High tensile steel and process for producing the same
AssigneeNippon Steel Corporation
InventorsKatutoshi Ina, Kazuo Yamamoto, Hirokichi Higashiyama, Norio Ishikawa, Hiroshi Miyoshi
Life of this patent
Estimating the term…
Abstract
A high tensile steel which has a satisfactory yield strength of 60 kg/mm.sup.2 or more and excellent resistances to sulfide corrosive cracking and corrosion, and which comprises, as indispensable components, 0.05 to 0.50 wt % of C, 0.1 to 1.0 wt % of Si, 0.1 to 2.0 wt % of Mn, 0.05 to 1.50 wt % of Co and the balance consisting of Fe, is produced by hot- or cold-rolling it, rapidly heating the rolled steel to austenitize it, quenching the austenitized steel and, finally, tempering the quenched steel at a temperature not higher than the Ac.sub.1 point of the steel.
Claims11
A high tensile steel having excellent resistance to sulfide corrosion cracking and corrosion which steel has substantially a martensite structure and a yield strength of 60 to 81 kg/mm.sup.2 and which steel has been prepared by hot- or cold-rolling a steel consisting essentially of, as indispensable components, 0.05% to 0.50% by weight of carbon, 0.1% to 0.28% by weight of silicon, 0.1% to 2.0% by weight of manganese, 0.05% to 1.50% by weight of cobalt, and the balance consisting of iron and inevitable impurities;
- said high tensile steel being produced by rapidly heating said rolled steel to a temperature of from 850.degree. C. to 950.degree. C. at a heating rate of 2.degree. C./ sec or more to austenitize it;
- then quenching said austenitized steel by using water or oil;
- and tempering said quenched steel at a temperature not higher than Ac.sub.1 point of said steel.
A process for producing a high tensile steel having substantially a martensite structure and a yield strength of 60 to 81 kg/mm.sup.2 and exhibiting excellent resistance to sulfide corrosion cracking and corrosion, which comprises the steps of:
- hot- or cold-rolling a steel consisting essentially of, as indispensable components, 0.05% to 0.50% by weight of carbon, 0.1% to 0.28% by weight of silicon, 0.1% to 2.0% by weight of manganese, 0.05% to 1.50% by weight of cobalt, and the balance consisting of iron and inevitable impurities;
- rapidly heating said rolled steel to a temperature of from 850.degree. C. to 950.degree. C. at a heating rate of 2.degree. C./ sec or more to austenitize it;
- quenching said austenitized steel by using water or oil;
- and
- tempering said quenched steel at a temperature not higher than the Ac.sub.1 point of said steel.
Dependencies are inferred from the claim text.