Abstract: Disclosed is a melting furnace of metals and melting method thereof, which can control the rate at which a metallic raw material is introduced from a preheating section to a melting section within an optimum range and which can achieve efficient melting of the metallic raw material using oxygen burners only. The metal melting furnace has a melting section (22) provided with oxygen burners (21) and a preheating section (23) for preheating the metallic raw material located above the melting section, with a reduced section (24), having an inner diameter smaller than those of the melting section (22) and of the preheating section (23), being located between the melting section (22) and the preheating section (23).

Abstract: A probe having the inventive composition, it is possible to measure the activity of the solute carbon which could not be measured by the prior art because there did not exist solid oxide or solid composite oxide which were stable at high temperature.The probe comprises a solid electrolyte having a mixed subelectrode provided on its surface, and a reference electrode for providing a predetermined oxygen potential is disclosed. The mixed sub-electrode coating on the solid electrolyte includes a mixture of a carbide MC and of an oxide MO of the element M other than carbon of which the carbide is constituted.

Abstract: An Fe--Ni alloy cold-rolled sheet excellent in cleanliness and etching pierceability prepared as specified in the claims, which consists essentially of: 30 to 45 wt. % nickel, 0.1 to 1 wt. % manganese, 0.003 to 0.03 wt. % aluminum and the balance being iron and incidental impurities comprising up to 0.4 wt. % silicon, up to 0.1 wt. % chromium, up to 0.005 wt. % carbon, up to 0.005 wt. % nitrogen, up to 0.005 wt. % sulfur, up to 0.010 wt. % phosphorus, up to 0.002 wt. % oxygen, and up to 0.002 wt. % as converted into oxygen for non-metallic inclusions. The non-metallic inclusions contain at least CaO, Al.sub.2 O.sub.3 and MgO, and the composition thereof is in a region of a melting point of at least 1,600.degree. C., which region is defined by the liquidus curve of 1,600.degree. C. in the CaO--Al.sub.2 O.sub.3 --MgO ternary phase diagram. The non-metallic inclusions have a particle size of up to 6 .mu.m.

Abstract: A method for manufacturing an Fe-Ni alloy cold-rolled sheet excellent in cleanliness and etching pierceability, comprising: preparing an Fe-Ni molten alloy, containing 30 to 45 wt. % nickel, and subjected to dephosphorization and decarburization; adding aluminum and flux to the Fe-Ni molten alloy in a ladle made of an MgO-CaO refractory containing 20 to 45 wt. %; strongly stirring the Fe-Ni molten alloy which contains the added aluminum and flux in the ladle to produce a CaO-Al.sub.2 O.sub.3 -MgO slag so as to react the Fe-Ni molten alloy with the CaO-Al.sub.2 O.sub.3 -MgO slag to deoxidize the Fe-Ni molten alloy while controlling a value of activity of SiO.sub.2 from 0.001 to 0.005 and a value of activity of Al.sub.2 O.sub.3 from 0.1 to 0.3 in the CaO-Al.sub.2 O.sub.3 -MgO slag, and the CaO-Al.sub.2 O.sub.3 -MgO slag having the following chemical composition: CaO and Al.sub.2 O.sub.3 : at least 57 wt. %, wherein the ratio of CaO/(CaO+Al.sub.2 O.sub.3) being at least 0.45, MgO: up to 25 wt. %, SiO.sub.

Abstract: Molten metal is put under pressure of up to 10 atmospheres in a covered ladle and a gas soluble in the metal is bubbled through the melt. Some gas goes into solution, while the remainder rises in bubbles and brings inclusions suspended in the molten metal up to the surface. Then the pressure is lowered, after which gas comes out of the solution in fine bubbles which also bring impurity inclusions up to the surface. In another method molten steel is refined at pressures not exceeding atmospheric pressure in a covered ladle equipped for evacuation and equipped for bubbling gas through the molten steel bath. Bubbling followed by pressure reduction can then be performed to form two stages of cleaning. Heat may be added for compensating the cooling effect of gas expansion.

Abstract: A method for economically manufacturing an iron-boron-silicon alloy through simple steps, which comprises the steps of: adding a boron raw material and a carbonaceous reducing agent to a molten iron received in a vessel; blowing oxygen gas into the molten iron to reduce the boron raw material in the molten iron by means of the carbonaceous reducing agent to prepare a boron-containing molten iron; continuing the blowing of oxygen gas to decarburize the boron-containing molten iron until the carbon content in the boron-containing molten iron decreases to up to 0.2 wt. %; and adding at least one of silicon and ferrosilicon to the boron-containing molten iron while stirring the boron-containing molten iron, thereby manufacturing an iron-boron-silicon alloy.

Abstract: A method for melting and reducing chrome ore, which comprises charging chrome ore and carbonaceous material, and blowing in oxygen gas under a pressure ranging from 1 to 600 Torr, while molten metal is being stirred by a stirring gas blown in. In this method, a reaction vessel capable of allowing top blowing and bottom blowing onto the molten metal and decreasing pressure within the vessel is employed. Chrome ore and carbonaceous material can be used in the form of lumps or powder. When powdered ore and material are used, they can be injected through a lance or a tuyere into the vessel.