Qt heat treated high carbon hot rolled steel sheet, high carbon cold rolled steel sheet, qt heat treated high carbon cold rolled steel sheet, and manufacturing methods thereof

Patent metadata

Field	Value
Publication number	US-2024076766-A1
Application number	US-202118268511-A
Country	US
Kind code	A1
Filing date	Dec 10, 2021
Priority date	Dec 21, 2020
Publication date	Mar 7, 2024
Grant date	—

Abstract

Provided are a QT heat treated high carbon hot rolled steel sheet, a high carbon cold rolled steel sheet, a QT heat treated high carbon cold rolled steel sheet, and manufacturing methods thereof, wherein the QT heat treated high carbon hot rolled steel sheet comprises, in weight %, C: 1.0-1.4%, Si: 0.1-0.4%, Mn: 0.1-0.8%, Cr: 0.3-11%, W: 0.05-2.5%, P: 0.03% or less, S: 0.03% or less, Al: 0.02% or less, and the balance being Fe and other inevitable impurities, the average size of carbides being 0.1-20 μm.

First claim

1 . A QT heat treated high carbon hot rolled steel sheet, comprising:
in weight %, C: 1.0 to 1.4%, Si: 0.1 to 0.4%, Mn: 0.1 to 0.8%, Cr: 0.3 to 11%, W: 0.05 to 2.5%, P: 0.03% or less, S: 0.03% or less, Al: 0.02% or less, and a balance of Fe and other inevitable impurities, wherein a microstructure contains, in area %, carbide: 0.1 to 20% and the balance being tempered martensite, and an average size of the carbide is 0.1 to 20 μm.

2 . The QT heat treated high carbon hot rolled steel sheet of claim 1 , wherein the hot-rolled steel sheet further includes one or more selected from the group consisting of V: 0.8% or less (excluding 0%), Mo: 2.5% or less (excluding 0%), and Nb: 1.5% or less (excluding 0%).

3 . The QT heat treated high carbon hot rolled steel sheet of claim 1 , wherein the hot-rolled steel sheet has a hardness of 350 Hv or more.

4 . The QT heat treated high carbon hot rolled steel sheet of claim 1 , wherein the hot-rolled steel sheet has a wear reduction of 35 mg or less when a reheating temperature before QT is 800° C., a wear reduction of 27 mg or less when the reheating temperature before QT is 850° C., and a wear reduction of 25 mg or less when the reheating temperature before QT is 900° C.

5 . A high carbon cold rolled steel sheet, comprising:
in weight %, C: 1.0 to 1.4%, Si: 0.1 to 0.4%, Mn: 0.1 to 0.8%, Cr: 0.3 to 11%, W: 0.05 to 2.5%, P: 0.03% or less, S: 0.03% or less, Al: 0.02% or less, and a balance of Fe and other inevitable impurities, wherein a microstructure includes, in area %, ferrite: 20 to 99.9%, cementite: 10% or less, pearlite: 50% or less, and carbide: 0.1 to 20%, and an average size of the carbide is 0.1 to 20 μm.

6 . The high carbon cold rolled steel sheet of claim 5 , wherein the cold-rolled steel sheet further includes one or more selected from the group consisting of V: 0.8% or less (excluding 0%), Mo: 2.5% or less (excluding 0%), and Nb: 1.5% or less (excluding 0%).

7 . The high carbon cold rolled steel sheet of claim 5 , wherein the cold-rolled steel sheet has a hardness of 350 Hv or less.

8 . A QT heat treated high carbon cold rolled steel sheet, comprising:
in weight %, C: 1.0 to 1.4%, Si: 0.1 to 0.4%, Mn: 0.1 to 0.8%, Cr: 0.3 to 11%, W: 0.05 to 2.5%, P: 0.03% or less, S: 0.03% or less, Al: 0.02% or less, and a balance of Fe and other inevitable impurities, wherein a microstructure contains, in area %, carbide: 0.1 to 20% and the balance being tempered martensite, and an average size of the carbide is 0.1 to 20 μm.

9 . The QT heat treated high carbon cold rolled steel sheet of claim 8 , wherein the cold-rolled steel sheet further includes one or more selected from the group consisting of V: 0.8% or less (excluding 0%), Mo: 2.5% or less (excluding 0%), and Nb: 1.5% or less (excluding 0%).

10 . The QT heat treated high carbon cold rolled steel sheet of claim 8 , wherein the cold-rolled steel sheet has a hardness of 350 Hv or more.

11 . The QT heat treated high carbon cold rolled steel sheet of claim 8 , wherein the cold-rolled steel sheet has a wear reduction of 25 mg or less when the reheating temperature before QT is 900° C.

12 - 25 . (canceled)

Assignees

• Posco Co Ltd

Inventors

• Kim Sun-Mi
• Choi Jae-Hun
• Kim Hak-Jun

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C22C38/26 Primary

  with niobium or tantalum · CPC title

• C21D1/18

  Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62) · CPC title

• C21D1/32

  Soft annealing, e.g. spheroidising · CPC title

• C21D6/002

  containing Cr (C21D6/004 takes precedence) · CPC title