Control method for improving inclusion quantity of oxide of large wire energy welding steel

A large input energy welding and control method technology, applied in the field of metallurgy, can solve the problems of difficult formation of uniformly distributed inclusions, reduced number of oxide inclusions, low oxygen level, etc., to improve the performance of large input energy welding and suppress grains The effect of growing up and promoting growth

Inactive Publication Date: 2019-04-05
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

CN201510700964.1 announced the production process of molten iron pretreatment, double blowing converter steelmaking, LF refining, RH vacuum refining, alloy cored wire feeding, and continuous casting. After RH vacuum treatment, oxide metallurgy is carried out, and the steel is controlled at this time. The liquid oxygen level is 5-60ppm, but after deoxidation by LF white slag and RH vacuum treatment, the oxygen level in the steel is very low, and a sufficient amount of oxide inclusions will not be able to be generated without oxygen supplement; CN

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0018] Example 1

[0019] The chemical composition and mass percentage of the steel plate of this embodiment are: C: 0.12%, Si: 0.3%, Mn: 1.3%, Nb: 0.03%, Ti: 0.15%, P: 0.09%, S: 0.005% , The rest is iron and inevitable impurities.

[0020] The steel plate smelting process of this embodiment is hot metal pretreatment→ converter→ LF heating→ RH vacuum refining→ LF refining→ continuous casting. The specific process steps are as follows:

[0021] (1) Converter smelting process: the converter is charged with 105t hot metal after pretreatment, 19t steel scrap, hot metal temperature 1340℃, tapping temperature 1620℃, silicon, manganese and lime are added in sequence at 1 / 3 of tapping, liquid oxygen after tapping Bit 94ppm;

[0022] (2) LF heating process: LF enters the station at a temperature of 1545℃, heats up, and adds slag and Nb alloying during the heating process. When the temperature rises to 1623℃, exit the station;

[0023] (3) RH vacuum refining process: RH entry temperature is 160...

Example Embodiment

[0028] Example 2

[0029] The chemical composition and mass percentage of the steel plate of this embodiment are: C: 0.06%, Si: 0.4%, Mn: 1.7%, Ni: 0.4%, Cr: 0.4%, Cu: 0.23%, Mo: 0.15% , Ti: 0.03%, Nb: 0.04%, V: 0.037%, Zr: 0.0028%, P: 0.07%, S: 0.003%, the rest is iron and unavoidable impurities.

[0030] The steel plate smelting process of this embodiment is molten iron pretreatment→ converter→ LF heating→ VD vacuum refining→ LF refining→ continuous casting. The specific process steps are as follows:

[0031] (1) Converter smelting process: the converter is charged with 110t hot metal after pretreatment, 22t steel scrap, hot metal temperature 1320℃, tapping temperature 1590℃, silicon, manganese and lime are added sequentially at 1 / 3 of the tapping time, liquid oxygen after tapping 53ppm;

[0032] (2) LF heating process: LF enters the station with a temperature of 1539°C, heats up, and adds slag and Ni, Cr, Cu, Mo, Nb, and V alloying during the heating process. When the temperature ...

Example Embodiment

[0038] Example 3

[0039] The chemical composition and mass percentage of the steel plate of this embodiment are: C: 0.05%, Si: 0.07%, Mn: 0.75%, Ni: 0.37%, Cr: 0.40%, Cu: 0.38%, Ti: 0.015% , Ca: 0.0035%, B: 0.004%, P: 0.006%, S: 0.004%, the rest is iron and unavoidable impurities.

[0040] The steel plate smelting process of this embodiment is molten iron pretreatment→ converter→ LF heating→ VD vacuum refining→ LF refining→ continuous casting. The specific process steps are as follows:

[0041] (1) Converter smelting process: the converter is charged with pretreated molten iron 115t, scrap steel 20t, molten iron temperature 1298℃, tapping temperature 1632℃, silicon, manganese and lime are added sequentially at 1 / 3 of tapping, liquid oxygen after tapping Bit 147ppm;

[0042] (2) LF heating process: LF enters the station at a temperature of 1551℃, heats up, adds slag during the heating process and conducts alloying of Ni, Cr and Cu, and exits when the temperature rises to 1600℃;

[004...

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Abstract

The invention discloses a control method for improving inclusion quantity of oxide of large wire energy welding steel. An adopted smelting process flow comprises hot metal pretreatment, converter treatment, LF heating, RH/VD vacuum refining, LF refining and continuous casting; in the converter smelting process, Si and Mn alloys are added in the converter tapping process or after tapping for pre-deoxidation, and the oxygen level of the molten steel is controlled to be 50 ppm-150 ppm; and in the LF refining process, LF refining conducts oxide metallurgy and deep desulfurization, Ti, Mg, Ca, andZr deoxidizers are added to control the oxygen level of the molten steel to be 20 ppm to 100 ppm when oxide metallurgy is carried out. By means of the control method, the inclusion quantity of the oxide of the large wire energy welding steel can be significantly improved, the inclusion surface density is larger than or equal to 800 pieces per square millimetre, and the inclusions smaller than or equal to 3 micrometers in the steel are larger than or equal to 80%.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, in particular to a control method for increasing the amount of oxide inclusions in steel used for high heat input welding. Background technique [0002] With the enlargement of shipbuilding, construction, pressure vessels, oil and gas pipelines and offshore platforms, the steel used is gradually developing towards high strength and thick specifications. In order to improve the welding efficiency and shorten the construction period, the method of large heat input welding is often used in welding. However, after high input energy welding, the structure of the heat-affected zone of steel welding is destroyed, the austenite grain grows significantly, and a coarse-grained zone is formed, resulting in a significant decrease in plasticity and toughness of the heat-affected zone, reducing safety. Therefore, improving the large heat input welding performance of thick steel plates can increase welding ...

Claims

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Application Information

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IPC IPC(8): C21C7/06C21C7/064C21C7/10C21C7/00
CPCC21C7/0006C21C7/06C21C7/064C21C7/10
Inventor 董廷亮吝章国李超李建新孔维明贾国生李玉谦杜琦铭梅东贵李杰
Owner HEBEI IRON AND STEEL
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