Hardened nickel-chromium-titanium-aluminum alloy with good wear resistance, creep resistance, corrosion resistance and workability
Hardened nickel-chromium-titanium-aluminum wrought alloy contains, (in mass %) 5-35% chromium, 1.0-3.0% titanium, 0.6-2.0% aluminum, 0.005-0.10% carbon, 0.0005-0.050% nitrogen, 0.0005-0.030% phosphorus, max. of each (next eleven) 0.010% sulfur 0.020% oxygen 0.70% silicon 2.0% manganese 0.05% magnesium 0.05% calcium 2.0% molybdenum 2.0% tungsten 0.5% niobium 0.5% copper 0.5% vanadium, 0-20% Fe, 0-15% cobalt, 0-0.20% Zr, 0.0001-0.008% boron, the remainder nickel and usual impurities. The nickel content is greater than 35%. Cr+Fe+Co≥26% fh≥0 fh=6.49+3.88 Ti+1.36 Al−0.301 Fe+(0.759−0.0209 Co) Co−0.428 Cr−28.2 C.
1. A valve comprising an age-hardening nickel-chromium-titanium-aluminum wrought alloy, with (in mass-%)
28 to 31% chromium,
1.5 to 3.0% titanium,
1.5 to 2.0% aluminum,
0.005 to 0.10% carbon,
0.0005 to 0.050% nitrogen,
0.0005 to 0.030% phosphorus,
max. 0.010% sulfur,
max. 0.020% oxygen,
max. 0.70% silicon,
max. 2.0% manganese,
max. 0.05% magnesium,
max. 0.05% calcium,
0.01 to 0.04% molybdenum,
0.01 to 0.04% tungsten,
max. 0.1% niobium,
<0.015% copper,
max. 0.5% vanadium,
>3 to 20% Fe,
2 to 12% cobalt,
if necessary 0 to 0.20% Zr,
if necessary 0.0001 to 0.008% boron,
the rest nickel and the usual process-related impurities,
wherein the nickel content is greater than 35% and the following relationships must be satisfied:
Cr+Fe+Co>33% (1)
and
fh> 0 with (2a)
fh= 6.49+3.88Ti+1.36Al−0.301Fe+(0.759−0.0209Co)Co−0.428Cr−28.2C (2)
wherein Ti, Al, Fe, Co, Cr and C are the concentrations of the elements in question in mass-% and fh is expressed in %; and
fver=≤ 7 with (3a)
fver= 32.77+0.5932Cr+0.3642Mo+0.513W+(0.3123−0.0076Fe)Fe+(0.3351−0.003745Co−0.0109Fe)Co+40.67Ti*Al+33.28Al 2 −13.6TiAl 2 −22.99Ti−92.7Al+2.94Nb (3)
wherein Cr, Mo, W, Fe, Co, Ti, Al and Nb are the concentrations of the elements in question in mass-% and fver is expressed in %; and
wherein the valve has a specific gross change in mass of less than 9.26 g/m 2 after an oxidation test at 800° C. in air after 576 hours.
2. The valve according to claim 1 , wherein the alloy has a carbon content of 0.01 to 0.10%.
3. The valve according to claim 1 , wherein the alloy contains an iron content of >3 to 15.0%.
4. The valve according to claim 1 , wherein the alloy has a content of boron of 0.0005 to 0.006%.
5. The valve according to claim 1 , in which the nickel content of the alloy is greater than 40%.
6. The valve according to claim 1 , in which the nickel content of the alloy is greater than 45%.
7. The valve according to claim 1 , in which the nickel content of the alloy is greater than 50%.
8. The valve according to claim 1 , wherein
Cr+Fe+Co≥48.6% (1a)
wherein Cr, Fe and Co are the concentrations of the elements in question in mass-%.
9. The valve according to claim 1 , wherein
fh≥ 1 with (2b)
fh= 6.49+3.88Ti+1.36Al−0.301Fe+(0.759−0.0209Co)Co−0.428Cr−28.2C (2)
wherein Ti, Al, Cr, Fe, Co and C are the concentrations of the elements in question in mass-% and fh is expressed in %.
10. The valve according to claim 1 , wherein optionally the following elements may also be present in the alloy:
Y 0-0.20% and/or
La 0-0.20% and/or
Ce 0-0.20% and/or
Ce mixed metal 0-0.20% and/or
Hf 0-0.20% and/or
Ta 0-0.60%.
11. The valve according to claim 1 , wherein the impurities are adjusted in contents of max. 0.002% Pb, max. 0.002% Zn, max. 0.002% Sn.