JPS60243214A - Manufacture of alloy steel containing nitrogen - Google Patents

Abstract

PURPOSE:To obtain nitrogen-contg. alloy steel inexpensively in stable yield of nitrogen addition by specifying the immersion depth of a lance for introducing gaseous nirogen and the flow rate of gaseous nitrogen and introducing gaseous nitrogen after VOD-refining the alloy steel which has been subjected to refining. CONSTITUTION:The result of research about the effect for the yield of nitrogen addition and operating conditions at the following period is shown in the figures wherein the addition conditions of gaseous nitrogen are changed in the component regulating period after VOD-refining stainless steel, for example, SUS304. Still more, in this case, the immersion depth into the molten steel of a lance for introducing gaseous nitrogen is regulated to 60-85% of the depth of the molten steel. Gaseous nitrogen is introduced from the lance to obtain nitrogen- contg. allow steel by regulating the flow rate of gaseous nitrogen to 0.30- 0.045Nm<3>/min per ton of molten steel together with the depth of immersion. As a result, the yield of nitrogen addition is improved and also the scattering of molten steel is diminished and furthermore the fusion wear of side wall refratory of the ladle can be reduced.

Description

【発明の詳細な説明】 本発明は含窒素合金鋼の製造方法忙関し、特Ｋ　ＶＯＤ
精錬後の合金鋼溶湯に窒素導入用ランスな用い窒素ガス
を適正な条件で、安く安定した窒素添加歩留を得る窒素
添加方法に関するものである。[Detailed Description of the Invention] The present invention relates to a method for manufacturing nitrogen-containing alloy steel, and a special method for manufacturing nitrogen-containing alloy steel.
The present invention relates to a method of adding nitrogen to a molten alloy steel after refining, using a lance for introducing nitrogen gas under appropriate conditions to obtain a stable nitrogen addition yield at a low cost.

従来、含窒素合金鋼を製造する方法として。Conventionally, as a method for producing nitrogen-containing alloy steel.

電気炉やＡＯＤ　Ｗ錬による場合は比較的容易であるが
、最近、合金鋼の精錬に常用されている真空下で精錬す
るＶＯＤ精錬においては、真空下で脱賭現象を生じ、真
空精錬後の成分調整期に含窒素合金例えば窒化フエａ／
四ム、窒化フェロマンガン、窒化７エマンガンなどによ
り窒素を添加していた。It is relatively easy to use an electric furnace or AOD W refining, but recently, in VOD refining, which is commonly used for refining alloy steel under vacuum, a gambling phenomenon occurs under vacuum, and the During the component adjustment period, nitrogen-containing alloys such as nitrided Fea/
Nitrogen was added using 4M, ferromanganese nitride, 7Emanganese nitride, etc.

しかしながら、この方法によるときは溶鋼上′が変動す
る欠点がある．。又窒素添加だけの目的に，前述の如き
含窒素合金を添加することは高価なりロムやマンガンを
含有せしめることとなりコストアップとなっていた。さ
らにクロムやマンガンやカーボンの含有量が規制される
鋼種については窒化フエロクロム、窒化７エ胃マンガン
、窒化電解マンガンは使用できない。又操業面、品質面
においても、多量の窒化合金を添加することは温度降下
の増大や精錬後の溶鋼．に未精錬合金が入ることによる
品質低下の問題を招いていた。However, this method has the disadvantage that the molten steel surface varies. . Furthermore, adding a nitrogen-containing alloy such as the one described above for the sole purpose of adding nitrogen is expensive and requires the inclusion of ROM or manganese, resulting in an increase in cost. Further, for steel types where the content of chromium, manganese, and carbon is regulated, ferrochrome nitride, 7-gastric manganese nitride, and electrolytic manganese nitride cannot be used. In addition, in terms of operation and quality, adding a large amount of nitriding alloy will increase the temperature drop and cause problems in the molten steel after refining. The presence of unrefined alloys in the process led to problems with quality deterioration.

本発明は上記の従来方法の問題を改善するととを、目的
としたもので、合金鋼を溶製しｖＯＤｗｊ錬した後窒素
を添加するに当り、窒素ガス導入用ランスな溶鋼内に浸
漬してその浸漬深さを溶鋼深さの６０％以上８５％以下
となるようにし、而も窒素ガスを０．０３枳上０．０４
５以下Ｎｌｌ３／分溶鋼トンの流量で大気下において吹
込むことにより含窒素合金鋼を展進する方法に関するも
のである。The purpose of the present invention is to improve the problems of the above-mentioned conventional method, and when adding nitrogen after melting alloy steel and vODwjing, it is immersed in the molten steel using a lance for introducing nitrogen gas. The immersion depth should be 60% or more and 85% or less of the molten steel depth, and nitrogen gas should be added by 0.03 to 0.04.
The present invention relates to a method for developing nitrogen-containing alloy steel by blowing in the atmosphere at a flow rate of 5 or less Nll3/ton of molten steel.

本発明者らは安価な窒素源として窒素ガスに着眼したが
、ＶＯＤ精錬忙おいてポーラスプラグを通し底吹きでＮ
ガスを添加するには、現在市販されているポーラスプラ
グでは非常に流量が小さく長時間を要し溶鋼の温度低下
が大きいので、窒素ガス導入用ランスな用い上吹きで多
量に窒素を添加することを考え、安定かつ高い窒素添加
歩留を得るため窒素ガス添加条件について各種の試験を
行ない、その結果を以下忙示す。The present inventors focused on nitrogen gas as an inexpensive nitrogen source, but during VOD refining, N was bottom-blown through a porous plug.
To add gas, with the porous plugs currently available on the market, the flow rate is very low and it takes a long time, and the temperature of the molten steel drops significantly. Therefore, it is recommended to use a lance for introducing nitrogen gas and add a large amount of nitrogen by top blowing. In order to obtain a stable and high nitrogen addition yield, various tests were conducted regarding nitrogen gas addition conditions, and the results are summarized below.

ＳＵＳ　３０４のステンレス鋼（１８，５％（ｊｒ　−
８，５％Ｎｉ）　ｓ　５　ＴをＶＯＤ精錬精錬分成分調
整期素ガス添加条件を変化させた時の窒素添加歩留、操
業条件への影響について調査し、第１図に窒素ガス流量
を０．０１５’　Ｎｔａ５／分溶鋼トンから０．０５３
　Ｎ■３／分溶鋼トンまで変化させた時の窒素添加歩留
（１）、溶鋼飛散状況（２）及び取鍋側壁耐火物溶損状
況（３）の推移を示す。SUS 304 stainless steel (18.5% (jr-
8.5%Ni) s 5 T during VOD refining and refinement component adjustment.The effect on the nitrogen addition yield and operating conditions when changing the element gas addition conditions was investigated, and Figure 1 shows the nitrogen gas flow rate at 0. .015' Nta5/min molten steel ton to 0.053
The changes in nitrogen addition yield (1), molten steel scattering status (2), and ladle side wall refractory erosion status (3) are shown when changing the rate up to N3/min molten steel tons.

なおこの時の窒素ガス導入用ランスの浸漬深さは溶鋼深
さの７５％である。The immersion depth of the nitrogen gas introduction lance at this time was 75% of the molten steel depth.

第１図より明らかなように、窒素添加歩留は窒素ガス流
量が０’、０３．ＮＩＩ’　７分溶鋼トンを超えると若
干向上するが短時間で窒素添加するには窒素ガス流量を
多くした方がよいのは当然である。しかしながら窒素ガ
ス流量が０．０４５　Ｈｉｍ’／分溶鋼トン以上忙なる
と溶鋼の飛散は多くなり操業困難な状態となる。又取鍋
側壁耐火物は窒素ガス流量が０．０４５　Ｈｔｔｒ３／
分溶鋼トン以上となると溶損が大きくなるので、この結
果に基き本発明においては窒素ガス流量はｏ、ｏ　ｓ　
。As is clear from FIG. 1, the nitrogen addition yield is the same as the nitrogen gas flow rate of 0', 03. NII' There is a slight improvement when exceeding 7 minutes of molten steel tons, but it is natural that it is better to increase the nitrogen gas flow rate in order to add nitrogen in a short time. However, if the nitrogen gas flow rate exceeds 0.045 Him'/min ton of molten steel, the amount of molten steel scattering increases, making operation difficult. Also, the nitrogen gas flow rate of the ladle side wall refractory is 0.045 Httr3/
If the amount exceeds a ton of molten steel, the erosion loss will increase, so based on this result, in the present invention, the nitrogen gas flow rate is o, o s
.

Ｈａ３／分溶鋼トン以上、０．０４５　Ｎ■３／分溶鋼
トン以下とした。Ha3/min molten steel ton or more and 0.045 N3/min molten steel ton or less.

次に第２図に窒素ガス導入用ランスの浸漬深さを溶鋼深
さの５０％から９５％まで変化させたときの窒素添加歩
留（１）及び取鍋底部耐火物の溶損状況（２）の推移を
示す。なおこのときの窒素ガス流量は０．０４０　Ｎｍ
’　７分溶鋼トンである。Next, Figure 2 shows the nitrogen addition yield (1) and the state of erosion of the refractory at the bottom of the ladle (2) when the immersion depth of the nitrogen gas introduction lance was varied from 50% to 95% of the molten steel depth. ). Note that the nitrogen gas flow rate at this time was 0.040 Nm
' 7 minutes is a ton of molten steel.

第２図より明らかなように窒素添加歩留は窒素ガス導入
用ランスの浸漬深さが溶鋼深さの６０％以下では悪く８
５％までは浸漬深さに比例し増加するが、８５％を超え
ると窒素添加歩留は殆んど変化しない。一方、取鍋底部
耐火物は窒素ガス導入用ランスの浸漬深さの８５％以上
になると溶損が大きくなる。麩上の結果から窒素ガス導
入用ランスの浸漬深さは溶鋼深さの６０％以上８５％以
下とした。As is clear from Figure 2, the nitrogen addition yield is poor when the immersion depth of the nitrogen gas introduction lance is less than 60% of the molten steel depth.
Up to 5%, the nitrogen addition yield increases in proportion to the immersion depth, but beyond 85%, the nitrogen addition yield hardly changes. On the other hand, the refractory at the bottom of the ladle suffers from significant erosion when the depth of immersion exceeds 85% of the lance for introducing nitrogen gas. Based on the above results, the immersion depth of the nitrogen gas introduction lance was set to be 60% or more and 85% or less of the molten steel depth.

以下、本発明と従来法との比較を実施例により説明する
。Hereinafter, a comparison between the present invention and a conventional method will be explained using examples.

実施例１ ８Ｕ８５０４のステンレス鋼（１８，５％Ｏｒ　−８，
５％Ｎｉ）　５５　Ｔを溶製しＶＯＤ精錬する。上記溶
鋼（Ｎ　：　０．０１％）に対し、窒素ガス流量は０．
０４０　Ｎａ３／分溶鋼トン、窒素ガス導入用ランスの
浸漬深さは溶鋼深さの７５％の１．５ｍの添加条件で窒
素ガスを吹き込んだ。窒素ガス添加開始の温度は１６０
０〜１６２０ｔ：’で精錬後のスラグのＣａＯ／　５ｉ
ｏ２　は２．０〜２．２であり、窒素ガス添加完了迄の
１０分間で窒素含有量は０．０７％となり溶鋼温度は１
５７０Ｃで、生成された溶鋼の組成はＯＯ，０６％、８
ｉ　０．６％。Example 1 8U8504 stainless steel (18.5% Or -8,
5%Ni) 55T is melted and VOD refined. For the above molten steel (N: 0.01%), the nitrogen gas flow rate was 0.
Nitrogen gas was blown into the steel under the following conditions: 040 Na3/min molten steel tons, and the immersion depth of the nitrogen gas introducing lance was 1.5 m, which was 75% of the molten steel depth. The temperature at which nitrogen gas addition starts is 160
0~1620t: CaO/5i of slag after refining at '
o2 is 2.0 to 2.2, and in 10 minutes until the nitrogen gas addition is completed, the nitrogen content becomes 0.07% and the molten steel temperature decreases to 1.
At 570C, the composition of the molten steel produced is OO, 06%, 8
i 0.6%.

Ｍｎ１．２％、Ｏｒ　１８．５・％、Ｎｉ　８．５％、
ＮＯ６０７％、残部Ｆｅ　であった。次に第１表に従来
の窒化７エロクロ五忙よる窒素添加方法と本発明の各諸
元を比較表示する。Mn 1.2%, Or 18.5%, Ni 8.5%,
It was 607% NO and the balance was Fe. Next, Table 1 compares the specifications of the conventional nitrogen addition method using nitriding and the present invention.

第１表 上記第１表より明らかなように、本発明は従来法に比し
窒素添加歩留は大きく向上し、かつ安定した実績窒素値
を示し、コスト面でも従来法の４０％であグ大巾のコス
トダウンができた。Table 1 As is clear from Table 1 above, the present invention greatly improves the nitrogen addition yield compared to the conventional method, shows stable actual nitrogen values, and is 40% cheaper than the conventional method in terms of cost. We were able to reduce the cost of the large cloth.

窒素添加後の温度降下も本発明の方が従来法に比し少な
い。The temperature drop after nitrogen addition is also smaller in the present invention than in the conventional method.

実施例２ ２５％Ｏｒ　−７％Ｎｉ　−０，０２％Ｃの２相ステン
レス鋼で、目標窒素値０．１５％を狙って窒素添加した
ときの例について説明する◇ 上記溶鋼（Ｎ　：　０．Ｏ１％）Ｋ対し窒素ガス流量は
０．０４ＯＮＩ！１３／分溶鋼トン、窒素ガス導入用ラ
ンスの浸漬深さは溶鋼深さの７５％の１．５ｍの添加条
件で窒素ガスを吹込んだ。窒素ガス添加開始の温度は１
６４０Ｃで、精錬後のスラグのｃａｏ　／　５ｉｎ２　
は２．０〜２．２であり、窒素ガス添加完了までの２０
分間で窒素含有量は０．１５％となり、溶鋼温度は１５
７５Ｃで、生成された溶鋼の組成はＧ　Ｏ，０１０％、
Ｓｉ　０．４０％、Ｍｎ　００９％、Ｏｒ　２５．２％
、Ｎｉ　７％、Ｎ　Ｏｏｌ　５％、残部Ｆ６　であった
。Example 2 An example in which nitrogen is added to a 25% Or -7% Ni -0.02% C duplex stainless steel aiming at a target nitrogen value of 0.15% will be explained.◇ The above molten steel (N: 0.02%). Nitrogen gas flow rate is 0.04 ONI for O1%) K! Nitrogen gas was blown in at 13 tons of molten steel per minute, and the immersion depth of the nitrogen gas introduction lance was 1.5 m, which was 75% of the depth of the molten steel. The temperature at which nitrogen gas addition starts is 1
At 640C, slag cao/5in2 after refining
is 2.0 to 2.2, and it takes 20 to complete nitrogen gas addition.
The nitrogen content becomes 0.15% in 1 minute, and the molten steel temperature becomes 15%.
At 75C, the composition of the molten steel produced is GO,010%,
Si 0.40%, Mn 009%, Or 25.2%
, Ni 7%, N Ool 5%, and the balance F6.

以上の如（本発明は従来の窒素添加方法と異なり、即ち
ＶＯＤ精錬後、皆素源として従来の窒化合金に変え、大
気下で窒素ガスを導入することを特徴とし、窒素ガス添
加条件を窒素ガス流量で、溶鋼トン当り０，０５０　Ｎ
ｍ３／分以上、α０４５　Ｎｍ’　７分以下とし、窒素
ガス導入用ランスの浸漬深さを溶鋼深さの６０％以上、
８５％以下とするとと処より、従来方法に比し安定した
高い窒素添加歩留を得ることができ、大巾なコストダウ
ンに貢献で・きるなど大きな利点をもったものである０
　゛ なお、本発明の実施は上述実施例のステンレス鋼忙限る
ものでなく、他の鋼種にも適用できることは当然である
。As described above (the present invention is different from the conventional nitrogen addition method, that is, after VOD refining, the conventional nitride alloy is used as the element source, and nitrogen gas is introduced under the atmosphere, and the nitrogen gas addition conditions are changed to nitrogen Gas flow rate: 0,050 N per ton of molten steel
m3/min or more, α045 Nm' 7 minutes or less, and the immersion depth of the nitrogen gas introduction lance is at least 60% of the molten steel depth.
When the nitrogen addition rate is 85% or less, it is possible to obtain a stable and high nitrogen addition yield compared to conventional methods, which has great advantages such as contributing to a large cost reduction.
Note that the present invention is not limited to the stainless steel of the above-described embodiments, and can of course be applied to other types of steel.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は窒素ガス流量を変化させたときの窒素添加歩留
、溶鋼飛散状況及び取鍋側壁耐火物の溶損状況を示し、
第２図は窒素ガス導入用ランスの浸漬深さを変化させた
ときの窒素添加歩留及び取鍋底部耐火物の溶損状況を示
す。 オ／　ｌ］ 窒素６・ス＃Ｌ＋　（へ〇ワ２≦−身６−θロメ７）手
続補正書（方式） 昭和６０年６月／ど日 特許庁長官　志　賀　学　殿 り事件の表示　昭和５８年特許願第２４８６１９号２、
発明の名称　含窒素合金鋼の製造方法＆補正をする者、 事件との関係　特許出願人 住　所　東京都新宿区本塩町８番地の２名　称　日本ス
テンレス株式会社 ４、代理人 已補正の対象　図面 マ、補正の内容　別紙のとおシFigure 1 shows the nitrogen addition yield, molten steel scattering, and melting damage of the ladle side wall refractory when the nitrogen gas flow rate is changed.
Figure 2 shows the nitrogen addition yield and the state of erosion of the refractory at the bottom of the ladle when the immersion depth of the nitrogen gas introducing lance was varied. [O/l] Nitrogen 6・S#L+ (He〇wa 2≦-M6-θRome7) Procedural amendment (method) June 1985/Do Japan Commissioner of the Japan Patent Office Manabu Shiga Indication of Tonori case Showa 1958 Patent Application No. 248619 2,
Title of the invention Method for producing nitrogen-containing alloy steel & person making the amendment, relationship to the case Patent applicant address 8, Honshio-cho, Shinjuku-ku, Tokyo, 2nd name Nippon Stainless Co., Ltd. 4, subject of amendment by agent Drawings Contents of correction

Claims (1)

【特許請求の範囲】 含窒素合金鋼を製造するに際し、溶製した合金鋼をＶＯ
Ｄ精錬したる後窒素を添加する忙当り。 ノ＼゛。 窒素ガス導入用ランスな溶鋼内に浸漬深さを溶鋼深さの
６０％以上８５％以下となるように浸−潰し、窒素ガス
を０．０５０　Ｋｍ’　／分溶鋼トン以上、０．０４５
　Ｎｍ３７ｍ３調 入することを特徴とする含窒素合金鋼の製造方法。[Claims] When producing nitrogen-containing alloy steel, the melted alloy steel is VO
D: Adding nitrogen after refining.ノ＼゛. Immerse and crush the molten steel using a lance for introducing nitrogen gas so that the immersion depth is 60% or more and 85% or less of the molten steel depth, and add nitrogen gas at a rate of 0.050 Km'/min or more to 0.045 tons of molten steel.
A method for producing nitrogen-containing alloy steel, characterized in that 37 m3 of Nm is supplied.