# US 2019/0168274 A1 · Bimetallic tube and method for manufacturing a bimetallic tube > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0168274 A1 - Document ID: US20190168274A1 - Status: Published application - Kind: A1 - Application number: 16/313,240 - Filed: 2017-06-30 - Published: 2019-06-06 - Earliest claimed: 2016-07-01 - Assignees: Sandvik Intellectual Property AB - Applicants: Sandvik Intellectual Property AB - Inventors: James SHIPLEY; Daniel GULLBERG; Robert MATTSSON - Web page: https://patentgrep.com/patent/US20190168274A1 ## CPC - B21C 37/154: {Making multi-wall tubes} - B21C 1/00: Manufacture of metal sheets, wire, rods, tubes or like semi-manufactured products by drawing - B32B 15/013: {one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium} - C22C 16/00: Alloys based on zirconium - C22C 38/001: {containing N} - C22C 38/02: containing silicon - C22C 38/04: containing manganese - C22C 38/08: containing nickel {(C22C38/105 takes precedence)} - C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium - C22C 38/40: with nickel - C22C 38/44: with molybdenum or tungsten - C22C 38/58: with more than 1.5% by weight of manganese - B21C: MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - C22C: ALLOYS (treatment of alloys C21D, C22F) ## Abstract The present disclosure relates to a bimetallic tube comprising a first metallic tube having an inner diameter and an outer diameter, and a second metallic tube having an inner diameter and an outer diameter, wherein the first metallic tube is arranged within and force-fitted to the second metallic tube and wherein the first metallic tube comprises a zirconium (Zr) based alloy and wherein the second metallic tube comprises an austenitic stainless steel. The present disclosure also relates to a method for manufacturing a bimetallic tube comprising the steps of providing a first metallic tube having an inner diameter and an outer diameter, providing a second metallic tube having an inner diameter and an outer diameter, wherein the outer diameter of the first metallic tube is smaller than the inner diameter of the second tube, insetting the first metallic tube into the second metallic tube, cold-drawing the first and second metallic tubes together, such that the first and second metallic tubes are force-fitted together. ## Claims ### Claim 1 A bimetallic tube comprising a first metallic tube having an inner diameter (ID1st) and an outer diameter (OD1st), and a second metallic tube having an inner diameter (ID2nd) and an outer diameter (OD2nd), wherein the first metallic tube is arranged within and force-fitted to the second metallic tube, wherein the first metallic tube comprises, in weight %, Fe+Cr≤1.0; C≤0.1; O≤0.2; Hf≤5.0; balance Zr and normally occurring impurities, wherein the second metallic tube is an austenitic stainless steel comprising, in weight, C≤0.04; Mn≤3.0; P≤0.05; S≤0.04; Si≤1.0; Cr 15.0-30.0; Ni 7.0-25.0; Mo≤1.0; N≤0.10; balance Fe and normally occurring impurities, and wherein the force-fitting of the first metallic tube to the second metallic tube is at least 20 μm determined by the following procedure: measuring the inner diameter (IDBM) of the bimetallic tube; removing the second metallic tube from the first metallic tube; measuring the inner diameter (ID1st) of the first metallic tube after the second metallic tube has been removed; calculating the absolute value of the difference (IDBM−ID1st) between the inner diameter (IDBM) of the bimetallic tube and the inner diameter (ID1st) of the first metallic tube after the second metallic tube has been removed. ### Claim 2 (depends on 1) The bimetallic tube according to claim 1, wherein the content of Cr present in the second metallic tube is in a range of from 17 to 21 weight %. ### Claim 3 (depends on 1) The bimetallic tube according to claim 1, wherein the content of Cr present in the second metallic tube is in a range of from 23 to 27 weight %. ### Claim 4 A method for manufacturing a bimetallic tube comprising the steps of: providing a first metallic tube having an inner diameter (ID1st) and an outer diameter (OD1st), and providing a second metallic tube having an inner diameter (ID2nd) and an outer diameter (OD2nd), wherein the outer diameter (OD1st) of the first metallic tube is smaller than the inner diameter (ID2nd) of the second tube; inserting the first metallic tube into the second metallic tube; and cold-drawing the first and second metallic tubes together, such that the first and second metallic tubes are force-fitted together, wherein in the step of providing the first metallic tube, the first metallic tube comprises, in weight %; Fe+Cr≤1.0; C≤0.1; O≤0.2; Hf≤5.0; balance Zr and normally occurring impurities, wherein in the step of providing the second metallic tube, the second metallic tube is an austenitic stainless steel comprising, in weight %; C≤0.04; Mn≤3.0; P≤0.05; S≤0.04; Si≤1.0; Cr 15.0-30.0; Ni 7.0-25.0; Mo≤1.0; N≤0.10; balance Fe and normally occurring impurities, and wherein after the step of cold-drawing the first metallic tube is force-fitted to the second metallic tube so that the spring back is least 20 μm determined by the following procedure: measuring the inner diameter (IDBM) of the bimetallic tube; removing the second metallic tube from the first metallic tube; measuring the inner diameter (ID1st) of the first metallic tube after the second metallic tube has been removed; and calculating the absolute value of the difference (IDBM−ID1st) between the inner diameter (IDBM) of the bimetallic tube and the inner diameter (ID1st) of the first metallic tube after the second metallic tube has been removed. ### Claim 5 (depends on 4) The bimetallic tube according to claim 4, wherein the content of Cr present in the second metallic tube is in a range of from 17 to 21 weight %. ### Claim 6 (depends on 4) The bimetallic tube according to claim 4, wherein the content of Cr present in the second metallic tube is in a range of from 23 to 27 weight %. ### Claim 7 (depends on 4) The method according to claim 4, wherein in the step of cold-drawing, the outer diameter (OD2nd)of the second tube is reduced 10% or less compared to outer diameter (OD2nd) of the second metallic tube before cold-drawing. ### Claim 8 (depends on 4) The method according to claim 4, wherein in the step of cold-drawing, the outer diameter (OD2nd) of the second tube is reduced 4% or less compared to outer diameter (OD2nd) of the second metallic tube before cold-drawing. ### Claim 9 (depends on 4) The method according to claim 4, wherein after the step of cold-drawing the second metallic tube has an elongation of at least or equal to 35% and a hardness not more than or equal to 90 HRB. ### Claim 10 (depends on 4) The method according to claim 4, wherein in the step of providing the first metallic tube and/or the second metallic tube is heat-treated before the step of inserting the first metallic tube into the second metallic tube. ### Claim 11 (depends on 4) The method according to claim 4, wherein in the steps of providing first and second metallic tubes, the first metallic tube and/or the second metallic tube are cold worked tubes. ### Claim 12 (depends on 4) The method according to claim 4, wherein in the step of providing the first metallic tube, the first metallic tube is a seamless tube. ### Claim 13 (depends on 4) The method according to claim 4, wherein in the step of providing the first metallic tube, the average wall thickness of the first metallic tube is 0.3 mm to 2 mm. ### Claim 14 (depends on 4) The method according to claim 4, wherein in the step of providing the second metallic tube, the second metallic tube is a seamless tube. ### Claim 15 (depends on 4) The method according to claim 4, wherein in the step of providing the second metallic tube, the average wall thickness of the second metallic tube is 0.5 mm to 4 mm. ### Claim 16 (depends on 2) The bimetallic tube according to claim 2, wherein the content of Cr present in the second metallic tube is in a range of from 18 to 20 weight %. ### Claim 17 (depends on 3) The bimetallic tube according to claim 3, wherein the content of Cr present in the second metallic tube is in a range of from 24 to 26 weight %. ### Claim 18 (depends on 5) The bimetallic tube according to claim 5, wherein the content of Cr present in the second metallic tube is in a range of from 18 to 20 weight %. ### Claim 19 (depends on 6) The bimetallic tube according to claim 6, wherein the content of Cr present in the second metallic tube is in a range of from 24 to 26 weight %.