	US 12,276,014 B2
	High strength micro alloyed steel seamless pipe for sour service and high toughness applications
Vicente Braz Da Trindade Filho, Boulogne-Billancourt (FR); Julio Marcio Silveira E Silva, Boulogne-Billancourt (FR); Cedric Linne, Boulogne-Billancourt (FR); and Ana Carolina Caldas Vilas Boas, Boulogne-Billancourt (FR)
Assigned to VALLOUREC TUBES FRANCE, Meudon (FR)
Filed by VALLOUREC TUBES FRANCE, Boulogne-Billancourt (FR)
Filed on Sep. 17, 2019, as Appl. No. 16/572,918.
Claims priority of application No. 18195795 (EP), filed on Sep. 20, 2018.
Prior Publication US 2020/0095658 A1, Mar. 26, 2020
Int. Cl. C22C 38/04 (2006.01); C21D 8/10 (2006.01); C22C 38/44 (2006.01); C22C 38/48 (2006.01); F16L 9/02 (2006.01)

CPC C22C 38/04 (2013.01) [C21D 8/105 (2013.01); C22C 38/44 (2013.01); C22C 38/48 (2013.01); F16L 9/02 (2013.01)]

16 Claims

1. A steel having a yield strength of at least 485 MPa and having a chemical composition consisting of, in weight %, relative to the total weight of the chemical composition,

0.05≤C≤0.10,

0.15≤Si≤0.35,

1.20≤Mn≤1.50,

0.02≤Cr≤0.08,

0.10<Mo≤0.30,

0.015≤Al≤0.040,

0.002≤N≤0.012,

0.10≤Ni≤0.30,

0.03≤V≤0.04,

0.02≤Nb≤0.028, and

0.001≤Ti≤0.025,

wherein

a content of V+Nb is 0.07 wt % or less,

the balance of the chemical composition of the steel is constituted by Fe and at least one residual element selected from the group consisting of P, S, B, Ca, Cu and a mixture thereof,

the chemical composition of the steel satisfies the following formula wherein contents of C, Cr, Mo, Nb, V and Ti are expressed in weight %;

C+Cr+Mo+Nb+V+Ti≤0.55,

wherein the steel has an absorbed energy of from 390 J to 405 J at a temperature of from −80° C. to −10° C., and

wherein the chemical composition satisfies the following formula, wherein the contents of Cr and Mo are expressed in weight %, Cr+Mo≤0.35.