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31. 发明专利

JPH1150127A REFINING OF LOW SILICON STAINLESS STEEL 失效
公开(公告)号：JPH1150127A
公开(公告)日：1999-02-23
申请号：JP21545597
申请日：1997-07-28
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , MAKINO NOBUYUKI , MORISHIGE HIROAKI , HATA KOKI
IPC分类号： C21C7/00
摘要： PROBLEM TO BE SOLVED: To execute a stable casting and to reduce the developing rate of defect caused by inclusion in a product production process and the product by controlling the composition and the quantity of the inclusion in a steel, in the production process of a low Si stainless steel containing

32. 发明专利

JPH0885813A METHOD FOR EFFECTIVELY REFINING MOLTEN CHROMIUM-CONTAINING STEEL USING DECARBURIZED SLAG 失效
公开(公告)号：JPH0885813A
公开(公告)日：1996-04-02
申请号：JP22222894
申请日：1994-09-16
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , TANAKA SHIGENORI , OKIMORI MAYUMI , IWASAKI HIROSHI , MORISHIGE HIROAKI
IPC分类号： C21C7/00 , C21C5/28 , C21C7/068
摘要： PURPOSE: To reduce and recover produced chromium oxide in a method at a low cost in a decarburization-refining of molten chromium-containing steel and also, to effectively execute the reduction and the decarburization. CONSTITUTION: At the time of tapping the decarburization-refined molten steel in the decarburization-refining of the molten chromium-containing steel, the crude molten steel having >=1400 deg.C, >=0.2mass% [Si] concn. and >=1.2mass% [C] concn., is received under the condition of remaining slag containing 15-50mass% chromium oxide produced by the decarburization-refining in a furnace. The chromium oxide is reduced with [Si] and [C] in the crude molten steel. By this method, since the remarkable lowerings of the unit consumptions of Si for reduction and dilute gas, and the shortening of the refining time are obtd., the refining cost can remarkably be reduced.

33. 发明专利

JPH0885810A METHOD FOR REFINING MOLTEN CHROMIUM-CONTAINING STEEL 失效
公开(公告)号：JPH0885810A
公开(公告)日：1996-04-02
申请号：JP22538094
申请日：1994-09-20
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , TANAKA SHIGENORI , OKIMORI MAYUMI , IWASAKI HIROSHI , MORISHIGE HIROAKI
IPC分类号： C21C7/00 , C21C7/068 , C21C7/10
摘要： PURPOSE: To easily control [N] concn. while using inexpensive N2 gas by using the same refining vessel after executing decarburizing treatment to molten chromium-containing steel under the atmospheric pressure, blowing N2 gas of a specific quantity and executing reduction treatment under a specific vacuum degree. CONSTITUTION: After executing the decarburizing treatment to the molten chromium-containing steel under the atmospheric pressure by using the same refining vessel, the decarburizing and reduction treatment or only the reduction treatment is executed under the vacuum. At this time, the N2 gas or the N2 +Ar gas as blowing gas in the reduction treatment is blown at >=0.2Nm /min.ton of molten steel. At the same time, the reduction treatment is executed for at least one min in the vacuum degree satisfying the equation a=-1.35- 3280/(T+273)-0.75} (0.01[Ni]-0.045[Cr]+0.009), P ×10 )+10 or P ×10 )× (QAr +QN2 )/QAr }+10 matching to [N] concn. Wherein, T is molten steel temp. ( deg.C), [Ni] and [Cr] are Ni and Cr (concn.%) in the molten steel, P is the vacuum degree (Torr), and QAr and QN2 are Ar and N2 gas blowing quantity, respectively (Nm /min).

34. 发明专利

JPH07331322A METHOD FOR DECARBURIZATION-REFINING CHROMIUM-CONTAINING MOLTEN STEEL 失效
公开(公告)号：JPH07331322A
公开(公告)日：1995-12-19
申请号：JP12158694
申请日：1994-06-02
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , TANAKA SHIGENORI , MORISHIGE HIROAKI , IWASAKI HIROSHI , OKIMORI MAYUMI
IPC分类号： C21C7/00 , C21C7/068 , C21C7/072
摘要： PURPOSE:To efficiently decarburize by suppressing [Cr] oxidation in molten steel and consumption of inert gas to the utmost and thus to reduce a refining cost. CONSTITUTION:In a decarburization-refining method in which gaseous oxygen or a mixture of gaseous oxygen and inert gas is blown from above or below a bath surface of a Cr-containing molten steel, gaseous CO2 is mixed to the above-mentioned gas as a blowing gas. Decomposition rate of gaseous CO2 is determined by (1) to (4) formulas. The gaseous mixture mixed with the gaseous CO2 is blown in so that the decomposition rate attains 0, R=R'... (2). R'=-120log [[C]/P ]-40... (3). P=1.4Q02/(1.4Q02+Qd)... (4). [C]:[C] concentration (mass %) in molten steel. Q02: flow rate (Nm /Hr) of gaseous oxygen without admixture of gaseous CO2. Qd: flow rate (Nm /Hr) of inactive gas without admixture of gaseous CO2.

35. 发明专利

JPH04276009A DECARBONIZED REFINING METHOD FOR CHROMIUM-CONTAINING MOLTEN STEEL 失效
公开(公告)号：JPH04276009A
公开(公告)日：1992-10-01
申请号：JP3729791
申请日：1991-03-04
申请人： NIPPON STEEL CORP
发明人： NAKAO RYUJI , TANAKA SHIGENORI , MORISHIGE HIROAKI , TAKANO HIRONORI , TSUJINO RYOJI , HIRATA HIROSHI
IPC分类号： C21C7/00 , C21C7/068
摘要： PURPOSE:To restrain the oxidation of chromium and to efficiently execute decarbonization of a chromium-containing molten steel. CONSTITUTION:Gaseous oxygen is blown from the bottom of a bath surface and above the bath surface of the chromium-incorporating molten steel containing >=0.3% C concn. and also decarbonization is executed in the condition of satisfying the following inequality to a slag quantity at firing point of the gaseous oxygen. (21.39%X[wt.% Si]+WS+WF)/L/L0)

36. 发明专利

JPH0260723B2 失效
公开(公告)号：JPH0260723B2
公开(公告)日：1990-12-18
申请号：JP21207582
申请日：1982-12-04
申请人： NIPPON STEEL CORP
发明人： IKEHARA YASUMASA , ARYOSHI HARUKI , MORISHIGE HIROAKI
IPC分类号： C21C7/00 , C21C7/068 , C21C7/072

37. 发明专利

JPS62139807A PRODUCTION OF HIGH-PURITY STAINLESS STEEL 失效
公开(公告)号：JPS62139807A
公开(公告)日：1987-06-23
申请号：JP28104585
申请日：1985-12-16
申请人： NIPPON STEEL CORP
发明人： IKEHARA YASUMASA , ARIYOSHI HARUKI , MORISHIGE HIROAKI
IPC分类号： C21C7/00 , C21C5/00 , C21C7/04 , C21C7/068
摘要： PURPOSE:To produce a high-purity stainless steel contg. P and S at low ratios by refining a molten metal in a reaction vessel which can make oxygen blowing and stirring by using a low-phosphorus molten iron and Cr ore as a raw material and low-phosphorus lime as a fluxing agent and using a reducing agent essentially consisting of Al. CONSTITUTION:The low-phosphorus molten iron carburized by about 4% with graphite carbon is charged into a refining furnace such as AOD. O2 and Ar are blown from the bottom tuyeres into the furnace to oxidize and remove the C contained therein and to increase the temp. of the molten metal. The Cr ore and the low-phosphorus line which is a slag forming agent are added from the furnace top to the molten metal when the prescribed temp. is attained. The Cr ore and Al scrap contg. Ti scrap and Si scrap are charged as a reducing agent to the molten metal, by which Cr2O3 and FeO in the Cr ore are reduced and the CaO/Al2O3 in the molten slag is made 1-1.7. The molten slag is discharged and again the Cr ore and quick lime are added to the molten metal. the molten metal is then desiliconized by stirring the same by the gaseous Ar blown thereto. The high-purity ferritic stainless steel contg. P and S at low ratios and having an excellent weld crack resistant characteristic and stress corrosion resistant characteristic is produced. An austenitic stainless steel is obtd. if Ni is added to the raw material.

38. 发明专利

JPS61174306A NON-TILTING FURNACE OPERATING METHOD IN REFINING OF CHROMIUN STEEL 失效
公开(公告)号：JPS61174306A
公开(公告)日：1986-08-06
申请号：JP1501185
申请日：1985-01-29
申请人： NIPPON STEEL CORP
发明人： ARIYOSHI HARUKI , HIDAKA RYOICHI , MORISHIGE HIROAKI
IPC分类号： C21C5/28 , C21C7/00 , C21C7/068
摘要： PURPOSE:To detect quickly the [C] in the steel during refining of a Cr steel by changing over a mixed gas ratio in accordance with the predicted [C] while the [C] in the steel is in a prescribed range and determining the timing for changing over the next mixed gas ratio in accordance with the simultaneous analysis value of the C and S during blowing. CONSTITUTION:The mixed gas ratio is changed over in accordance with the predicted [C] while the [C] in the steel is between 0.7-0.05% in the decarburization refining stage of the molten Cr steel by an AOD furnace. The timing for the next change over of the mixed gas ratio is determined in accordance with the component analysis values obtd. by using a pin sampler during blowing and a simultaneous analyzer for [C] and [S]. More specifically, the temp. is measured and the sample is drawn by the pin sampler with the non-tilted furnace without interruption the supply of the gaseous O2 from the inside pipe of double tuyeres and the diluting gas at the predicted [C] value in the steel=0.25%. The ratio is immediately changed over to the O2 in the inside pipe/the diluting gas (Ar) ratio=1/2 and the refining is continued. The intendended change over to O2/Ar ratio=1/3 is made possible at the [C] value=0.12% in about 2min after the analysis values are known even if the actual [C] value is as low as 0.19% with respect to, for example, the predicted [C] value=0.25%.

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