CN102876960A

CN102876960A - Method for increasing nitrogen content in YQ450NQR1 steels

Info

Publication number: CN102876960A
Application number: CN2012103557107A
Authority: CN
Inventors: 陈爱梅; 张怀军; 刘平; 王云盛; 智建国; 李峰; 金文俊
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd; Inner Mongolia Baotou Steel Union Co Ltd
Priority date: 2012-09-15
Filing date: 2012-09-15
Publication date: 2013-01-16

Abstract

The invention relates to a method for increasing nitrogen content in YQ450NQR1 steels, wherein nitrogen in the produced YQ450NQR1 steels is increased with silicon-manganese nitride alloys under a condition of pretreatment of hot metals, smelting of top and bottom combined blown converters, refining of LF furnace and continuous casting technique; the silicon-manganese nitride alloy consists of the following components by weight percent: 15% of Mn, 43% of Si, 24% of N, 0.3% of C, 0.022% of P, 0.01% of S, the banlance of Fe and the other microelements; the silicon-manganese nitride alloys are added during later period of LF refining; the dosage of the silicon-manganese nitride alloys is 60 kg per 100 t of molten steels. The method has the advantages that the nitrogen content in the silicon-manganese nitride alloys is high and the cost is only 1/7 of alum-nitrogen alloys so as to solve the problem that the price of the alum-nitrogen alloys is high; compared with the method for increasing the nitrogen in the steels with a high-pressure bottom blowing method, the silicon-manganese nitride alloys are used for increasing the nitrogen to make the yield of the nitrogen in the alloys high and stable.

Description

A kind of method that increases YQ450NQR1 nitrogen in steel content

Technical field:

The present invention relates to a kind of method of the YQ450NQR1 of increasing nitrogen in steel content, particularly adopt under hot metal pretreatment → top and bottom combined blown converter smelting → LF stove refining → continuous casting process condition, increase the method for YQ450NQR1 nitrogen in steel content, belong to the field of steel-making that metallurgical industry is produced.

Background technology:

Generally, nitrogen is counted as harmful element in steel, and its existence is usually relevant with the various brittle failure phenomenons of steel, therefore will manage to reduce its content in steel.But nitrogen also has usefulness in steel, and in non-hardened and tempered steel, nitrogen can be used as a kind of micro alloying element and adds in the steel.Nitrogen to carbonitride solid solution in the micro-alloyed steel, precipitation hardening and and crystal grain thinning play an important role.When nitrogen and vanadium, titanium, when niobium exists simultaneously, existing obvious precipitation strength effect has again certain malleableize effect.

In " Jiangxi Metallurgical " published in October, 2004 " research of V-n Microalloying Technology and summary of Application ", adopt nitrogen pick-up in the VN alloy steel, promoted to contain separating out of carbon vanadium nitride in the vanadium steel, strengthened the precipitation strength effect of vanadium, improved the intensity of steel, and be successfully applied in high strength cast iron, non-hardened and tempered steel, the high-strength thick H shaped steel.

In " the process engineering journal " published in June, 2009 " experimental study of high-pressure bottom nitrogen flushing method smelting high-nitrogen steel ", in autoclave, the 18Cr18Mn steel has been carried out the nitrogen pick-up experimental study of bottom blowing nitrogen, having drawn nitrogen pick-up speed reduces in time, bottom blowing nitrogen pick-up effect is better at front 20min, and nitrogen in steel content increases, increases with the bottom blowing nitrogen flow conclusion that raises along with the rising of pressure.

Summary of the invention

The object of the invention provides the method for high and stable, that cost the is low increase YQ450NQR1 nitrogen in steel content of the recovery rate of nitrogen in a kind of alloy.

Technical scheme of the present invention is as follows:

Under hot metal pretreatment → top and bottom combined blown converter smelting → LF stove refining → continuous casting process condition, the YQ450NQR1 steel of producing, adopt nitriding silicon-manganese alloy nitrogen pick-up in steel, the nitriding silicon-manganese alloy component is percentage ratio by weight: Mn:15%, Si:43%, N:24%, C:0.3%, P:0.022, S:0.01%, surplus is Fe and other trace element (the uncontrollable impurity element of being brought into by raw material in the alloy smelting process), nitriding silicon-manganese alloy added in the LF refining later stage, and the add-on of nitriding silicon-manganese alloy is that per 100 tons of molten steel add 60Kg.

The recovery rate average quality percentage ratio of nitrogen is 55% in the method for the present invention, and the mass percent of finished product nitrogen in steel is (100～130) * 10 ^-6

The invention has the beneficial effects as follows: not only nitrogen content is high in the silicomanganese nitrogen alloy, and price only has 1/7 of alum nitrogen alloy, has solved the expensive problem of VN alloy on the market; Adopt nitriding silicon-manganese alloy nitrogen pick-up to compare nitrogen pick-up in the high-pressure bottom nitrogen flushing method steel, the recovery rate of nitrogen is high and stable in the alloy.

Embodiment

The YQ450NQR1 steel that adopts hot metal pretreatment → top and bottom combined blown converter smelting → LF stove refining → continuous casting process to produce, taked following embodiment:

(1) adopt pretreated molten iron, various alloys should toast drying before using;

(2) converter terminal control target: [C] 〉=0.03at%, [P]≤0.025at%, T 〉=1640 ℃; Silicomanganese, ferromanganese and ferrochrome are adopted in tapping pushing off the slag tapping, the ferro-aluminum final deoxygenation, and add-on 2.0kg/t steel adds lime piece 200kg.

(3) refining white slag operation, the refining later stage adds copper coin, nickel plate, vanadium iron, nitrogenize silicomanganese 60Kg, latter stage is fed 100 meters of rare earth silicon calcium lines, 150 meters of silicon-calcium wires in refining, and the soft blow time is not less than 10 minutes after the line feeding.

(4) the continuous casting steel superheating temperature is hanged down and is drawn control (0.5-0.6) m/min less than 30 ℃.

By above-mentioned embodiment, can make the YQ450NQR1 steel of producing under molten iron pre-desulfurization-top and bottom combined blown converter-LF refining-continuous casting process condition, the mass percent of nitrogen in steel can reach (100～130) * 10 ^-6

Claims

1. method that increases YQ450NQR1 nitrogen in steel content, it is characterized in that: under hot metal pretreatment → top and bottom combined blown converter smelting → LF stove refining → continuous casting process condition, the YQ450NQR1 steel of producing, adopt nitriding silicon-manganese alloy nitrogen pick-up in steel, the nitriding silicon-manganese alloy component is percentage ratio by weight: Mn:15%, Si:43%, N:24%, C:0.3%, P:0.022, S:0.01%, surplus is Fe and other trace element, nitriding silicon-manganese alloy added in the LF refining later stage, and the add-on of nitriding silicon-manganese alloy is that per 100 tons of molten steel add the 60Kg alloy.

2. the method for increase according to claim 1 YQ450NQR1 nitrogen in steel content, it is characterized in that: the recovery rate average quality percentage ratio of nitrogen is 55%, and the mass percent of finished product nitrogen in steel is (100～130) * 10 ^-6