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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

AI Technical Summary

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; CN200910187626.7 discloses a A smelting method in which Ti is fed in by wrapping alloy powder with a steel strip to form a steel wire during the casting process, but it is difficult to form evenly distributed inclusions in this method; the smelting method published in CN201310135074.1 is to deoxidize and generate oxidation during the LF refining process inclusions, and then VD vacuum treatment, but this method will remove about 50% of the inclusions in the steel after VD vacuum treatment, and the number of oxide inclusions will be greatly reduced

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

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

[0020] The steel plate smelting process in this embodiment is molten iron 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 loaded with 105t of pretreated molten iron, 19t of scrap steel, the temperature of molten iron is 1340°C, the temperature of tapping is 1620°C, silicon, manganese and lime are added in turn at 1 / 3 of tapping, and the molten steel is oxygenated after tapping. bit 94ppm;

[0022] (2) LF heating process: LF enters the station at a temperature of 1545°C, heats up, adds slag and Nb alloys during the heating process, and exits the station when the temperature rises to 1623°C;

[0023] (3) RH vacuum refining proc...

Embodiment 2

[0029] The chemical composition and mass percentage of the steel plate in this example 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%, and the rest are iron and unavoidable impurities.

[0030] The steel plate smelting process in 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 loaded with 110t of pretreated molten iron, 22t of scrap steel, the temperature of molten iron is 1320°C, the temperature of tapping is 1590°C, silicon, manganese and lime are added in turn at 1 / 3 of tapping, and the molten steel is oxygenated after tapping. bit 53ppm;

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

Embodiment 3

[0039]The chemical composition and mass percentage of the steel plate in this example 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%, and the rest are iron and unavoidable impurities.

[0040] The steel plate smelting process in 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 loaded with 115t of pretreated molten iron, 20t of scrap steel, the temperature of molten iron is 1298°C, and the temperature of tapping is 1632°C. Silicon, manganese and lime are added in turn at 1 / 3 of tapping, and the molten steel is oxygenated after tapping. bit 147ppm;

[0042] (2) LF heating process: LF enters the station at a temperature of 1551°C, heats up, adds slag and alloys Ni, Cr and Cu during the heating process, and leaves the station when the ...

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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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