US 12,473,608 B2
Steel composition in accordance with API 5L PSL-2 specification for X-65 grade having enhanced hydrogen induced cracking (HIC) resistance, and method of manufacturing the steel thereof
Prashant Pathak, Jharkhand (IN); Saurabh Kundu, Jharkhand (IN); Basudev Bhattacharya, Jharkhand (IN); Subrata Mukherjee, Jharkhand (IN); Amar Nath Bhagat, Jharkhand (IN); Hrishikesh Shastri, Jharkhand (IN); and Badirujjaman Syed, Jharkhand (IN)
Assigned to TATA STEEL LIMITED, Jharkhand (IN)
Appl. No. 16/982,422
Filed by TATA STEEL LIMITED, Jharkhand (IN)
PCT Filed Oct. 1, 2018, PCT No. PCT/IB2018/057606
§ 371(c)(1), (2) Date Sep. 18, 2020,
PCT Pub. No. WO2019/180499, PCT Pub. Date Sep. 26, 2019.
Claims priority of application No. 201831010054 (IN), filed on Mar. 19, 2018.
Prior Publication US 2021/0054473 A1, Feb. 25, 2021
Int. Cl. C21D 9/08 (2006.01); C21D 6/00 (2006.01); C21D 8/10 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01)
CPC C21D 9/085 (2013.01) [C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/105 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A steel comprising:
carbon (C) at a concentration ranging from about 0.02 wt % to about 0.06 wt %; manganese (Mn) at a concentration ranging from about 0.7 wt % to about 1.0 wt %; niobium (Nb) at a concentration ranging from about 0.06 wt % to about 0.10 wt %; titanium (Ti) at a concentration ranging from about 0.015 wt % to about 0.025 wt %; aluminium (Al) at a concentration ranging from about 0.03 wt % to about 0.10 wt %; silicon (Si) at a concentration ranging from about 0.1 wt % to about 0.5 wt %; nitrogen (N) at a concentration ranging from about 0.0001 wt % to about 0.0060 wt %; sulphur (S) at a concentration ranging from about 0.0001 wt % to about 0.0020 wt %; and
phosphorus (P) at a concentration ranging from about 0.0001 wt % to about 0.015 wt %, as elements,
wherein vanadium (V), chromium (Cr), boron (B), copper (Cu), and molybdenum (Mo) are not present in the steel,
wherein the steel exhibits a crack length ratio (CLR) of less than 10%, a crack thickness ratio (CTR) of less than 5%, a crack sensitivity ratio (CSR) of less than 2%, and a ferrite potential of less than 0.85 or more than 1.05, wherein the CLR, the CSR and the CTR are measured according to National Association of Corrosion Engineers (NACE) standard TM0284-2005, and
wherein a structure of the steel consists of polygonal ferrite and at least one microstructure selected from the group consisting of a bainitic ferrite and an acicular ferrite microstructure.