Patent application number | Description | Published |
20080216928 | Seamless steel pipe for line pipe and a method for its manufacture - A seamless steel pipe for line pipe having high strength and stable toughness and having resistance to sulfide corrosion cracking at low temperatures to room temperature is provided. A seamless steel pipe according to the present invention has a chemical composition comprising, in mass percent, C: 0.03-0.08%, Si: 0.05-0.5%, Mn: 1.0-3.0%, Mo: greater than 0.4% to 1.2%, Al: 0.005-0.100%, Ca: 0.001-0.005%, a remainder of Fe and impurities including N, P, S, O, and Cu, with the impurities containing at most 0.01% of N, at most 0.05% of P, at most 0.01% of S, at most 0.01% of O, and at most 0.1% of Cu, and having a microstructure comprising a bainitic-martensitic dual phase structure. | 09-11-2008 |
20080219878 | Seamless steel pipe for line pipe and a process for its manufacture - A thick-walled seamless steel pipe for line pipe which has a high strength and improved toughness and corrosion resistance in spite of the thick wall and which is suitable for use as a riser and flow line has a chemical composition comprising, in mass percent, C: 0.02-0.08%, Si: at most 0.5%, Mn: 1.5-3.0%, Al: 0.001-0.10%, Mo: greater than 0.4%-1.2%, N: 0.002-0.015%, at least one of Ca and REM in a total amount of 0.0002-0.007%, and a remainder of Fe and impurities, with the impurities having the content of P: at most 0.05%, S: at most 0.005%, and O: at most 0.005%, the chemical composition satisfying the inequality: 0.8≦[Mn]×[Mo]≦2.6, wherein [Mn] and [Mo] are the numbers equivalent to the contents of Mn and Mo, respectively, in mass percent. | 09-11-2008 |
20080257459 | Seamless steel pipe and manufacturing method thereof - The present invention relates to the following seamless steel pipes excellent in strength, toughness and weldability, particularly suitable for submarine flow lines, and a manufacturing method thereof. | 10-23-2008 |
20080283161 | High strength seamless steel pipe excellent in hydrogen-induced cracking resistance and its production method - The present invention relates to a high strength seamless steel pipe excellent in hydrogen-induced cracking resistance, characterized by consisting of, by mass %, C: 0.03-0.11%, Si: 0.05-0.5%, Mn: 0.8-1.6%, P: 0.025% or less, S: 0.003% or less, Ti: 0.002-0.017%, Al: 0.001-0.10%, Cr: 0.05-0.5%, Mo: 0.02-0.3%, V: 0.02-0.20%, Ca: 0.0005-0.005%, N: 0.008% or less and O (Oxygen): 0.004% or less, and the balance Fe and impurities, and also characterized in that the microstructure of the steel is bainite and/or martensite, ferrite is precipitated at grain boundaries and yield stress is 483 MPa or more. Further, to ensure high strength of the steel, the seamless steel pipe preferably contains, by mass %, at least one of Cu: 0.05-0.5% and Ni: 0.05-0.5%. To produce the above-mentioned steel pipe, it is desirable to limit a starting temperature of quenching after rolling, a cooling rate and a tempering temperature. By this configuration a seamless steel pipe having an yield stress of 483 MPa or more and excellent HIC resistance, which is suitable for a pipeline, can be provided. | 11-20-2008 |
20090023506 | Induction hardened hollow driving shaft - The present invention provides an induction-hardened hollow driving shaft that comprises, as a raw material, a steel pipe that contains, by mass %, 0.30 to 0.47% C, 0.5% or less Si, 0.3 to 2.0% Mn, 0.018% or less P, 0.015% or less S, 0.15 to 1.0% Cr, 0.001 to 0.05% Al, 0.005 to 0.05% Ti, 0.004% or less Ca, 0.01% or less N, 0.0005 to 0.005% B and 0.0050% or less O (oxygen) and the balance Fe and impurities and of which Beff defined by an equation (a) or (b) below is 0.0001 or more, wherein a prior austenite grain size number (JIS G0551) after the hardening is 9 or more. Here, in the case of Neff=N−14×Ti/47.9≧0, Beff=B×10.8×(N−14×Ti/47.9)/14 . . . (a), and, in other cases, Beff=B . . . (b). According to the present invention, a hollow driving shaft that is simultaneously provided with excellent cold workability, hardenability, toughness and torsional fatigue strength and can exert stable fatigue lifetime can be obtained and can be widely utilized. | 01-22-2009 |
20090114318 | Seamless steel pipe for line pipe and a process for its manufacture - A seamless steel pipe for line pipe having a high strength and good toughness and corrosion resistance even though having a thick wall has a chemical composition comprising, in mass percent, C: 0.02-0.08%, Si: at most 0.5%, Mn: 1.5-3.0%, Al: 0.001-0.10%, Mo: greater than 0.4% to 1.2%, N: 0.002-0.015%, Ca: 0.0002-0.007%, and a remainder of Fe and impurities, wherein the contents of the impurities are at most 0.03% for P, at most 0.005% for S, at most 0.005% for O and less than 0.0005% for B and wherein the value of Pcm calculated by the following Equation (1) is at least 0.185 and at most 0.250. The steel pipe has a microstructure which primarily comprises bainite and which has a length of cementite of at most 20 micrometers: | 05-07-2009 |
20090145525 | INDUCTION HARDENED HOLLOW DRIVING SHAFT - The present invention provides an induction-hardened hollow driving shaft that comprises, as a raw material, a steel pipe that contains, by mass %, 0.30 to 0.47% C, 0.5% or less Si, 0.3 to 2.0% Mn, 0.018% or less P, 0.015% or less S, 0.15 to 1.0% Cr, 0.001 to 0.05% Al, 0.005 to 0.05% Ti, 0.004% or less Ca, 0.01% or less N, 0.0005 to 0.005% B and 0.0050% or less O (oxygen) and the balance Fe and impurities and of which Beff defined by an equation (a) or (b) below is 0.0001 or more, wherein a prior austenite grain size number (JIS G0551) after the hardening is 9 or more. Here, in the case of Neff=N−14×Ti/47.9≧0, Beff=B−10.8×(N−14×Ti/47.9)/14 . . . (a), and, in other cases, Beff=B . . . (b). According to the present invention, a hollow driving shaft that is simultaneously provided with excellent cold workability, hardenability, toughness and torsional fatigue strength and can exert stable fatigue lifetime can be obtained and can be widely utilized. | 06-11-2009 |
20100236670 | HEAVY WALL SEAMLESS STEEL PIPE FOR LINE PIPE AND A MANUFACTURING METHOD THEREOF - A method of manufacturing a heavy wall seamless steel pipe for line pipe with a high strength and increased toughness, which is characterized by cooling rate, heating condition for piercing, and heat treating after pipe making,
| 09-23-2010 |
20110226378 | HIGH-STRENGTH STAINLESS STEEL PIPE EXCELLENT IN SULFIDE STRESS CRACKING RESISTANCE AND HIGH-TEMPERATURE CARBONIC-ACID GAS CORROSION RESISTANCE - The problem to be solved is the provision of a high-strength stainless steel pipe having a sufficient corrosion resistance in a high-temperature carbonic acid gas environment and having an excellent sulfide stress cracking resistance at normal temperature. | 09-22-2011 |
20120031530 | STAINLESS STEEL FOR OIL WELL, STAINLESS STEEL PIPE FOR OIL WELL, AND METHOD OF MANUFACTURING STAINLESS STEEL FOR OIL WELL - The chemical composition of a stainless steel in accordance with the present invention consists of C: not more than 0.05%, Si: not more than 0.5%, Mn: 0.01 to 0.5%, P: not more than 0.04%, S: not more than 0.01%, Cr: more than 16.0 and not more than 18.0%, Ni: more than 4.0 and not more than 5.6%, Mo: 1.6 to 4.0%, Cu: 1.5 to 3.0%, Al: 0.001 to 0.10%, and N: not more than 0.050%, the balance being Fe and impurities, and satisfies Formulas (1) and (2). Also, the micro-structure thereof contains a martensitic phase and a ferritic phase having a volume ratio of 10 to 40%, and the ferritic phase distribution ratio is higher than 85%. | 02-09-2012 |
20120031534 | METHOD FOR PRODUCING HIGH-STRENGTH Cr-Ni ALLOY SEAMLESS PIPE - A method for producing a high-strength Cr—Ni alloy seamless pipe comprising preparing an alloy billet with a chemical composition consisting, by mass %, of C: 0.05% or less, Si: 1.0% or less, Mn: less than 3.0%, P: 0.005% or less, S: 0.005% or less, Cu: 0.01 to 4.0%, Ni: 25% or more and less than 35%, Cr: 20 to 30%, Mo: 0.01% or more and less than 4.0%, N: 0.10 to 0.30%, Al: 0.03 to 0.30%, O (oxygen): 0.01% or less, REM (rare earth metal): 0.01 to 0.20%, and the balance being Fe and impurities, and satisfying the formula N×P/REM≦0.10, wherein P, N and REM represent the contents (mass %) of P, N and REM, respectively. The pipe is hot worked using cross roll piercing, solution heat treated, and cold worked. The pipe is excellent in hot workability, stress corrosion cracking and does not laminate during cross piercing. | 02-09-2012 |
20120118441 | METHOD OF MANUFACTURING HEAVY-WALL SEAMLESS STEEL PIPE - A steel pipe with a wall thickness over 30 mm is subjected to heat treatment of quenching and tempering using a temperature range of at least not less than 750° C. during the heating stage, makes it possible to obtain a heavy-wall seamless steel pipe having excellent toughness by resulting grain refinement. Quenching is by performing water cooling after heating the steel pipe to a temperature in the range of not less than 900° C. to not more than 1000° C. by using, as a heating means, induction heating at a frequency of not more than 200 Hz. Tempering is performed at a temperature in the range of not less than 500° C. to not more than 750° C. Preferably, after the heating by induction heating, a soaking treatment is performed in the temperature range of not less than 900° C. to not more than 1000° C. for 10 minutes or less followed by water cooling. | 05-17-2012 |
20120267014 | METHOD FOR MANUFACTURING SEAMLESS STEEL PIPE FOR LINE PIPE AND SEAMLESS STEEL PIPE FOR LINE PIPE - There is provided a method for manufacturing a seamless steel pipe for line pipe, capable of improving the toughness of the seamless steel pipe for line pipe. A round billet having a chemical composition, by mass percent, of C: 0.02 to 0.15%, Si: at most 0.5%, and Mn: 0.5 to 2.5%, the balance being Fe and impurities, is heated. The heated round billet is piercing-rolled to produce a hollow shell. The hollow shell is elongated and rolled and sized to produce a seamless steel pipe. The seamless steel pipe is water cooled, and the water cooling is stopped when the temperature of the seamless steel pipe reaches at most 450° C. The water-cooled seamless steel pipe is quenched, and the quenched seamless steel pipe is tempered. | 10-25-2012 |
20120328897 | HIGH-STRENGTH STAINLESS STEEL FOR OIL WELL AND HIGH-STRENGTH STAINLESS STEEL PIPE FOR OIL WELL - A high-strength stainless steel for oil well having corrosion resistance excellent in a high-temperature environment, having excellent SSC resistance at normal temperature, and having better workability than 13% Cr steels has a chemical composition containing, by mass percent, C: at most 0.05%, Si: at most 1.0%, Mn: at most 0.3%, P: at most 0.05%, S: less than 0.002%, Cr: over 16% and at most 18%, Mo: 1.5 to 3.0%, Cu: 1.0 to 3.5%, Ni: 3.5 to 6.5%, Al: 0.001 to 0.1%, N: at most 0.025%, and O: at most 0.01%, the balance being Fe and impurities, a microstructure containing a martensite phase, 10 to 48.5%, by volume ratio, of a ferrite phase and at most 10%, by volume ratio, of a retained austenite phase, yield strength of at least 758 MPa and uniform elongation of at least 10%. | 12-27-2012 |