Kawasaki Steel Corporation

The Yokohama Rubber Co., Ltd.

Kawatetsu Wire Products Company Ltd.

Kozo Tsunoyama

Takashi Obara

Saiji Matsuoka

Susumu Satoh

Susumu Sato

Mitsumasa Kurosawa

Toshio Irie

Susumu Okada

Hideo Suzuki

Susumu Masui

Masatoshi Shinozaki

Makoto Imanaka

Toshio Ichida

Hideo Abe

Shunichi Tsugawa

Shunichi Harada

Shigeru Kobayashi

Masamitsu Takei

Yoshitaka Udagawa

Kunihiko Kataoka

An extra-low carbon cold rolled steel sheet useful for use in automobiles and the like, having an improved spot weldability is obtained by combining and adding Ti, Nb and B in predetermined amounts to an extra-low carbon steel to control the amount of fine Ti precipitate dispersed in steel to within a specified reasonable range. Furthermore, the spot weldability is improved by controlling the production conditions of the extra-low carbon steel sheet to within specified reasonable ranges.

Cold rolled steel sheets having improved spot weldability

An extra-low carbon cold rolled steel sheet useful for use in automobiles, and the like, having an improved spot weldability is obtained by combining and adding Ti, Nb and B in predetermined amounts to the extra-low carbon steel to control the amount of fine Ti precipitate dispersed in steel to within a specified reasonable range. Furthermore, the spot weldability is improved by controlling the production conditions of the extra-low carbon steel sheet to within specified reasonable ranges.

Method for producing cold rolled steel sheets having improved spot

A method of manufacturing formable as-rolled thin steel sheets having excellent ridging resistance and other properties is disclosed, which comprises rolling a low carbon steel to a given thickness without cold rolling and recrystallization annealing steps. In this rolling, at least one rolling pass is carried out within a given temperature range at high draft and high strain rate.

Method of manufacturing formable as-rolled thin steel sheets

A cold-rolled steel sheet for deep drawing having an improved bake hardenability is disclosed, which comprises 0.005-0.015 wt% of C, not more than 1.0 wt% of Si, not more than 1.0 wt% of Mn, not more than 0.15 wt% of P, 0.0005-0.10 wt% of Al, not more than 0.003 wt% of S and not more than 0.004 wt% of N provided that S+N is not more than 0.005 wt%, and Ti satisfying 1.ltoreq.Ti*/C.ltoreq.20, in which Ti* (%)=Ti(%)-48/14N(%)-48/32S(%). Such a cold-rolled steel sheet is obtained by continuously annealing the steel sheet after the cold rolling, provided that a residence time over a temperature region above recrystallization temperature is within 300 seconds.

Method of manufacturing cold-rolled steel sheets

Thin steel sheets having an improved processability are produced when a steel sheet or cast strip obtained through a continuous casting or strip caster process is subjected to a lubrication rolling step at a temperature of from Ar.sub.3 transformation point to 300.degree. C. and a rolling speed of not less than 1,500 m/min. By this method, the cold rolling step or cold rolling-annealing step can be omitted.

Method of producing thin steel sheets having an improved processability

A cold rolled steel sheet or plated steel sheet having an improved press formability as well as excellent phosphatability, resistance to galling and spot weldability is produced by controlling a surface roughness pattern of the steel sheet so as to satisfy a center-line average surface roughness of 0.3-2.0 .mu.m and a regularity parameter in at least one direction of not more than 0.25 defining the regularity of surface roughness.

Cold rolled steel sheets having an improved press formability

A cold-rolled steel sheet for deep drawing having an improved bake hardenability, which comprises 0.005-0.015 wt % of C, not more than 1.0 wt % of Si, not more than 1.0 wt % of Mn, not more than 0.15 wt % of P, 0.005-0.10 wt % of Al, not more than 0.003 wt % of S and not more than 0.004 wt % of N provided that S+N is not more than 0.005 wt %, and Ti satisfying 1.ltoreq.Ti*/C.ltoreq.20, in which Ti*(%)=Ti(%)-(48/14)N(%)-(48/32)S(%). Such a cold-rolled steel sheet is obtained by continuously annealing the steel sheet after the cold rolling, provided that a residence time over a temperature region above recrystallization temperature is within 300 seconds.

Cold-rolled steel sheets

A process for producing a formable thin steel sheet excellent in ridging resistance. Said process comprises finishing a low carbon steel at a strain rate of not less than 300 (s.sup.-1) in a temperature range of 800.degree. to 300.degree. C. in at least one pass when the low carbon steel is rolled into a specified thickness, and subsequently performing recrystallization annealing.

Production of formable thin steel sheet excellent in ridging resistance

An improved wire with an excellent adhesion with rubber is disclosed for reinforcing rubber goods, made by a diffusion process wherein oxides formed on the surface of plated metal during diffusion are removed before drawing.

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Chiba, Japan

Kozo Tsunoyama