Nippon Steel Corporation

Hajime Nitto

Kango Sakai

Yoshitaka Hiromae

Katushi Saito

Hiromitsu Naito

Kazuo Nakamura

Yasuo Shimokawa

Katusi Saito

Hiromitsu Naitoh

A cold-rolled low carbon steel strip is continuously annealed by rapidly heating the steel strip with a gaseous combustion product which has been prepared at a combustion air ratio of 0.8 or more but less than 1.0 in a direct fired furnace to a temperature of 500.degree. C. to an Ac.sub.3 point of the steel strip at an average heating rate of 30.degree. to 100.degree. C./sec to cause the thickness of a layer of oxides produced on the peripheral surface of the steel strip not to exceed 1,000 angstroms; by maintaining the temperature of the rapidly heated steel strip in a range of from 700.degree. C. to the Ac.sub.3 point, in a reducing atmosphere comprising 4% or more of hydrogen and the balance nitrogen, for at least 10 seconds, to reduce the oxide layer; by cooling the steel strip from at least 600.degree. C. to a desired temperature, at an average cooling rate of 10.degree. to 300.degree. C./sec by using a cooling medium comprising a gas and a liquid; and by eliminating an oxide layer formed on the peripheral surface of the steel strip during the cooling procedure.

Process for continuously annealing a cold-rolled low carbon steel strip

A hot dip galvanized steel strip in which the zinc based alloy coating exhibits a satisfactory appearance and is firmly fixed to the strip substrate, which strip is produced by a process which comprises coating at least one surface of a steel strip with a melted zinc based alloy controlling the weight of the melted zinc based alloy coating and; solidifying the melted zinc based alloy coating and which process is characterized in that the zinc based alloy contains 0.1 to 2.0% by weight of magnesium and in at least a portion of a stage in which the melted zinc based alloy coating is still in the fluid state, the zinc based alloy coating is exposed to an oxygen-controlled atmosphere containing 1000 ppm or less of molecular oxygen, the controlling procedure for the weight of the melted zinc based alloy coating being carried out in the oxygen-controlled atmosphere.

Process for producing a hot dip galvanized steel strip

A metal strip is electrolytically treated by using an apparatus having:

Apparatus for electrolytically treating a metal strip

An annealing separator useful for producing a grain oriented silicon steel strip having an excellent magnetic property, comprises non-hydrating magnesium oxide which has been calcined at a temperature of 1300.degree. C. or more, preferably, from 1300.degree. to 2100.degree. C., and which is in the form of fine particles, 70% by weight of which have a size of 5 microns or less, and optionally, magnesium hydroxide in an amount of 1 to 100% based on the weight of the magnesium oxide and/or an aluminium compound in an amount of 0.05 to 10% based on the weight of the magnesium oxide.

Annealing separator for grain oriented silicon steel strips

In a method for producing a hot strip by hot rough rolling, a steel slab heated to a rolling temperature to obtain a steel band, and hot finishing rolling the steel band in a continuous manner, the improvements comprising overlapping a forward end portion of a steel band which is being rolled by the rough hot rolling over a finishing end portion of a similarly rolled preceding steel band before or during the hot finishing rolling step, with insertion between the overlapped portions of the both hot bands of an oxide scale-fusing agent which reacts with the oxide scale present on the opposing surfaces of the overlapped portions by the heat of the overlapped portions and forms a low-melting point substance, fixing temporarily the overlapped portions by means of a metallic nail-like member driven into the overlapped portions, bonding the overlapped portions by reduction, and subjecting the steel bands thus bonded to the hot finishing rolling continuously.

Growing community of inventors

Kitakyushu, Japan

Hajime Nitto