was 110min.

[0035] The test results of mechanical properties are: yield...

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Abstract

The invention discloses a steel plate for a ship and a segregation-preventing production method thereof. According to the steel plate for the ship, by conducting sufficient heat preservation at the temperature over 650 DEG C on a blank in the production process, hydrogen in the blank is fully diffused; the heating temperature is raised, a long heating time is adopted, so that alloy elements in thesteel are fully diffused, segregation is prevented from being formed, internal defects such as central segregation are relieved, and the form of impurities is effectively improved; then quenching andhigh-temperature tempering are conducted, the structure of the steel plate is re-austenitized, precipitation of a second phase is effectively controlled, so that more uniform and finer tempered sorbite structure is obtained, and steel plate segregation is further relieved. After dynamic inspection, the performance of the steel plate meets the requirements that the yield strength is larger than orequal to 390 MPa, the tensile strength is 530-600 MPa, the ductility is larger than or equal to 21%, the impact value at minus 40 DEG C is larger than or equal to 200 J, and the separation cracking length of tensile fracture and impact fracture is 0.

Description

technical field [0001] The invention relates to a steel and a production method thereof, in particular to a steel plate for ships and a production method for avoiding segregation thereof. Background technique [0002] In recent years, with the continuous development of the shipbuilding industry, the demand for ship plates has increased, and higher requirements have been put forward for ship steel. Therefore, steel for ships needs to undergo strict mechanical performance inspections when they are delivered. However, the fracture separation of tensile and impact specimens often occurs in the mechanical performance test of the existing steel for ships, and sometimes the fracture separation rate of the specimens is even as high as 60-70%, resulting in a low qualified rate of steel grades. [0003] The reason is mainly due to the inhomogeneous distribution of alloy elements in the steel obtained by the existing production method, which leads to grain segregation. Therefore, red...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/42C21D8/02C21D1/18
CPCC22C38/02C22C38/04C22C38/42C21D8/0226C21D8/0247C21D1/18
Inventor 邢萍赵荣贵
Owner NANJING IRON & STEEL CO LTD
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