Nkk Corporation

Katsumi Nakajima

Takeshi Fujita

Yuji Yamasaki

Toshiaki Urabe

Fusato Kitano

Yoshihiko Oda

Hideki Matsuoka

Tatsuhiko Hiratani

Kunikazu Tomita

Kenji Tahara

Yasuyuki Takada

Nobuo Yamagami

A steel sheet containing 0.004 to 0.02% C, 1.0% or less Si, 0.7 to 3.0% Mn, 0.02 to 0.15% P, 0.02% or less S, 0.01 to 0.1% Al, 0.004% or less N, 0.2% or less Nb, by mass %, optionally Ti, Bi or at least one element selected from the group consisting of Cr Mo, Ni and Cu, and the balance being Fe; the Nb content satisfying a formula of(12/93)&#xd7;Nb*/C&#x2267;1.0,wherein Nb*=Nb&#x2212;(93/14)&#xd7;N, and wherein C, N and Nb designate the content in mass % of carbon, nitrogen and niobium, respectively; and a yield strength and an average grain size of the ferritic grains which satisfy a formula of&#x2266;&#x2212;120+1280,wherein YP designates yield strength in MPa, and d designates an average size of ferritic grains in &#x3bc;m.

Steel sheet

The steel sheet comprises: a ferritic phase having ferritic grains of 10 or more grain size number and ferritic grain boundaries; and at least one kind of Nb precipitates and Ti precipitates. The ferritic grain has a low density region with a low precipitate density in the vicinity of grain boundary. The low density region has a precipitate density of 60% or less to the precipitate density at center part of the ferritic grain. The steel sheet consists essentially of 0.002 to 0.02% C, 1% or less Si, 3% or less Mn, 0.1% or less P, 0.02% or less S, 0.01 to 0.1% sol.Al, 0.007% or less N, at least one element of 0.01 to 0.4% Nb and 0.005 to 0.3% Ti, by mass %, and the balance being Fe.

Steel sheet and method for manufacturing the same

A heat shrink band steel sheet of the present invention comprises on the basis of percent in weight C: 0.1% or less, Si: 0.1% or less, Mn: 0.1 to 2%, P: 0.15% or less, S: 0.02% or less, sol Al: 0.08% or less, and N: 0.005% or less, or C: 0.005% or less, Si: 0.1% or less, Mn: 0.1 to 2%, P: 0.15% or less, S: 0.02% or less, sol Al: 0.08% or less, N: 0.005% or less, Ti: 0.02 to 0.06%, and B: 0.0003 to 0.005%, wherein the product of a magnetic permeability at the magnetic field of 0.3 Oe after heat shrinking treatment and a thickness (mm) is at least 350. A color CRT having a sufficient magnetic shielding characteristic and a less amount of color deviation can be realized by the steel sheet.

Heat shrink band steel sheet and manufacturing method thereof

Growing community of inventors

Fukuyama, Japan

Katsumi Nakajima