Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/04—Removing impurities by adding a treating agent
  • C21C7/076—Use of slags or fluxes as treating agents
• • 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

Definitions

• the present invention relates to a product for refining effervescent, quiescent and semi-quiescent steel in the casting.
• traces of refractory material or of lime may be carried along by the molten steel, either into the middle or just underneath the skin of the ingot.
• bubbles may be produced at such points and form objectionable inclusions which often lead to the production of undesirable lines during subsequent rolling.
• the steel is subjected to the action of energetically stirred air which saturates the steel ⁇ m'th oxygen which is associated with that of the oxides already contained in the metal.
• the conventional methods of purification resort to silicon as a purifying agent, in the form of a Fe-Si or Fe-Cr-Si alloy or the like silicon alloy with low carbon contents, or else, to aluminium, or a mixture of silicon and aluminium, or again, to manganese alloyed with iron or in the form of aptaisen.
• the formation of slags by the inclusions is more marked when the steel is more fluid, that is when it is hotter and when the inclusions are larger.
• alkaline or the like fluorinated derivatives are used, either in admixture with suitable derivatives of boron, or as chemical combinations with the latter, e.g. in the form of fluoborates, either alone or in association with alkaline or the like hydroborons.
• a flux such as e.g. fluorides, chiefly sodium, lithium or potassium fluorides and a reducing agent such as carbon, silicon, manganese or aluminium.
• the reduction is activated by the presence of alkaline carbonates, the basic character of which forms an essential factor for such a reduction.
• a typical composition of such refining powders is as follows, by weight:
• the anhydrous alkaline borates are admixed with alka line fluorides by incorporating with the mixture alkaline carbonates and highly subdivided carbon in a stable condition, such as graphite, or else, boric acid is admixed with alkaline fluorides in the presence of alkaline fluxes, or again, alkaline fluorides or the like fluoborates are admixed with fluoboric acid or alkaline or the like fluorides, fluosilicates or fluotitanates.
• the alkaline derivatives may be replaced entirely or partly by fluorides of rare earth elements, such as cerium fluoride, fluoborate or fluosilicate.
• the carbon may be replaced in the above mixtures, either partly or entirely, by elements of the fourth group of Mendeleevs Periodic Table. Boron may be replaced similarly in the above mixtures, either totally or partly, by elements of the third group such as titanium.
• the steels with which the mixture may be incorporated are chiefly effervescent steels, but it may also be incorporated, under certain conditions, with quiescent or semiquiescent steels.
• the powder tobe incorporated with the steel should, in its most active form, contain a proportion of the solvent and reducing product as high as and even and never underneath these values, so as to prevent the slag formed from showing a too great compacity.
• the product obtained is introduced into the molten steel in amounts lower than or equal to 0.1 kg. per metric ton, but the conditions of operation may require lowering these amounts down to 0.01 kg, or else, one uses 1 or even 2 kg. per metric ton.
• a large fraction of the nitrides formed is solubilized in the fluid slag produced under the action of the refining powder and the boronitrides, formed during operation and which are stable up to 2,000 C., modify substantially the crystalline structure and lead to a clear improvement in the grade of the steel, this being due, in particular, to a substantial increase in the mechanical resistance of the latter.
• the product may be added, either by a shovel, at the moment of the casting in a ladle orin an ingot mold, or else, it maybe introduced inside gauged cardboard boxes, each of which contains an accurate weight of the product adapted for the casting conditions and the grade of the steel. It may also be carried by blisterpreventing cardboards, generally positioned at the bottom of the ingot mold, before the casting, and this increases not only the protective action of these cardboards, but also forms a reliable safeguard, whereby one makes sure the product has been actually added at the proper moment during the casting. Lastly, it allows obtaining through adjustment of the length of the cardboard introduced into the ingot mold, the automatic measurement of the product in accordance with the size of the block.
• Example 1 22 metric tons of mild steel are treated with 120 kg.
• Example 2 50 metric tons of steel for strip iron are treated with 250 kg. of an alloy of Fe-Mn and 30 kg. of anthracite and there is added at the moment of the casting 1,000 gr. of the same refining powder into an ingot mold for ingets of 7 tons.
• Total waste treated steel 2.9%; non-treated steel 13%.
• said contents are lowered from 0.015% down to 0.004% through a treatment of 25 tons of steel by 50 kg. of the refining powder.
• the steels treated in accordance with the present invention may be considered as more highly refined from all points of view.
• An alkaline refining product for steel adapted to be incorporated into said steel during its casting at a ratio of 0.01 kg. to 2 kg. per metric ton
• said alkaline refining product consisting of a mixture about of anhydrous borax, about 10% of sodium fluoride,

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Continuous Casting (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=35615539

Family Applications (1)

Country Status (5)

Cited By (5)

Families Citing this family (1)

Citations (6)

• 1960
  • 1960-01-21 FR FR6841A patent/FR1245440A/fr not_active Expired
  • 1960-05-25 FR FR6915A patent/FR77793E/fr not_active Expired
• 1961
  • 1961-01-19 US US83619A patent/US3158466A/en not_active Expired - Lifetime
  • 1961-01-20 BE BE599338A patent/BE599338A/fr unknown
  • 1961-01-20 DE DE1408878*CA patent/DE1408878C3/de not_active Expired
  • 1961-01-20 GB GB2327/61A patent/GB979427A/en not_active Expired

Patent Citations (6)

Also Published As

Similar Documents