Abstract: A high-Cr martensite steel pipe having excellent pitting resistance and method for manufacturing the same, which involves forming a pipe of steel including C: about 0.03 wt % or less, Si: about 0.5 wt % or less, Mn: about 0.5-3.0 wt %, Cr: about 10.0-14.0 wt %, Ni: about 0.2-2.0 wt %, Cu: about 0.2-1.0 wt % and N: about 0.03 wt % or less with the balance being Fe and incidental impurities, and having a value X shown as defined in the following formula (1) of about 12.2 or more. The pipe is quenched after austenitizing it at a temperature substantially equal to an A.sub.C3 point or higher, and the pipe is annealed in a temperature range from about 550.degree. C. or higher to a temperature lower than an A.sub.C1 point.

Abstract: High-quality high-speed steel roll which is markedly excellent in abrasion resistance and free of carbide segregation even in the case of production by centrifugal casting of economical benefit; it comprises an outer layer containing, by all weight ratios, C; 2.4-2.9%, Si; not more than 1%, Mn; not more than 1%, Cr; 12-18%, Mo; 3-9%, V; 3-8% and Nb; 0.5-4%, and meeting with the following equations (1) and (2) at one time,0.27.gtoreq.Mo (%)/Cr (%).ltoreq.0.7 (1)C (%)+0.2.multidot.Cr (%).ltoreq.6.2 (2)the outer layer further containing as the balance Fe and unavoidable impurities.

Abstract: A martensitic steel for a line pipe having excellent corrosion resistance and weldability is disclosed. The martensitic steel contains about:0.02 wt % or less of C, 0.50 wt % or less of Si,0.2 to 3.0 wt % of Mn, 10 to 14 wt % of Cr,0.2 to 7.0 wt % of Ni, 0.2 to 5.0 wt % of Mo,0.1 wt % or less of Al, 0.07 wt % or less of N, andthe balance being Fe and incidental impurities; andthese elements satisfy substantially the following equations:(Cr %)+(Mo %)+0.1(N %)-3(C %).gtoreq.12.2,(Cr %)+3.5(Mo %)+10(N %)+0.2(Ni %)-20(C %).gtoreq.14.5, and150(C %)+100(N %)-(Ni %)-(Mn %).ltoreq.4.The martensitic steel may further contain at least one element selected from the group consisting ofabout 2.0 wt % or less of Cu, about 0.15 wt % or less of Ti, about 0.15 wt % or less of Zr, about 0.15 wt % or less of Ta andabout 0.006 wt % or less of Ca, andthese elements satisfy substantially the following equations:(Cr %)+(Mo %)+0.1(N %)+3(Cu %)-3(C %).gtoreq.12.2,(Cr %)+3.5(Mo %)+10(N %)+0.2(Ni %)-20(C %).gtoreq.14.

Abstract: This invention provides bainite steel materials having a less scattering of properties in a thickness direction or between steel materials by using a chemical composition of C: not less than 0.001 wt % but less than 0.030 wt %, Si: not more than 0.60 wt %, Mn: 1.00-3.00 wt %, Nb: 0.005-0.20 wt %, B: 0.0003-0.0050 wt % and Al: not more than 0.100 wt % and rendering not less than 90% of the material into a bainite texture in steel materials such as thick steel plates, steel sheets, section steels, rod steels and the like.

Abstract: A high-Cr martensitic steel pipe having excellent pitting resistance and method for manufacturing the same, which involves forming a pipe of steel including C: about 0.03 wt % or less, Si: about 0.5 wt % or less, Mn: about 0.5-3.0 wt %, Cr: about 10.0-14.0 wt %, Ni: about 0.2-2.0 wt %, Cu: about 0.2-1.0 wt % and N: about 0.03 wt % or less with the balance being Fe and incidental impurities, and having a value X shown as defined in the following formula (1) of about 12.2 or more. The pipe is quenched after austenitizing it at a temperature substantially equal to an Ac.sub.3 point or higher, and the pipe is tempered in a temperature range from about 550.degree. C. or higher to a temperature lower than an Ac.sub.1 point.

Abstract: A roll outer layer material for hot rolling includes, as analyzed in weight percent, of 2.5-4.0% C, 6.0-20% Cr, 3.0-10.0% V, 0.6-5.0% Nb, 2.0-15% Mo, 3.0% or below Si, 3.0% or below Mn, C, V, Nb and Cr satisfying a following formula (1),10.5(%).ltoreq.6.5.C(%)-1.3.V(%)-0.7.Nb(%).ltoreq.2.Cr(%)-2(%)(1), and the balance being Fe and incidental impurities. A method of manufacturing a roll for hot rolling includes the steps of centrifugally casting an outer layer material having the above composition, centrifugally casting graphite steel containing 0.5% or above of C as an intermediate layer, and casting an axis material which is a spheroidal graphite cast iron, a flake graphite cast iron or a graphite steel. C is present in the intermediate layer in an amount which satisfies a following formula (2),C (intermediate layer).gtoreq.2.0-0.5 (C-0.2 V-0.

Abstract: An extra high tensile steel having an excellent stress corrosion cracking resistance in sea water and a yield strength of 1080 MPa or more is provided. A slab comprising, in terms of % by weight, 0.04 to 0.09% of C, 0.01 to 0.10% of Si, 0.05 to 0.65% of Mn, 8.0 to 11.0% of Ni, 0.5 to 1.5% of Mo, 0.2 to 1.5% of Cr, 0.02 to 0.20% of V and 0.01 to 0.08% of Al with the balance consisting of iron and unavoidable impurities is heated to a temperature between 1000.degree. C. and 1250.degree. C., hot rolled at a temperature of Ar' point or above, air-cooled, reheated at a rate of 120.degree. C./min or less to a temperature region of from (A.sub.C3 point--40.degree. C.) to (A.sub.C3 point+40.degree. C.), quenched and subsequently tempered at a temperature of the A.sub.C1 point or below.

Abstract: This invention provides bainite steel materials having a less scattering of properties in a thickness direction or between steel materials by using a chemical composition of C: not less than 0.001 wt % but less than 0.030 wt %, Si: not more than 0.60 wt %, Mn: 1.00-3.00 wt %, Nb: 0.005-0.20 wt %, B: 0.0003-0.0050 wt % and Al: not more than 0.100 wt % and rendering not less than 90% of the material into a bainite texture in steel materials such as thick steel plates, steel sheets, section steels, rod steels and the like.

Abstract: A centrifugal cast roll shell material composed of a granular MC carbide, graphite and C: 2.5 to 4.7%, Si: 0.8 to 3.2%, Mn: 0.1 to 2.0%, Cr: 0.4 to 1.9%, Mo: 0.6 to 5%, V: 3.0 to 10.0% and Nb: 0.6 to 7.0%, satisfying the following formulae (1), (2), (3) and (4):2.0+0.715 V+0.10 Nb.ltoreq.C (%) (1)1.1.ltoreq.Mo/Cr (2)Nb/V.ltoreq.0.8 (3)0.2.ltoreq.Nb/V (4),the remainder being Fe and inevitable impurities, wherein the pouring temperature is 1,400.degree. C. or higher.

Abstract: A roll outer layer material for hot rolling consists essentially, as analyzed in weight percent, of 2.5-4.0% C, 6.0-20% Cr, 3.0-10.0% V, 0.6-5.0% Nb, 2.0-15% Mo, 3.0% or below Si, 3.0% or below Mn, C, V, Nb and Cr satisfying a formula where 10.5.ltoreq.6.5.C(%)--1.3.V(%)--0.7.Nb(%).ltoreq.2.Cr(%)--2, and the balance being Fe and incidental impurities. A method of manufacturing a roll for hot rolling comprises the steps of centrifugally casting an outer layer material having the above composition, centrifugally casting graphite steel containing 0.5% or above of C as an intermediate layer, and casting an axis material which is a spheroidal graphite cast iron, a flake graphite cast iron or a graphite steel. Carbon is present in the intermediate layer in an amount which satisfies a formula, C (intermediate layer).gtoreq.2.0-0.5?C(%)--0.2.V(%)--0.11.Nb(%)! (outer layer).

Abstract: Steel having excellent vibration-damping properties and weldability includes about 0.02 wt % or less of C, about 0.02 wt % or less of Si, and about 0.08 wt % or less of Mn. This steel also includes about 0.05 to 1.5 wt % of Cu, about 1.0 to 7.0 wt % of Al, about 0.008 wt % or less of N, and Fe and incidental impurities which together constitute the remaining wt %.