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Production method of low-temperature steel plate capable of being welded by high heat input

A large heat input welding and production method technology, applied in the direction of improving process efficiency, etc., can solve the problems of deterioration of toughness, lack of research on the order and influence of alloy addition, and achieve the effect of improving welding performance

Active Publication Date: 2012-11-07
INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1) The most important process parameters in this technology are not studied, such as the type of alloy to be added, the way of alloy addition, the order of alloy addition, the timing of alloy addition (namely, the temperature of molten steel before alloy addition, the dissolved oxygen content in molten steel ), etc.; the above process parameters directly determine the type, size and surface density of the final formed oxide, which in turn directly determines the welding performance of the final steel plate product
[0005] 2) Deep deoxidation is done by adding aluminum blocks in converter tapping, which will introduce a certain amount of solid solution aluminum in molten steel; since aluminum is a strong deoxidizing element, and its affinity with oxygen is greater than that of other alloy elements, the existence of aluminum in molten steel has a serious impact on The chemical reaction between the addition of strong deoxidizer and molten steel leads to the formation of larger alumina or composite oxides mainly composed of alumina in molten steel, which loses the purpose of improving the welding performance of steel plates by pinning austenite grain boundaries
However, due to the need for a certain amount of S in this technology, it is easy to cause coarse sulfide and deteriorate the toughness.

Method used

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  • Production method of low-temperature steel plate capable of being welded by high heat input
  • Production method of low-temperature steel plate capable of being welded by high heat input
  • Production method of low-temperature steel plate capable of being welded by high heat input

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Experimental program
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Effect test

Embodiment 1

[0022] The molten steel smelting process is as follows:

[0023] Hot metal pretreatment→180t combined blowing converter smelting→LF refining→RH refining→wire feeding→continuous casting. During the converter smelting process, the ratio of the amount of molten iron for furnace charging to clean steel scrap is 7.5, the temperature of molten iron is 1400°C, S≤0.003% by weight, the basicity of slag is 3.5, and the ratio of MgO is 9.0%; Ferromanganese, ferrosilicon, lime. White slag is produced during the LF refining process. At the same time, the molten steel is oxygenated, ferroboron is added, diffusion deoxidized, and molten steel samples are taken for composition fine-tuning. In the RH vacuum treatment stage, measure oxygen and control the oxygen content at 10-100ppm before adding ferrotitanium. After the net circulation, the temperature of the molten steel is 1570-1600°C and the oxygen content is 20-80ppm. Feed 400 meters of magnesium alloy cored wire into the water, the diam...

Embodiment 2

[0031] The molten steel smelting process is as follows:

[0032]Hot metal pretreatment→180t combined blowing converter smelting→LF refining→RH refining→wire feeding→continuous casting. During the converter smelting process, the ratio of the amount of molten iron used for charging to clean steel scrap is 7, the temperature of molten iron is 1450°C, S≤0.003% by weight, the basicity of slag is 3.5, and the ratio of MgO is 9.0%; Ferromanganese, ferrosilicon, lime. During the LF refining process, white slag is produced, and ferroboron is added. At the same time, the molten steel is subjected to constant oxygen, diffusion deoxidation, and liquid steel samples are taken to fine-tune the composition. The tapping temperature is controlled at 1620-1640°C. In the stage of RH vacuum treatment, when the oxygen content of the molten steel meets the requirements of 10-100ppm, add ferrotitanium, and then measure the oxygen. Feed 350 meters of magnesium alloy cored wire with a diameter of 14...

Embodiment 3

[0040] The molten steel smelting process is as follows:

[0041] Hot metal pretreatment→180t combined blowing converter smelting→LF refining→RH refining→wire feeding→continuous casting. During the converter smelting process, the ratio of the amount of molten iron used for charging to clean steel scrap is 8, the temperature of the molten iron is 1430°C, S≤0.003% by weight, and the basicity of the slag is 3.5; ferromanganese and ferrosilicon are added sequentially when tapping about 35 tons of steel ,lime. White slag is produced during the LF refining process. At the same time, oxygen is fixed for molten steel, ferroboron is added, and the composition is fine-tuned. The tapping temperature is controlled at 1620-1640 °C. In the RH vacuum stage, when the oxygen content of the molten steel meets the requirements of 10-100ppm, add ferrotitanium, and then measure the oxygen. After the oxygen content of the molten steel meets 20-80ppm, feed it into the molten steel for 380 meters at ...

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Abstract

The invention relates to a production method of a low-temperature steel plate capable of being welded by high heat input. The production method includes the steps of hot metal pretreatment, combined blown converter smelting, ladle furnace (LF) refining, RH refining, wire feeding and continuous casting, white slags are produced by LF refining, ferrotitanium is added at an RH station, vacuum breaking is performed when the temperature of molten steel reaches 1570-1600 DEG C and the content of dissolved oxygen in the molten steel reaches 20-80ppm, magnesium alloy or calcium alloy cored wires which are 200-400 meters long are fed into the molten steel at the speed of 4-6m per second and subjected to continuous casting to obtain continuous casting billets, and the continuous casting billets aresubjected to reheating and heat preservation, controlled rolling and controlled cooling to obtain the low-temperature steel plate capable of being welded by the high heat input. The steel plate is good in low-temperature toughness, Charpy impact energy of the steel plate at the temperature of -80 DEG C is larger than 47J, after the steel plate is welded by the heat input of 500-600 kJ / cm, Charpy impact energy of heat affect zones at the temperature of -60 DEG C is larger than 47J, and the steel plate can be widely applied to energy construction engineering fields of ships, low-temperature pressure containers, ocean platforms and the like.

Description

technical field [0001] The invention belongs to the field of manufacturing low-temperature steel medium-thick plates with excellent welding performance, and in particular relates to a production method of low-temperature steel plates that can be welded with large heat input. Background technique [0002] Due to the continuous improvement of energy demand, the demand for low-temperature steel in the fields of shipbuilding, bridges, natural gas pipelines, and offshore platforms is also increasing; the use of welding steel plates with a large heat input (≥200kJ / cm) can significantly improve welding efficiency and shorten construction. Therefore, low-temperature steel that can be welded with large heat input has been widely used in the field of energy construction. [0003] Industrial mass production of steel plates that can be welded with large heat input usually includes processes such as molten steel smelting and finished steel plate rolling (or including heat treatment). Th...

Claims

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Application Information

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IPC IPC(8): C21D8/02C21C7/06C22C38/14
CPCY02P10/20
Inventor 张宇潘鑫李小宝
Owner INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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