Linepipe Steel With Enhanced Sulfide Stress Cracking Resistance

Abstract

The present disclosure relates to methods and treatments of linepipe steels that transport one or both of crude oil and natural gas. More particularly, the present disclosure relates to sulfide stress cracking resistance of carbon steels for use as linepipe in transporting crude oil and natural gas by alternative thermo-mechanically controlled and/or one or more additional heat treatment processes.

1 . A method comprising:
 heating a carbon steel composition to a first reheating temperature, the first reheating temperature being greater than about 1175° C.;   deforming the composition while the composition is at a temperature in the range of the reheating temperature and a finishing temperature of greater than about Ar3; and   quenching the composition into a formed carbon steel.   
     
     
         2 . The method of  claim 1 , further comprising maintaining stable the first reheating temperature for a length of time greater than about one minute. 
     
     
         3 . The method of  claim 1 , wherein the deforming comprises at least one hot rolling step. 
     
     
         4 . The method of  claim 3 , wherein the deforming comprises at least two hot rolling steps having an extended interpass duration therebetween. 
     
     
         5 . The method of  claim 1 , wherein the quenching comprises accelerated cooling. 
     
     
         6 . The method of  claim 1 , wherein after quenching, the formed carbon steel has a microstructure comprising lath bainite. 
     
     
         7 . The method of  claim 1 , wherein the formed carbon steel has a SSC arrest toughness (K ISSC ) of greater than about 35 ksi-in 0.5 . 
     
     
         8 . The method of  claim 1 , wherein the formed carbon steel has a SSC arrest toughness (K ISSC ) of greater than about 20 ksi-in 0.5 . 
     
     
         9 . The method of  claim 1 , further comprising, after the quenching, reheating the formed carbon steel to a second reheating temperature. 
     
     
         10 . The method of  claim 9 , further comprising quenching the formed carbon steel after reheating the composition to the second reheating temperature, and thereafter, reheating the formed carbon steel to a third reheating temperature. 
     
     
         11 . A formed carbon steel prepared according to a method comprising:
 heating a carbon steel composition to a first reheating temperature, the first reheating temperature being greater than about 1175° C.;   deforming the composition while the composition is at a temperature in the range of the reheating temperature and a finishing temperature of greater than about Ar3; and   quenching the composition.   
     
     
         12 . The formed carbon steel of  claim 11 , further comprising maintaining stable the first reheating temperature for a length of time greater than about one minute. 
     
     
         13 . The formed carbon steel of  claim 11 , wherein the deforming comprises at least one hot rolling step. 
     
     
         14 . The formed carbon steel of  claim 13 , wherein the deforming comprises at least two hot rolling steps having an extended interpass duration therebetween. 
     
     
         15 . The formed carbon steel of  claim 11 , wherein the quenching comprises accelerated cooling. 
     
     
         16 . The formed carbon steel of  claim 11 , wherein after quenching, the formed carbon steel has a microstructure comprising lath bainite. 
     
     
         17 . The formed carbon steel of  claim 11 , wherein the formed carbon steel has a SSC arrest toughness (K ISSC ) of greater than about 35 ksi-in 0.5 . 
     
     
         18 . The formed carbon of  claim 11 , wherein the formed carbon steel has a SSC arrest toughness (K ISSC ) of greater than about 20 ksi-in 0.5 . 
     
     
         19 . The formed carbon steel of  claim 11 , further comprising, after the quenching, reheating the composition to a second reheating temperature. 
     
     
         20 . The formed carbon steel of  claim 19 , wherein the second reheating temperature is in the range of about (Acl−300° C.) to about Ad. 
     
     
         21 . The formed carbon steel of  claim 19 , further comprising maintaining stable the second reheating temperature for a length of time greater than about one minute. 
     
     
         22 . The formed carbon steel of  claim 19 , further comprising, before the second reheating, interim austenitizing the composition at an interim austenitizing temperature and, thereafter, quenching the composition after the interim austenitizing. 
     
     
         23 . The formed carbon steel of  claim 22 , wherein the interim austenitizing temperature is in the range of (Ac3+50° C.) to about (Ac3+200° C.). 
     
     
         24 . A method comprising:
 forming a formed carbon steel; and   thereafter, reheating the formed carbon steel to a reheating temperature.   
     
     
         25 . The method of  claim 24 , wherein the preparing is by a thermo-mechanically controlled process wherein the reheating temperature is in the range of about (Acl−300° C.) to about Acl. 
     
     
         26 . (canceled)