US2016214177A1PendingUtilityA1
Corrosion and wear resistant cold work tool steel
Est. expiryOct 2, 2033(~7.2 yrs left)· nominal 20-yr term from priority
Inventors:Sebastian EjnermarkThomas HillskogLars EkmanRikard RobertssonVictoria BergqvistJenny KarlssonPetter DammUlrika MossfeldtRoland EdvinssonAnnika Engström SvenssonBerne Hogman
C23C 8/80C21D 1/18C22C 38/50B22F 3/15B22F 9/08C21D 6/005C22C 38/40B22F 2003/248C22C 38/001C22C 33/0285C22C 38/54C22C 38/22C21D 1/613C22C 38/24C22C 38/02C22C 38/48C22C 38/42B22F 2201/02C21D 6/002B22F 2301/35C22C 38/04C21D 9/0068C22C 38/46C21D 6/008B22F 3/24C22C 38/44C22C 38/52C23C 8/24C22C 38/60B22F 1/00B22F 1/0003C22C 38/30C22C 33/02
44
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Claims
Abstract
The invention relates to a corrosion and wear resistance cold work tool steel. The steel includes the following main components (in wt. %): C 0.3-0.8, N 1.0-2.2, (C+N) 1.3-2.2, C/N 0.17-0.50, Si≦1.0, Mn 0.2-2.0, Cr 13-30, Mo 0.5-3.0, V 2.0-5.0, balance optional elementals, iron and impurities.
Claims
exact text as granted — not AI-modified1 . A powder metallurgy manufactured steel consisting of (in weight %):
C
0.3-0.8
N
1.0-2.2
(C + N)
1.3-2.2
C/N
0.17-0.50
Si
≦1.0
Mn
0.2-2.0
Cr
13-30
Mo
0.5-3.0
W
≦1
(Mo + W/2)
0.5-3.0
V
2.0-5.0
Nb
≦2.0
(V + Nb/2)
2.0-5.0
(Ti + Zr + Al)
≦7.0
Ta
≦0.5
Co
≦10.0
Ni
≦5.0
Cu
≦3.0
Sn
≦0.3
B
≦0.01
Be
≦0.2
Bi
≦0.3
Se
≦0.3
Te
≦0.3
Mg
≦0.01
REM
≦0.2
Ca
≦0.05
S
≦0.5
balance iron and impurities.
2 . A powder metallurgy manufactured steel according to claim 1 , wherein the upper content of V is limited to at least one of 4.8%, 4.6%, 4.4%, 4.2% or 4.0%.
3 . A powder metallurgy manufactured steel according to claim 1 , wherein the steel fulfils at least one of the following (in weight %):
C
0.3-0.6
N
1.1-1.8
(C + N)
1.7-2.1
C/N
0.20-0.46
Cr
15-30
Mo
0.7-2.5
V
2.5-4.5
Nb
≦0.5
4 . A powder metallurgy manufactured steel according to claim 1 , wherein the steel fulfils at least one of the following (in weight %):
C
0.35-0.45
N
1.3-1.7
(C + N)
1.8-2.0
C/N
0.22-0.45
Cr
16-28
Mo
0.8-2.0
V
2.5-3.8
Co
4.0-6.0
Nb
≦0.1
Cu
0.02-2.0
5 . A powder metallurgy manufactured steel according to claim 1 , wherein the steel fulfils at least one of the following (in weight %):
Cr
18-26
Mo
0.8-1.5
Se
<0.05
Cu
0.05-1.5
Co
≦0.2
W
≦0.2
Ti
≦0.1
Nb
≦0.05
REM
≦0.05
B
≦0.004
6 . A powder metallurgy manufactured steel according to claim 1 , wherein the microstructure comprises tempered martensite and hard phases consisting of at least one of MX, M 2 X, M 23 C 6 and M 7 C 3 and wherein the steel has a hardness of 58-64 HRC, preferably 60-62 HRC.
7 . A powder metallurgy manufactured steel according to claim 1 , wherein the content of the hard phases MX, M 2 X, M 23 C 6 and M 7 C 3 fulfil the following requirements (in volume %):
MX
5-25
preferably
5-20
more preferably
5-15
M 2 X
≦10
preferably
≦5
more preferably
≦1
M 23 C 6 + M 7 C 3
≦10
preferably
≦5
more preferably
≦1
wherein M is at least one of V, Mo and Cr and X is at least one of C, N or B.
8 . A powder metallurgy manufactured steel according to claim 1 , wherein the steel at an austenitising temperature (T A ) of 1080° C. has a calculated PRE≧18 wherein PRE=Cr+3.3 Mo+30 N and Cr, Mo and N are the calculated equilibrium contents dissolved in the matrix at T A , wherein the chromium content dissolved in the austenite is at least 13%.
9 . A powder metallurgy manufactured steel according to claim 1 , wherein the steel at an austenitising temperature (T A ) of 1080° C. has a calculated PRE≧20 wherein PRE=Cr+3.3 Mo+30 N and Cr, Mo and N are the calculated equilibrium contents dissolved in the matrix at T A , wherein the chromium content dissolved in the austenite is at least 16%.
10 . A powder metallurgy manufactured steel according to claim 1 , wherein the steel at an austenitising temperature (T A ) of 1080° C. has a calculated PRE≧22 wherein PRE=Cr+3.3 Mo+30 N and Cr, Mo and N are the calculated equilibrium contents dissolved in the matrix at T A .
11 . A powder metallurgy manufactured steel according to claim 1 , wherein the steel at an austenitising temperature (T A ) of 1080° C. has a calculated PRE≧25 wherein PRE=Cr+3.3 Mo+30 N and Cr, Mo and N are the calculated equilibrium contents dissolved in the matrix at T A .
12 . A method of producing a steel having a composition as defined in claim 1 comprising:
atomizing a steel alloy having a chemical composition as defined in claim 1 apart from the nitrogen content,
subjecting powder to a nitrogenation treatment in order to adjust the nitrogen content of the alloy to the content defined in claim 1 ,
filling the powder into a capsule and subjecting the capsule to a HIP-treatment,
forming the obtained steel, and
subjecting the obtained steel to hardening and tempering.
13 . A method of producing a steel according to claim 12 , further comprising:
hardening the obtained steel at 950-1200° C., preferably at 1080-1150° C. for 30 min, deep cooling the hardened steel in liquid nitrogen, and tempering twice at 180-250° C., preferably at 200±10° C., for 2 hours.
14 . A method of producing a steel according to claim 12 , further comprising:
hardening the obtained steel at 950-1200° C., preferably at 1080-1150° C. for 30 min, deep cooling the hardened steel in liquid nitrogen, and tempering twice at 450-550° C., preferably at 500±10° C., for 2 hours.Cited by (0)
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