FERREIRA MARCELO ALMEIDA CUNHA (BR)
DE LIMA MARÍLIA MENDONÇA (BR)
MESQUITA RAFAEL AGNELLI (BR)
FARINA ALEXANDRE BELLEGARD (BR)
LIBERTO RODRIGO CESAR NASCIMENTO (BR)
VILLARES METALS SA (BR)
| AMENDED CLAIMS received by the International Bureau on 31 August 2015 (31.08.2015) (Amended) 1 . MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, for oil and gas application as casing and tubing, characterized by the fact that it comprises a martensitic-ferritic microstructure, and a chemical composition in the range of C: from 0.005 to 0.030%; Si: from 0.10 to 0.40%; Mn from 0.20 to 0.80%; P: 0.020% max; S: 0.005% max; Cr: from 13 to 15%; Ni: from 4.0 to 6.0%; Mo: from 2.0 to 4.5%; V: from 0.01 to 0.10%; Nb: from 0.01 to 0.50%; N: from 0,016 to 0.070%; Al: from 0.001 to 0.060%; Ti: from 0.001 to 0.050%; Cu: from 0.01 to 1 .50%; O: 0.005% max (in weight percent), wherein the balance is performed by Fe and unavoidable impurities from the industrial prossessing and having the localized corrosion parameter (LCP) between 3.2 and 6.2, defined by the equation bellow: LCP = 0.500 - %Cr + 1287 · %Μο + 1.308■ %N - Ξ.984. (Amended) 2. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to the claim 1 , characterized by the fact that it comprises a C content from 0.005 to 0.015%. (Amended) 3. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 2, characterized by the fact that it comprises a Cr content from 13.5 to 14.5%. (Amended) 4. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 3, characterized by the fact that it comprises a Ni content from 4.5 to 5.5%. (Amended) 5. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 4, characterized by the fact that it comprises a Mo content from 3.0 to 4.0%. (Amended) 6. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 5, characterized by the fact that it comprises a Nb content from 0,03 to 0.20% and N content from 0,016 to 0.030%. (Amended) 7. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 5, characterized by the fact that it comprises a Nb content from 0.20 to 0.50% and N content from 0.020 to 0.050%. (Amended) 8. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 7, characterized by the fact that it comprises a Cu content from 0.8 to 1 .2%. (Amended) 9. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 , 2, 4 and 8, characterized by the fact that it comprises a Cr content from 13.5 to 14.5%; Mo content from 3.0 to 4.0%; Nb content from 0,03 to 0.20% and N content from 0,016 to 0.030%. (Amended) 10. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 , 2, 4 and 8, characterized by the fact that it comprises a Cr content from 13.5 to 14.5%; Mo content from 3.0 to 4.0%; Nb content from 0.20 to 0.50 % and N content from 0.020 to 0.050%. (Amended) 1 1 . MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 10, characterized by the fact that it comprises a volumetric fraction of niobium carbonitride between 0,01 and 0,50%. (Amended) 12. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 1 1 , characterized by the fact that it comprises a LCP between 4.2 and 5.2. (Amended) 13. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, according to one of claims 1 to 12, characterized by the fact that it comprises a Pitting Resistance Equivalent Number (PREN) over 24, wherein PREN is defined by PREN=%Cr+3.3%Mo+ 16%N. (Amended) 14. MARTENSITIC-FERRITIC STAINLESS STEEL TUBE, for oil and gas application, according to one of claims 1 to 1 3, characterized by the fact that it has a final microstructure composed by δ ferrite, martensite, retained austenite and residual amounts of deleterious phases such as Chi or Sigma; wherein the amount of δ ferrite ranges from 20 to 50%, the amount of martensite ranges from 50 to 80% and have no more than 15% of retained austenite, and wherein the sum is equal to 100%. (Original) 15. PROCESS FOR PRODUCTION OF SEAMLESS TUBE OF MARTENSITIC-FERRITIC STAINLESS STEEL, characterized by the fact that it comprises the following steps: a) rolling of the tube that comprises the martensitic-ferritic stainless steel, as defined in one of claims 1 to 14, followed by a heat treatment, wherein the heating temperature for the finishing steps shall follow the equation bellow: TProc - 16.9 * %Cr - 49.9 * % o > Ξ 3 Ξ ; b) heat treatment, divided in the following sub steps: b1 ) optionally quenching, and, when present, shall follow the heating temperature equation of step a); b2) single or double tempering, comprising temperatures between 550 and 680°C, directly after rolling or after a thermal cycle of quenching; and c) air or water cooling after quenching or tempering. (Original) 16. PROCESS, according to claim 15, characterized by the fact that the rolling is performed in a mandrel continuous mill or in a Stiefel-type not reversible duo mill (plug mill). (Original) 17. PROCESS, according to one of claims 15 to 16, characterized by the fact that the tube rolling can be done using direct or cold charging for the finishing rolling. 27 |