JP3896709B2 - Method of melting high cleanliness steel - Google Patents
Method of melting high cleanliness steel Download PDFInfo
- Publication number
- JP3896709B2 JP3896709B2 JP30980598A JP30980598A JP3896709B2 JP 3896709 B2 JP3896709 B2 JP 3896709B2 JP 30980598 A JP30980598 A JP 30980598A JP 30980598 A JP30980598 A JP 30980598A JP 3896709 B2 JP3896709 B2 JP 3896709B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- cao
- inclusions
- high cleanliness
- mgo
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、高清浄度鋼の溶製方法に関し、とくに介在物量の低減と微細化に有効な転炉出鋼溶鋼の精製技術を提案する。
なお、本発明は、軸受材料やＳＣ材などとして用いられる高清浄度鋼の製造に適用される方法である。
【０００２】
【従来の技術】
軸受材料などに用いられる高清浄度鋼を溶製する方法としては、アーク加熱を行いながら長時間攪拌 (ＬＦ法) した後、真空脱ガス処理を行う方法や、特開昭57−73118 号公報に開示されているような、いわゆるＲＨ真空脱ガス処理を長時間行う方法などが知られている。しかし、これらの方法では、全酸素濃度の低下は達成されるものの、粗大な (＞10〜20μm)酸化物系介在物を含有していることから、例えば、軸受材料に適用される転動疲労寿命試験を行うと、必ずしもよい結果 (長寿命) が得られないという問題があった。
【０００３】
その他、高清浄度鋼を溶製する方法としては、特開平 1−222012号公報に開示されているような、溶鋼にCa−Siを添加して介在物の形態制御を行う方法や、特開平４−333359号公報に開示されているような、金属Mgを添加して介在物の形態制御を行う方法もある。しかし、これらの方法はCaやMgを合金や単体のまま添加しているため、CaやMgの濃度が局所的に高くなる部分があり、その部分ではCaＯやMgＯ濃度の高い粗大な介在物が不可避に生成し、これが前記転動疲労寿命を低下させる原因となっていた。
【０００４】
【発明が解決しようとする課題】
上述したように従来技術は、鋼中酸素濃度の低下には有効でも、軸受鋼の転動疲労寿命が向上しないとか、CaＯやMgＯ濃度が局部的に高く粗大な介在物の生成を阻止できないという課題を抱えていた。
そこで、本発明の目的は、従来技術が抱えている上述した課題を解決できる技術を提案すること、とくに鋼中介在物量が少なくかつ介在物粒径の小さい長疲労寿命の高清浄度鋼を製造するための溶製技術を提案することにある。
【０００５】
【課題を解決するための手段】
上掲の目的実現に向けた研究において、発明者らは、軸受鋼などの分野において必要とされる長疲労寿命特性を有する高清浄度鋼の溶製に当たっては、鋼中介在物量を低下させるとともに、粗大な介在物を減少させることが重要であるとの知見を得た。とくに、Al2O3 やこのAl2O3 を主成分としてCaＯやMgＯを含む粗大な介在物を減少させることが重要であることがわかった。
このような課題に対して本発明では、転炉から取鍋に出鋼した溶鋼に、MgＯ、CaＯ、Al2O3 を主成分とする混合フラックスを添加し、このことによってSiO2を１０wt％以下、MgＯを１５〜２５wt％、Al2O3 を３０〜４５wt％およびCaＯを３５〜５０wt％含有するスラグを調整し、このようなスラグを生成させた取鍋内溶鋼を不活性ガスによる攪拌処理を行い、その後ＲＨ脱ガス処理を行うようにしたことを特徴とする高清浄度鋼を溶製する方法を提案する。
【０００６】
【発明の実施の形態】
一般に、高清浄度鋼を溶製する場合、介在物の吸収能を増加させるために、スラグ中のCaＯ／Al2O3 を大きくすることが有効であると考えられてきた。しかし、発明者らの研究によれば、鋼中に残留する粗大な介在物というのは、多くはAl2O3 またはこのAl2O3 とともにCaＯやMgＯを含む介在物であり、これが軸受鋼などの転動疲労寿命を悪くする原因であり、そのような介在物を減少させることこそが高清浄度鋼を得るポイントであることがわかった。
また、この研究を通じ、CaＯを含む鋼中介在物におけるCaＯ濃度は、スラグ中CaＯ濃度に比べると非常に低く、それ故にスラグの巻き込みにより生成したものではないと推定された。また、スラグ中の組成と介在物形態の調査において、スラグ中のCaＯ濃度が高すぎる場合に限って、鋼中介在物の含有が認められることもわかった。こうした一連の実験結果により、発明者らは、粗大介在物を生成させることなく、疲労寿命特性に優れた高清浄度鋼を溶製するための最適スラグ組成を開発したのである。
【０００７】
さて、本発明の高清浄度鋼の溶製方法において、上述した所要の成分組成に調整されたスラグを有する溶鋼を不活性ガスで攪拌し、その後引き続きＲＨ真空脱ガス処理を行うと、精製溶鋼中には微細なMgＯ・Al2O3 系介在物を生成させることができ、所期した清浄度の高い溶鋼を得ることができる。
【０００８】
ここで、上記生成スラグ中のMgＯ濃度が低すぎると、介在物中にAl2O3 を生成し、その介在物の一部が粗大な介在物として存在するため、寿命の低下を引き起こす。また、MgＯの濃度が高すぎる場合、スラグ中に固相部分が多くなり、フラックスが有効利用されないばかりでなく、介在物の吸収能が減少し清浄性の悪化、寿命の低下を引き起こす。一方、SiO2濃度が高すぎる場合も、SiO2による再酸化で溶鋼の清浄性が低下し、また、CaＯ濃度が高すぎる場合には、Al2O3 −CaＯ系の粗大な介在物を生成することとなる。
従って、清浄性が高く粗大な介在物が存在しない高清浄度鋼の製造というのは、CaＯ、MgＯ、SiO2濃度をともに規制したスラグを用いて溶製することが必要である。
【０００９】
【実施例】
本発明の実施例を説明する。ここでは、Ｃ＝0.98〜1.03wt％、Si＝0.2 〜0.3 wt％、Cr＝1.3 〜1.6 wt％、Al＝0.02〜0.05wt％の転炉出鋼後の溶鋼 180〜200 ｔ用いて実験を行った。その結果を比較例とともに表１に示す。
実施例では、上記溶鋼を転炉から取鍋に出鋼した後、フラックスを 2.5〜3.0 ｔ添加した。このフラックスの組成は、CaＯを30〜40wt％、Al2O3 を40〜50wt％、MgＯを15〜30wt％含むものを用いた。上記フラックスを添加しスラグを生成させるための溶鋼の攪拌には、Arガス流量3 〜3.5 Nm3/min で４〜８分処理し、その後ＲＨ真空脱ガス装置で30分間処理を行った。実施例のスラグ組成は表１に示すとおり、SiO2＝７〜９wt％、MgＯ＝15〜21wt％、CaＯ＝36〜49wt％であった。
【００１０】
比較例では、添加フラックスとして、CaＯを40wt％、Al2O3 を40wt％、MgＯを20wt％含むものを1.5 t 添加し、スラグ生成後のSiO2濃度が12wt％と高かったもの (比較例１) 、CaＯが60wt％、Al2O3 が40wt％のスラグを3t添加し、MgＯ濃度が低かった場合 (比較例２) である。
一方、実施例においては、溶鋼中全酸素量は4 〜6 ppm と低く、かつ介在物粒径を測定したところ、320 mm2 あたりの最大径は、全て10μm 以下であった。一方、比較例１では、SiO2濃度が高かったため、全酸素量が12ppm と高くなった。また、320 mm2 あたりの最大介在物粒径も12.5μm と大きかった。また、比較例２においては、全酸素量は６ppm と低かったが、最大介在物径は15μm と大きかった。この介在物はCaＯを含有していることが確認された。
このように、各実施例の方法を用いることにより、全酸素量が低く、最大介在物粒径が小さな高清浄度鋼が溶製できることが確かめられた。
【００１１】
【表１】
【発明の効果】
以上説明したように本発明によれば、介在物量が少なくかつ介在物粒径の小さな高清浄度鋼の溶製が可能となった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for melting high cleanliness steel, and in particular, proposes a refinement technique for molten steel from a converter that is effective in reducing the amount of inclusions and making it finer.
In addition, this invention is a method applied to manufacture of the high cleanliness steel used as a bearing material, SC material, etc.
[0002]
[Prior art]
As a method of melting high cleanliness steel used for bearing materials, etc., a method of performing a vacuum degassing treatment after stirring for a long time (LF method) while performing arc heating, or JP-A-57-73118 And a method of performing a so-called RH vacuum degassing process for a long time as disclosed in Japanese Patent Application No. 2004-259867. However, although these methods achieve a reduction in total oxygen concentration, they contain coarse (> 10 to 20 μm) oxide inclusions, so that, for example, rolling fatigue applied to bearing materials When a life test is performed, there is a problem that a good result (long life) cannot always be obtained.
[0003]
Other methods for melting high cleanliness steel include a method for controlling the form of inclusions by adding Ca-Si to molten steel, as disclosed in JP-A-1-222012, There is also a method for controlling the form of inclusions by adding metal Mg as disclosed in Japanese Patent No. 4-333359. However, since these methods add Ca or Mg as an alloy or simple substance, there is a portion where the concentration of Ca and Mg is locally increased, and in that portion there are coarse inclusions with high CaO and MgO concentrations. It was inevitably generated, and this was a cause of lowering the rolling fatigue life.
[0004]
[Problems to be solved by the invention]
As described above, the conventional technology is effective for lowering the oxygen concentration in the steel, but does not improve the rolling fatigue life of the bearing steel, or cannot prevent the formation of coarse inclusions with locally high CaO and MgO concentrations. I had a problem.
Therefore, the object of the present invention is to propose a technique that can solve the above-mentioned problems of the prior art, and in particular, to produce a high cleanliness steel with a long fatigue life with a small amount of inclusions and a small inclusion particle size. The purpose is to propose a melting technique for this purpose.
[0005]
[Means for Solving the Problems]
In the research for realizing the above-mentioned purpose, the inventors reduced the amount of inclusions in the steel in melting high cleanliness steel having long fatigue life characteristics required in the field of bearing steel and the like. It was found that it is important to reduce coarse inclusions. In particular, it has been found that it is important to reduce coarse inclusions containing Al 2 O 3 or this Al 2 O 3 as a main component and containing CaO and MgO.
In the present invention In order to solve such a problem, the molten steel was tapped to a ladle from a converter furnace, adding MgO, CaO, a flux mixture composed mainly of Al 2 O 3, a SiO 2 10 wt% by this hereinafter, MgO and 15-25 wt%, the 30～45Wt% and CaO of Al 2 O 3 by adjusting the slag containing 35-50 wt%, stirring the ladle of molten steel that generated such slags with inert gas We propose a method of melting high cleanliness steel characterized in that the treatment is followed by RH degassing.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In general, when melting high cleanliness steel, it has been considered effective to increase CaO / Al 2 O 3 in the slag in order to increase the absorption capacity of inclusions. However, according to the researches of the inventors, the coarse inclusions remaining in the steel are mostly inclusions containing Al 2 O 3 or this Al 2 O 3 together with CaO and MgO, which is a bearing steel. It has been found that reducing the number of such inclusions is the key to obtaining high cleanliness steel.
Also, through this study, it was estimated that the CaO concentration in inclusions in steel containing CaO was very low compared to the CaO concentration in slag, and therefore was not generated by slag entrainment. Further, in the investigation of the composition and inclusion form in the slag, it was also found that inclusion of inclusions in the steel was recognized only when the CaO concentration in the slag was too high. Based on such a series of experimental results, the inventors have developed an optimum slag composition for melting high cleanliness steel having excellent fatigue life characteristics without generating coarse inclusions.
[0007]
Now, in the method for melting high cleanliness steel of the present invention, when the molten steel having the slag adjusted to the required component composition described above is stirred with an inert gas and then subjected to RH vacuum degassing treatment, refined molten steel is obtained. Fine MgO · Al 2 O 3 inclusions can be generated in the inside, and a desired high clean steel can be obtained.
[0008]
Here, if the MgO concentration in the generated slag is too low, Al 2 O 3 is generated in the inclusions, and some of the inclusions are present as coarse inclusions, leading to a reduction in life. On the other hand, if the MgO concentration is too high, the solid phase portion increases in the slag, and not only the flux is not effectively used, but also the inclusion absorption capacity is reduced, leading to deterioration in cleanliness and life. On the other hand, even when the SiO 2 concentration is too high, the cleanliness of the molten steel decreases due to re-oxidation with SiO 2 , and when the CaO concentration is too high, coarse inclusions of Al 2 O 3 —CaO are generated. Will be.
Therefore, the production of a high cleanliness steel having high cleanliness and no coarse inclusions requires melting using slag that regulates the CaO, MgO, and SiO 2 concentrations.
[0009]
【Example】
Examples of the present invention will be described. Here, an experiment was conducted using 180 to 200 t of molten steel after the converter steel with C = 0.98 to 1.03 wt%, Si = 0.2 to 0.3 wt%, Cr = 1.3 to 1.6 wt%, and Al = 0.02 to 0.05 wt%. went. The results are shown in Table 1 together with comparative examples.
In the examples, after the molten steel was discharged from the converter into a ladle, 2.5 to 3.0 t of flux was added. The composition of the flux, 30~40wt% of CaO, 40~50wt% of Al 2 O 3, was used containing MgO 15 to 30 wt%. For stirring the molten steel to add the above flux to generate slag, treatment was performed at an Ar gas flow rate of 3 to 3.5 Nm 3 / min for 4 to 8 minutes, followed by treatment with an RH vacuum degasser for 30 minutes. As shown in Table 1, the slag composition of the examples was SiO 2 = 7-9 wt%, MgO = 15-21 wt%, CaO = 36-49 wt%.
[0010]
In the comparative example, an additive flux containing 40 wt% CaO, 40 wt% Al 2 O 3 and 20 wt% MgO was added for 1.5 t, and the SiO 2 concentration after slag generation was as high as 12 wt% (Comparative Example) 1), CaO is 60 wt%, Al 2 O 3 is added 3t of 40 wt% of the slag, it is when the MgO concentration was low (Comparative example 2).
On the other hand, in the examples, the total oxygen content in the molten steel was as low as 4 to 6 ppm, and when the inclusion particle size was measured, the maximum diameter per 320 mm 2 was all 10 μm or less. On the other hand, in Comparative Example 1, since the SiO 2 concentration was high, the total oxygen amount was as high as 12 ppm. The maximum inclusion particle size per 320 mm 2 was also large at 12.5 μm. In Comparative Example 2, the total oxygen content was as low as 6 ppm, but the maximum inclusion diameter was as large as 15 μm. This inclusion was confirmed to contain CaO.
Thus, it was confirmed that by using the method of each example, a high cleanliness steel having a low total oxygen content and a small maximum inclusion particle size can be melted.
[0011]
[Table 1]
【The invention's effect】
As described above, according to the present invention, it is possible to melt high cleanliness steel with a small amount of inclusions and a small particle size of inclusions.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30980598A JP3896709B2 (en) | 1998-10-30 | 1998-10-30 | Method of melting high cleanliness steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30980598A JP3896709B2 (en) | 1998-10-30 | 1998-10-30 | Method of melting high cleanliness steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000129336A JP2000129336A (en) | 2000-05-09 |
| JP3896709B2 true JP3896709B2 (en) | 2007-03-22 |
Family
ID=17997467
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30980598A Expired - Fee Related JP3896709B2 (en) | 1998-10-30 | 1998-10-30 | Method of melting high cleanliness steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3896709B2 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4499969B2 (en) * | 2001-11-15 | 2010-07-14 | Ｊｆｅスチール株式会社 | Desulfurization method by ladle refining of molten steel |
| KR100711410B1 (en) * | 2004-12-09 | 2007-04-30 | 가부시키가이샤 고베 세이코쇼 | Highly Ductile Steel Sheet and Method of Manufacturing the Same |
| KR100723302B1 (en) | 2006-10-25 | 2007-05-31 | 지엠티 엔 티 주식회사 | Tundish and ladle flux for the basic liner system |
| JP4641022B2 (en) * | 2006-11-28 | 2011-03-02 | 株式会社神戸製鋼所 | Manufacturing method of high cleanliness steel |
| KR20090101407A (en) * | 2006-12-22 | 2009-09-28 | 요시자와 셋카이 고교 가부시키가이샤 | Flux for refining steel of low nitrogen, low oxygen and low sulfur |
| JP4257368B2 (en) * | 2007-06-05 | 2009-04-22 | 株式会社神戸製鋼所 | Manufacturing method of high cleanliness steel |
| KR101009895B1 (en) | 2008-07-25 | 2011-01-20 | 현대제철 주식회사 | Method for preventing slag over flow of vacuum refining process |
| FR2938530B1 (en) * | 2008-11-19 | 2011-07-29 | Kerneos | POROUS MAGNESIAN CLINKER, METHOD OF MANUFACTURE AND USE AS FLOW FOR PROCESSING STEEL DAIRY |
| JP5387045B2 (en) * | 2009-02-25 | 2014-01-15 | Ｊｆｅスチール株式会社 | Manufacturing method of bearing steel |
| JP5333536B2 (en) * | 2011-07-22 | 2013-11-06 | 新日鐵住金株式会社 | High cleanliness bearing steel and its melting method |
| CN102876851B (en) * | 2012-10-08 | 2014-10-15 | 武汉钢铁(集团)公司 | Method for improving calcium yield of RH vacuum furnace |
| CN108463564A (en) * | 2016-12-15 | 2018-08-28 | 拓莱技术株式会社 | Fuel feed system |
| CN109702158B (en) * | 2019-01-21 | 2020-12-29 | 湖南工业大学 | Casting powder for high-aluminum steel continuous casting and preparation method and application thereof |
-
1998
- 1998-10-30 JP JP30980598A patent/JP3896709B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000129336A (en) | 2000-05-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101364472B1 (en) | Grain refiners for steel-Manufacturing methods and use | |
| JP3896709B2 (en) | Method of melting high cleanliness steel | |
| JP5170975B2 (en) | Manufacturing method of iron-based amorphous material | |
| JP6237343B2 (en) | Melting method of high clean steel | |
| TW202138588A (en) | Stainless steel for metal foil, stainless steel foil, and method for manufacturing the same | |
| JP5541310B2 (en) | Manufacturing method of highly clean steel | |
| JP2004277777A (en) | Steel with finely dispersed inclusion superior in fatigue life | |
| WO2017043091A1 (en) | Method for producing alloyed steel powder for sintered member starting material | |
| JP5047477B2 (en) | Secondary refining method for high Al steel | |
| JP2004169147A (en) | Refining process for clean steel containing extremely low amount of non-metallic inclusion | |
| JP2010144195A (en) | Method for manufacturing high nitrogen-containing stainless steel | |
| CN116287550A (en) | Method for improving morphology of B-type inclusion in bearing steel by adding rare earth alloy | |
| JP5590056B2 (en) | Manufacturing method of highly clean steel | |
| JP4111352B2 (en) | High-cleaning refining method for stainless steel | |
| JP2018127680A (en) | Method for smelting clean steel | |
| JP3036362B2 (en) | Manufacturing method of oxide dispersion steel | |
| JP3893785B2 (en) | Melting method of high carbon steel for wire | |
| JP6627536B2 (en) | Steel with excellent toughness in weld heat affected zone and method of manufacturing steel with excellent toughness in weld heat affected zone | |
| JP2008266706A (en) | Method for continuously casting ferritic stainless steel slab | |
| JP2004346402A (en) | Method of refining steel material for spring | |
| JP4726448B2 (en) | Method for producing spheroidal graphite cast iron | |
| JP4418119B2 (en) | Method for dispersing fine oxides in molten steel | |
| RU2715513C1 (en) | Method of producing cast composite material based on copper | |
| JP4227478B2 (en) | Low carbon steel slab manufacturing method | |
| JP3225788B2 (en) | Method for producing steel with excellent toughness in weld heat affected zone |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20050825 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20061116 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20061128 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20061211 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110105 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120105 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130105 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130105 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140105 Year of fee payment: 7 |
|
| LAPS | Cancellation because of no payment of annual fees |