公开(公告)号：US20240011117A1

公开(公告)日：2024-01-11

申请号：US18267082

申请日：2021-12-01

Applicant: POSCO CO., LTD

Inventor： Jae-Hoon LEE ,  Young-Roc IM

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/00 ,  C21D8/02 ,  C23G1/00

CPC classification number: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0236 ,  C21D8/0226 ,  C21D8/0273 ,  C23G1/00 ,  C21D2211/002 ,  C21D2211/008 ,  C21D2211/001

Abstract: Provided is a steel sheet that may be used for automobile parts and the like, and to a steel sheet having an excellent balance of strength and ductility, an excellent balance of strength and hole expansion ratio, and an excellent yield ratio evaluation index, and a method for manufacturing the same. The steel sheet includes: by wt %, C: 0.1 to 0.25%, Si: 0.01 to 1.5%, Mn: 1.0 to 4.0%, Al: 0.01 to 1.5%, P: 0.15% or less, S: 0.03% or less, N: 0.03% or less, B: 0.0005 to 0.005%, a balance of Fe, and unavoidable impurities; and as microstructures, bainite, tempered martensite, fresh martensite, retained austenite and unavoidable structures.

公开(公告)号：US20230340633A1

公开(公告)日：2023-10-26

申请号：US18341672

申请日：2023-06-26

Applicant: POSCO CO., LTD

Inventor： Young-Roc IM ,  Jong-Chan PARK ,  Jai-Hyun KWAK ,  Min-Seo KOO

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C23C2/06 ,  C23C2/40

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C23C2/06 ,  C23C2/40 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/003 ,  C21D2211/005 ,  C21D2211/008

Abstract: Provided is a method of manufacturing a high-strength cold rolled steel sheet. The method includes: preparing a slab; heating the slab to 1,150° C. to 1,250° C.; finish hot rolling the heated slab within 900° C. to 980° C.; cooling the slab at an average cooling rate of 10° C./sec to 100° C./sec; winding the slab in 500° C. to 700° C.; cold rolling the slab at a cold-rolling reduction ratio of 30% to 60% to obtain a cold rolled steel sheet; continuously annealing the cold rolled steel sheet at Ae3+30° C. to Ae3+80° C.; primarily cooling the continuously annealed steel sheet at an average cooling rate of 10° C./s or less to 560° C. to 700° C. and secondarily cooling the steel sheet at an average cooling rate of 10° C./s or more to 270° C. to 330° C.; and reheating the cooled steel sheet at a temperature increase rate of 5° C./s or lower to a temperature in a range of 380° C. to 460° C.

公开(公告)号：US20250066870A1

公开(公告)日：2025-02-27

申请号：US18945501

申请日：2024-11-12

Applicant: POSCO CO., LTD

Inventor： Hang-Sik CHO ,  Young-Roc IM

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/22 ,  C22C38/28 ,  C22C38/32 ,  C23C2/04 ,  C23C2/40

Abstract: Provided is a method of manufacturing a cold-rolled steel sheet. The method includes: cold-rolling a steel material; applying nickel (Ni) powder on a surface of the cold-rolled steel material in a coating amount of 300 mg/m2; heating the steel material to completely transform the steel material to austenite; slowly cooling the heated steel material at a cooling rate of 5-12° C./s to a slow cooling termination temperature of 630-670° C., and maintaining the steel material at the slow cooling termination temperature for 10-90 seconds; rapidly cooling the slowly cooled and maintained steel material at a cooling rate of 7-30° C./s to a temperature range of a martensitic transformation termination temperature or higher and a martensitic transformation initiation temperature or lower; and maintaining the rapidly cooled steel material at a temperature higher than the martensitic transformation initiation temperature and the bainite transformation initiation temperature or lower for 300-600 seconds and partitioning the steel material.

公开(公告)号：US20240352551A1

公开(公告)日：2024-10-24

申请号：US18684593

申请日：2022-08-25

Applicant: POSCO CO., LTD

Inventor： Young-Roc IM ,  Sang-Ho UHM ,  Young-Ha KIM

IPC: C21D9/46 ,  C21D1/18 ,  C21D1/84 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D1/84 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/06 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: Provided is a cold-rolled steel sheet including: by weight %, C: 0.10 to 0.16%, Si: 0.3 to 0.8%, Al: 0.01 to 0.5%, Mn: 2.0 to 3.0%, Cr: 0.001 to 0.5%, Mo: 0.001 to 0.5%, B: 0.0001 to 0.001%, Nb: 0.001 to 0.05%, Ti: 0.001 to 0.05%, P: 0.04% or less (excluding 0%), S: 0.01% or less (excluding 0%), N: 0.01% or less (excluding 0%), a remainder of Fe, and other unavoidable impurities, as a microstructure, by area %, ferrite: 10% or less (excluding 0%), retained austenite: more than 1% to 5% or less, martensite: 25% or more but less than 50%, and bainite: 35% or more but less than 70%. An average size of martensite-austenite (MA) in the bainite is 0.35 to 0.55 μm.