Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
  • C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1261—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest following hot rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1272—Final recrystallisation annealing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1277—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
  • C21D8/1283—Application of a separating or insulating coating

Definitions

• the melt material is cast into ingots or slabs, reheated, hot rolled to hot band, annealed, pickled, cold reduced to final gauge, subjected to a decarburizing step and given a final high temperature anneal to produce the desired final orientation.
• the temperature of the anneal following hot rolling bears an inverse relationship to the final gauge of the silicon steel.
• the silicon steel Prior to the final anneal the silicon steel is provided with an annealing separator.
• a grain growth inhibitor may be provided in the environment of the stock during the primary grain growth stage of the final anneal so as to inhibit primary grain growth and to favor the growth of cube-on-edge oriented nuclei during the secondary grain growth stage.
• Silicon steels having the cube-on-edge grain orientation were first produced by Goss, as taught in U.S. Pat. No. 1,965,559. From the outset, however, silicon steels of this orientation with consistently good magnetic properties were difficult to produce on a commercial basis. Aa a consequence, prior art workers have devoted much time and effort to the development of such silicon steels.
• sulfur or a sulfur compound which dissociates or decomposes at the temperatures of primary grain growth may be added to the annealing separator.
• the annealing atmosphere may be charged with hydrogen sulfide or any other appropriate gaseous sulfur compound.
• hydrogen sulfide or any other appropriate gaseous sulfur compound may be added to the atmosphere in the decarburizing step ahead of the final anneal. The sulfur compound reacts with the iron surface to form a controlled iron sulfide film on the material, providing a source of sulfur during the primary grain growth stage of the final anneal.
• the melt composition is critical and must include from 0.025 to 0.085 percent carbon, from 2.5 to 4.0 percent silicon, from 0.005 to 0.050 sulfur and, of special importance, from 0.010 to 0.065 percent acidsoluble aluminum, the balance being iron and mixed impurities.
• the silicon steel is reduced to final gauge by one or more stages of cold rolling.
• the last stage of cold rolling produces a reduction of 81 to percent and that before the final cold rolling step the silicon iron be subjected to a high temperature anneal such that aluminum nitrides are formed in the steel sheet in such quantity that more than 0.0020 percent nitrogen stage of cold rolling be a high temperature anneal followed by a relatively rapid cool or quench.
• a high temperature anneal such that aluminum nitrides are formed in the steel sheet in such quantity that more than 0.0020 percent nitrogen stage of cold rolling be a high temperature anneal followed by a relatively rapid cool or quench.
• United States Letters Pat. No. 3,700,506 teaches the use of a particular annealing separator in the process of the above mentioned U.S. Pat. No. 3,287,183.
• a magnesium oxide separator is used to which a titanium compound and a maganese compound have been added.
• boron or a boron compound is additionally added together with sulfur or a sulfur compound or selenium or a selenium compound.
• the patent teaches that the boron or boron compound when added with sulfur or selenium results in an improved core loss in the final product and in the formation of a thin, uniform glassy film on the silicon steel.
• the boron or boron compound is used to control secondary grain growth during the final anneal, the aluminum nitrides being relied upon to control grain growth during theprimary grain growth stage of the final anneal.
• No unusually high temperature anneal is required prior to the final anneal; pickling may be readily accomplished in the usual manner; boron and nitrogen additions are made to control grain growth during the primary grain growth stage of the final anneal; and a conventional insulative mill glass may be formed on the silicon steel as a part of its regular processing.
• the present invention contemplates the addition of boron and nitrogen in critical amounts to a conventional melt composition for cube-on'edge oriented silicon iron.
• the melt may also contain up to 0.008 aluminum.
• melt process can be either cast as ingots or continuously cast slabs.
• the silicon steel Prior to hot rolling, the silicon steel is heated to a temperature of from about 2,300 to about 2,550 and thereafter hot rolled to hot band. Following hot rolling, the silicon steel is annealed within a temperature range of from about 1,500F to about 2100F and the annealing temperature used bears an inverse relationship to the final gauge of the silicon steel. The anneal is followed by conventional pickling and cold rolling to final gauge in one or more stages.
• the cold rolled material is conventionally decarburized and coated with a magnesia (MgO) annealing separator.
• MgO magnesia
• an inhibitor may be provided in the environment of the silicon iron during the primary grain growth stage of the final anneal.
• from about 1 percent to about 6 percent by weight of sulfur may be added to the magnesia annealing separator
• the decarburized and coated material is then subjected to a final anneal in a dry hydrogen atmosphere at a temperature of from about 2,000F to about 2,300F.
• the heat-up portion of the final anneal may be conducted in a nitrogen atmosphere, the temperature being raised at the rate of less than about F per hour and preferably about 50F per hour.
• the cube-on-edge oriented silicon iron of the present invention is characterized by a permeability greater than about 1,820 and up to 1,900 or beyond.
• the melt contemplated by the present invention may be produced by any suitable and known method such as by an openhearth furnace, a converter, an electric furnace, a vacuum melting furnace or the like.
• the initial melt composition is conventional for the production of cube-on-edge oriented silicon iron with respect to silicon, maganese, carbon and sulfur.
• critical amounts of boron and nitrogen are added.
• the melt composition may be stated in weight percent as follows: from about 2 percent to about 4 percent silicon, from about 0.01% to about 0.15 percent (and preferably from about 0.03 percent to about 0.15 percent) manganese, from about 0.02 percent to about 0.05 percent carbon, from about 0.01 percent to about 0.03 percent sulfur, from about 0.002 percent to about .012% (and preferably from about 0.003 percent to about 0.010 percent) boron, from about 0.003 percent to about 0.010 percent (and preferably from about 0.004 percent to about 0.008percent) nitrogen, the balance being iron and those impurities incident to the mode of manufacture.
• aluminum may be present in the above stated melt composition (as a deoxidizer or impurity) in an amount up to about 0.008 percent.
• the optimum amount of boron is believed to be 0.007 percent and the optimum amount of nitrogen is believed to be 0.007 percent.
• the boron content of the initial melt can be achieved in any suitable and well known manner, including the addition to the initial melt of a boron-containing compound such as ferroboron.
• the nitrogen content of the initial melt can similarly be achieved by any suitable and well known means.
• nitrogen may be added in the form of a nitrogen compound such as nitrided manganese. Nitrogen may also be added by blowing.
• the desired nitrogen content may be provided through the use of a melting process which normally results in an appropriate nitrogen content, as for example the use of the electric furnace to produce a low carbon melt.
• the silicon melt may be cast either as ingots or continuously cast slabs. 1f the steel is cast into ingots, the ingots can be either directly hot rolled to hot band, or alternatively, they can be rolled to slabs of intermediate thickness, which slabs are subsequently reheated and hot rolled to hot band.
• the slabs should be reheated prior to hot rolling to a temperature in the range of from about 2,400F to 2,550F (and preferably about 2,500F) in accordance with the above mentioned U.S. Pat. No. 2,599,340.
• the final hot band will normally have a thickness of from about 0.050 to about 0.10 inch.
• the silicon steel is annealed at a temperature of from about 1,500F to about 2,100F, and preferably from about 1,700F to about 2,000F for about 3 /2 minutes in any appropriate atmosphere such as air, products of combustion, etc. It has been determined that to obtain optimum permeability values the temperature of this anneal bears an inverse relationship to the desired final thickness of the silicon steel. Thus, when thinner final sheet stock is to be produced, the temperature of this anneal should fall within the upper portions of the above stated ranges. Similarly, when thicker sheet stock is to be produced, the temperature of this anneal should fall within the lower portion of the above stated ranges.
• the annealed, hot rolled silicon steel may be spray quenched or air cooled. The silicon steel is thereafter conventionally pickled and cold reduced in a single stage (or in two or more stages with intermediate anneals) to final gauge.
• the cold reduced silicon steel is decarburized in a wet hydrogen atmosphere at a temperature of about 1,500F and a dewpoint of about 135, in accordance with the above mentioned U.S. Pat. No. 2,287,467.
• the silicon steel is provided with an appropriate annealing separator such as magnesia, alumina, calcium oxide or mixture of these.
• an appropriate annealing separator such as magnesia, alumina, calcium oxide or mixture of these.
• magnesia annealing separator can be used in accordance with the above noted U.S. Pat. No. 2,906,645.
• the magnesia separator may be applied to the silicon steel in any of the conventional and well known ways.
• the silicon steel having been provided with an annealing separator, is subjected to a final box anneal at a temperature of from about 2,000F to about 2,300F, and preferably about 2,200F for a period of time of from about 8 to about hours.
• This anneal designated herein as the final anneal for purposes of clarity, is that anneal during the secondary grain growth stage of which the cube-on-edge orientation is achieved.
• the anneal is conducted in a dry hydrogen atmosphere.
• a nitrogen atmosphere should be used during the heat-up portion of the an neal, dry hydrogen being substituted therefore during the remainder of the annealing treatment.
• the heat-up portion of the anneal should have a relatively slow temperature rise of less than about 125F per hour and preferably about 50 per hour.
• the material was cast into 1 inch thick ingots. The ingots were heated to l,900F and hot rolled to approximately 0.09 in. First and second samples of this material were annealed at 1,700F for 3 /2 minutes. A third sample was annealed at 2,100F for 3 /2 minutes. The first sample was air cooled and cold rolled to 14 mils. The second and third samples were each spray quenched and cold rolled to 10 mils.
• the material was cast into 1 inch thick ingots, heated to 1,900F and hot rolled to approximately 0.09 inches.
• the material was annealed at 1,700F for 3% minutes, air cooled, pickled and cold rolled to a thickness of 14 mils.
• the cold rolled silicon steel was decarburized at 1,500F in wet hydrogen at a dewpoint of 135 and was coated with a magnesia separator containing 6 percent by weight of sulfur.
• the coated silicon steel was given a final anneal at 2,200F for 27 hours with a heat-up rate of 50 per hour. During the heat-up portion of the final anneal a nitrogen atmosphere was used, a hydrogen atmosphere being used throughout the remainder of the anneal.
• a method of making cube-on-edge oriented silicon steel comprising the steps of preparing a silicon steel melt having a composition in weight percent consisting essentially of from about 2 to about 4 percent silicon, from about .01 to about 0.15 percent manganese, from about 0.02 to about 0.05 percent carbon, from about 0.01 to about 0.03 percent sulfur, from about 0.003 to about 0.010 percent boron, from about 0.003 to about 0.010 percent nitrogen, up to 0.008 percent aluminum, the balance being iron and impurities incident to the mode of manufacture, casting said silicon steel melt, reheating said silicon steel at a temperature of from about 2,300F to about 2,550F, hot rolling said silicon steel to an intermediate thickness of from about 0.050 to about 0.100 in., annealing said hot rolled silicon steel at a temperature of from about 1,500F to about 2,100F, pickling said annealed silicon steel and cold reducing it to final gauge, decarburizing said cold reduced silicon steel, providing an annealing separator for said decarburized
• melt composition in percent by weight consists essentially of from about 2 to about 4 percent silicon, from about 0.03 to about 0.15 percent manganese, from about 0.02 to about 0.05 percent carbon, from about 0.01 to about 0.03 percent sulfur, from about 0.003 to about 0.010 percent boron, from about 0.004 to about 0.008 percent nitrogen, the balance being iron and impurities incident to the mode of manufacture.
• a cube-on-edge oriented silicon steel having a permeability at H l0 oersteds greater than 1,820 and made in accordance with the process of claim 1.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Metallurgy (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Electromagnetism (AREA)
• Manufacturing Of Steel Electrode Plates (AREA)
• Soft Magnetic Materials (AREA)

Priority Applications (18)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23319003

Family Applications (1)

Country Status (17)

Cited By (14)

Families Citing this family (9)

Citations (6)

Family Cites Families (2)

• 1973
  • 1973-03-01 US US337073A patent/US3873381A/en not_active Expired - Lifetime
• 1974
  • 1974-02-19 CA CA192,894A patent/CA1021671A/en not_active Expired
  • 1974-02-22 ZA ZA00741175A patent/ZA741175B/xx unknown
  • 1974-02-22 GB GB807874A patent/GB1452699A/en not_active Expired
  • 1974-02-27 BE BE141426A patent/BE811618A/xx not_active IP Right Cessation
  • 1974-02-27 IN IN414/CAL/1974A patent/IN141411B/en unknown
  • 1974-02-27 NL NL7402637A patent/NL7402637A/xx not_active Application Discontinuation
  • 1974-02-28 FR FR7406932A patent/FR2219980B1/fr not_active Expired
  • 1974-02-28 CS CS741487A patent/CS212706B2/cs unknown
  • 1974-02-28 AR AR252571A patent/AR203191A1/es active
  • 1974-02-28 JP JP2370974A patent/JPS5423332B2/ja not_active Expired
  • 1974-02-28 SE SE7402698A patent/SE393126B/xx unknown
  • 1974-03-01 RO RO7477875A patent/RO69745A/ro unknown
  • 1974-03-01 ES ES423800A patent/ES423800A1/es not_active Expired
  • 1974-03-01 IT IT48823/74A patent/IT1003625B/it active
  • 1974-03-01 BR BR1511/74A patent/BR7401511D0/pt unknown
  • 1974-03-01 DE DE2409895A patent/DE2409895C3/de not_active Expired

Patent Citations (6)

Also Published As

Similar Documents

Legal Events