Low-temperature high-toughness V-N alloyed ship plate steel and manufacturing method thereof

A manufacturing method and high-toughness technology, which is applied in the production field of low-temperature high-toughness V-N alloyed ship plate steel, can solve problems such as low low-temperature impact toughness, failure to meet demand, and low tensile strength, so as to reduce carbon content and increase profits Space, the effect of improving welding performance

Active Publication Date: 2014-06-25
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] For example, the patent with the publication number CN101701326A discloses a high-toughness and large-thickness ship plate steel with a yield strength of 355MPa. Its impact energy at -20°C reaches more than 100J, but its chemical composition contains valuable alloying elements Mo, Ni, etc.
resulting in higher production costs
[0007] The patent with publication number CN101876033A discloses a low-temperature high-toughness ship plate steel. The ship plate steel disclosed in this patent has high low-temperature impact toughness, and the longitudinal impact energy at -60°C can reach more than 250J, but its tensile strength is relatively low. Low, about 480MPa
Far from meeting the needs of modern large ships
[0008] The patent with the publication number CN102199724A discloses an alloy weight-reducing ship plate steel with a yield strength of 355MPa. The ship plate steel disclosed in the patent has high tensile strength, but its low-temperature impact toughness is low, and Charpy impact energy at -20°C Minimum is 34J

Method used

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  • Low-temperature high-toughness V-N alloyed ship plate steel and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Example 1: The composition of the ship plate steel shown in Table 1 was smelted in a 200 kg vacuum induction melting furnace. During the smelting process, after the refining is completed, nitrogen gas is introduced into the vacuum smelting furnace, and the nitrogen pressure is controlled at 450Pa. The molten steel was cast into an 80Kg ingot. The ingot was placed in a high-temperature resistance furnace, heated to 1150°C, kept for 1.5h, and rolled into a steel plate with a thickness of 20mm in 5 passes on an experimental rolling mill, with a total reduction rate of 85% and a rolling temperature of 1050°C. Then it is controlled and cooled, the cooling temperature is 850°C, and the reddening temperature is 570°C. The metallographic structure of the steel plate is figure 1 shown.

[0038] The obtained steel plate was subjected to mechanical testing, and its mechanical properties are shown in Table 2.

Embodiment 2

[0039]Example 2: The composition of the ship plate steel shown in Table 1 was smelted in a 200 kg vacuum induction melting furnace. During the smelting process, after the refining is completed, nitrogen gas is introduced into the vacuum smelting furnace, and the nitrogen pressure is controlled at 440Pa. The molten steel was cast into an 80Kg ingot. The ingot was placed in a high-temperature resistance furnace, heated to 1200 °C, kept for 1 h, and rolled into a steel plate with a thickness of 15 mm in 6 passes on an experimental rolling mill, with a total reduction rate of 90% and a rolling temperature of 1130 °C. Then it is controlled and cooled, the cooling temperature is 900°C, and the reddening temperature is 710°C. The metallographic structure of the steel plate is figure 2 shown.

[0040] The obtained steel plate was subjected to mechanical testing, and its mechanical properties are shown in Table 2.

Embodiment 3

[0041] Example 3: The composition of the ship plate steel shown in Table 1 was smelted in a 200 kg vacuum induction melting furnace. During the smelting process, after the refining is completed, nitrogen gas is introduced into the vacuum smelting furnace, and the nitrogen pressure is controlled at 455Pa. The molten steel was cast into an 80Kg ingot. The ingot was placed in a high-temperature resistance furnace, heated to 1200°C, kept for 2.5h, and rolled into a steel plate with a thickness of 20mm in 5 passes on an experimental rolling mill, with a total reduction rate of 85% and a rolling temperature of 1065°C. Then it is controlled and cooled, and the cooling temperature is 865°C, and the reddening temperature is 700°C. The metallographic structure of the steel plate is image 3 shown.

[0042] The obtained steel plate was subjected to mechanical testing, and its mechanical properties are shown in Table 2.

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Abstract

The invention discloses a low-temperature high-toughness V-N alloyed ship plate steel and a manufacturing method thereof. The steel comprises the following chemical elements in percentage by weight: 0.055% to 0.15% of C, 0.1% to 0.25% of Si, 1.55% to 1.65% of Mn, 0.035% to 0.045% of V, 0.003% to 0.013% of Ti, 0.006% to 0.0095% of N, not more than 0.02% of P, not more than 0.02% of S, not more than 0.03% of Als, and the balance being Fe and inevitable impurities. The steel is prepared by the following steps: smelting in vacuum environment, introducing nitrogen gas into the furnace after the refinement, casting ingots, heating the ingots to a temperature of 1150 to 1250 DEG C, and maintaining the temperature for 0.5 to 2.5 hours; wherein the rolling temperature is 1050 DEG C to 1130 DEG C, the cooling temperature is 850 DEG C to 950 DEG C, and the re-reddening temperature is 500 to 800 DEG C. The formula of the steel is re-designed, thus the carbon content of the steel is effectively reduced, and the welding performance of the steel is improved. At the same time the cheap nitrogen element is fully utilized to optimize the precipitate of V, so the strength and toughness of the steel are both improved, and the cost of the steel is reduced too.

Description

technical field [0001] The invention belongs to the production technology of high-strength and toughness steel plate, in particular to a production technology of low-temperature and high-toughness V-N alloyed ship plate steel. Background technique [0002] Ship plate steel is one of the main varieties of medium and heavy plate. The continuous development of shipbuilding and offshore oil industries and the trend of large-scale and high-speed ships have increased the demand for high-strength and high-toughness ship plate steel; at the same time, With the development of the world economy and the growth of trade, the demand for low-cost shipping methods continues to grow. In order to meet the service performance of ships under various conditions, people's requirements for the performance of ship plate steel are becoming more and more stringent; the general strength of the ship plate can no longer meet the needs of the hull, with high strength, high toughness, high quality grade ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/14C21D8/02
Inventor 李广龙赵坦李文斌原思宇王勇孙殿东郭晓波钟莉莉高冰罗志华
Owner ANGANG STEEL CO LTD
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