FLOWFORMING CORROSION RESISTANT ALLOY TUBES

1 . A process for the production of a tube comprising:

deforming a corrosion resistant alloy plate to form a hollow cylindrical preform having a longitudinal seam region located between two abutting ends of the deformed plate;

welding the longitudinal seam region to join together the abutting ends; and

flowforming the hollow cylindrical preform to produce a corrosion resistant alloy tube.

2 . The process of claim 1 , wherein the hollow cylindrical preform is formed from the plate such that grains of the corrosion resistant alloy are substantially oriented in the longitudinal direction of the preform.

3 . The process of claim 1 , wherein deforming the corrosion resistant alloy plate to form the hollow cylindrical preform comprises roll bending the corrosion resistant alloy plate.

4 . The process of claim 1 , further comprising machining or grinding the corrosion resistant alloy plate to a flatness of ±0.020 inch (±0.508 mm), wherein the machining or grinding is performed before the deforming.

5 . The process of claim 1 , wherein the welding is performed in a nitrogen atmosphere.

6 . The process of claim 1 , wherein the welding is performed using a filler-less welding technique.

7 . The process of claim 1 , wherein the welding comprises laser welding the longitudinal seam region to join together the abutting ends.

8 . The process of claim 7 , wherein the laser welding is performed in a nitrogen atmosphere.

9 . The process of claim 1 , wherein the welding comprises tungsten inert gas welding (TIG), metal inert gas welding (MIG), or plasma arc welding.

10 . The process of claim 1 , wherein the welding is performed using a filler weld alloy that is the same as the alloy of the preform or is over-alloyed with at least one austenite stabilizing element.

11 . The process of claim 1 , further comprising radially expanding the welded hollow cylindrical preform before the flowforming.

12 . The process of claim 11 , wherein the welded hollow cylindrical preform is radially expanded by at least 0.5%.

13 . The process of claim 1 , further comprising removing weld kerf from the welded longitudinal seam region.

14 . The process of claim 13 , wherein removing weld kerf comprises burnishing or skiving the weld kerf.

15 . The process of claim 1 , further comprising annealing the welded hollow cylindrical preform after the welding and before the flowforming.

16 . The process of claim 15 , wherein the annealing comprises heating the preform to a surface temperature in the range of 1010° C. to 1177° C. (1850-2150° F.).

17 . The process of claim 15 , wherein the annealing recrystallizes at least a heat affected zone of the welded preform.

18 . The process of claim 15 , further comprising quenching the hollow cylindrical preform after the annealing.

19 . The process of claim 18 , wherein the preform is quenched from annealing temperature after no more than 30 minutes time-at-temperature.

20 . The process of claim 18 , wherein the quenching is performed at a cooling rate that prevents the precipitation of deleterious phases during the cooling.

21 . The process of claim 18 , wherein the quenching comprises water quenching.

22 . The process of claim 1 , wherein the flowforming comprises reverse flowforming.

23 . The process of claim 1 , comprising flowforming the hollow cylindrical preform at a cold working temperature to a reduction-of-area of 25% to 75%.

24 . The process of claim 1 , comprising flowforming the hollow cylindrical preform at a cold working temperature to a reduction-of-area of 30% to 65%.

25 . The process of claim 1 , flowforming the hollow cylindrical preform in a single pass to produce the corrosion resistant alloy tube.

26 . The process of claim 1 , further comprising annealing the flowformed tube.

27 . The process of claim 1 , wherein the corrosion resistant alloy comprises a martensitic stainless steel, a martensitic/ferritic stainless steel, a duplex stainless steel, a super duplex stainless steel, a hyper duplex stainless steel, an austenitic stainless steel, an austenitic nickel base alloy, an austenitic nickel base superalloy, or a titanium base alloy.

28 . The process of claim 1 , wherein the corrosion resistant alloy comprises a duplex stainless steel, a super duplex stainless steel, or a hyper duplex stainless steel.

29 . The process of claim 1 , wherein the corrosion resistant alloy comprises a super duplex stainless steel having a volume fraction of ferrite ranging from 35% to 55%, or a duplex stainless steel having a volume fraction of ferrite ranging from 40% to 60%.

30 . The process of claim 1 , wherein the corrosion resistant alloy comprises a nickel base alloy or a titanium base alloy.

31 . A tube produced by the process of claim 1 .

32 . The tube of claim 31 , wherein the tube has a yield strength of 110-160 ksi (758-1,103 MPa).

33 . The tube of claim 31 , wherein the tube has an ultimate tensile strength of at least 125 ksi (862 MPa).

34 . The tube of claim 31 , wherein the ultimate tensile strength of the tube is at least 10 ksi (70 MPa) greater than the yield strength.

35 . The tube of claim 31 , wherein the tube has an elongation of at least 9%.

36 . The tube of claim 31 , wherein the tube has a yield strength of at least 125 ksi (862 MPa), an ultimate tensile strength of at least 130 ksi (896 MPa), an elongation of at least 10%, and an HRC hardness number no greater than 37.

37 . The tube of claim 31 , wherein the tube has an outside diameter of at least 7.0 inches (177.8 mm), wall thickness of at least 0.231 inches (5.87 mm), and a length of at least 34.0 feet (10.4 meters).

38 . The tube of claim 31 , wherein the tube has an outside diameter of at least 9.625 inches (244.5 mm), wall thickness of at least 0.312 inches (7.92 mm), and a length of at least 36.0 feet (11.0 meters).

39 . The tube of claim 31 , wherein the corrosion resistant alloy comprises a super duplex stainless steel having a volume fraction of ferrite ranging from 35% to 55%, or a duplex stainless steel having a volume fraction of ferrite ranging from 40% to 60%, and wherein the tube has a yield strength of at least 110 ksi (758 MPa), an ultimate tensile strength of at least 125 ksi (862 MPa), an elongation of at least 9%, and an HRC hardness number no greater than 38.

40 . The tube of claim 31 , wherein the tube complies with ANSI/API Specification 5CRA, first edition, February 2010.

41 . A process for the production of a tube comprising:

deforming a stainless steel plate to form a hollow cylindrical preform having a longitudinal seam region located between two abutting ends of the deformed plate, the stainless steel comprising a duplex, super duplex, or hyper duplex stainless steel;

laser welding the longitudinal seam region to join together the abutting ends;

annealing the laser welded preform; and

reverse flowforming the laser welded hollow cylindrical preform at a cold working temperature to produce a stainless steel tube.