Ferritic stainless steel with improved grain boundary erosion, and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-2024026507-A1
Application number	US-202118265167-A
Country	US
Kind code	A1
Filing date	Oct 29, 2021
Priority date	Dec 3, 2020
Publication date	Jan 25, 2024
Grant date	—

Abstract

Disclosed is a ferritic stainless steel with reduced grain boundary erosion. A ferritic stainless steel with reduced grain boundary erosion according to an embodiment includes, in percent by weight (wt %), 0.005 to 0.1% of C, 0.01 to 1.0% of Si, 0.01 to 1.5% of Mn, 13 to 18% of Cr, 0.005 to 0.1% of N, 0.005 to 0.2% of Al, 0.005 to 0.1% of Ni, 0.003% or less of Mo, 0.05% or less of P, 0.005% or less of S, and the remainder being Fe and impurities, and satisfies an Acl, defined by Formula (1) below, of 900 or more and 990 or less:Ac1=36Cr+90Si+76Mo+760Al+350−(800C+1300N+150Ni+50Mn)  Formula (1):(wherein C, N, Si, Mn, Cr, Ni, Al, Mn, and Mo represent a content (wt %) of each element).

First claim

1 . A ferritic stainless steel with reduced grain boundary erosion comprising, in percent by weight (wt %), 0.005 to 0.1% of C, 0.01 to 1.0% of Si, 0.01 to 1.5% of Mn, 13 to 18% of Cr, 0.005 to 0.1% of N, 0.005 to 0.2% of Al, 0.005 to 0.1% of Ni, 0.003% or less of Mo, 0.05% or less of P, 0.005% or less of S, and the remainder being Fe and impurities,
wherein an Ac1, defined by Formula (1) below, is 900 or more and 990 or less:
Ac1=36Cr+90Si+76Mo+760Al+350−(800C+1300N+150Ni+50Mn)  Formula (1):

(wherein C, N, Si, Mn, Cr, Ni, Al, Mn, and Mo represent a content (wt %) of each element).

2 . The ferritic stainless steel according to claim 1 , wherein the ferritic stainless steel comprises, in percent by weight (wt %), 0.4 to 1.0% of Mn and 0.1 to 0.15% of Al.

3 . A method of manufacturing a ferritic stainless steel with reduced grain boundary erosion, the method comprising:
preparing a slab comprising, in percent by weight (wt %), 0.005 to 0.1% of C, 0.01 to 1.0% of Si, 0.01 to 1.5% of Mn, 13 to 18% of Cr, 0.005 to 0.1% of N, 0.005 to 0.2% of Al, 0.005 to 0.1% of Ni, 0.003% or less of Mo, 0.05% or less of P, 0.005% or less of S, and the remainder being Fe and impurities, and satisfying an Ac1, defined by Formula (1) below, of 900 or more and 990 or less; reheating the slab; rough-rolling the reheated slab and finish-rolling the rough-rolled steel material; coiling the hot-rolled steel material; continuous annealing the coiled steel material in a temperature range T(A) defined by Formula (2) below; and acid-pickling the continuous annealed steel material,
Ac1=36Cr+90Si+76Mo+760Al+350−(800C+1300N+150Ni+50Mn)  Formula (1):

(wherein C, N, Si, Mn, Cr, Ni, Al, Mn, and Mo represent a content (wt %) of each element)
870° C.≤T(A)≤(Ac1-10)° C.  Formula (2):

4 . The method according to claim 3 , wherein the slab comprises, in percent by weight (wt %), 0.4 to 1.0% of Mn and 0.1 to 0.15% of Al.

5 . The method according to claim 3 , wherein the reheating is performed in a temperature range of 1,000 to 1,200° C.

6 . The method according to claim 3 , wherein the finish rolling is performed in a temperature range of 800 to (Ac1-10)° C.

7 . The method according to claim 3 , wherein the coiling is performed in a temperature range of 750 to (Ac1-10)° C.

8 . The method according to claim 3 , wherein the continuous annealing is performed for 3 to 10 minutes.

Assignees

• Posco Co Ltd

Inventors

• Park Soo-Ho
• Kim Dong-Hoon
• Park Jae-Seok
• Kim Youngjun

Classifications

• C21D8/02

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

• C21D6/004

  containing Cr and Ni · CPC title

• C21D8/0247

  characterised by the heat treatment · CPC title

• C22C38/44 Primary

  with molybdenum or tungsten · CPC title

• C22C38/02

  containing silicon · CPC title