Titanium-free alloy
Titanium-free alloy which has great resistance to pitting and crevice corrosion and a high yield point in the strain-hardened state and includes (in wt %) a maximum of 0.02% C, a maximum of 0.01% S, a maximum of 0.03% N, 20.0-23.0% Cr, 39.0-44.0% Ni, 0.4-<1.0% Mn, 0.1-<0.5% Si, >4.0-<7.0% Mo, a maximum of 0.15% Nb, >1.5-<2.5% Cu, 0.05-<0.3% Al, a maximum of 0.5% Co, 0.001-<0.005% B, 0.005-<0.015% Mg, the remainder consisting of Fe and smelting-related impurities.
1. A process for the manufacture of a titanium-free alloy with pitting and crevice corrosion resistance as well as offset yield strength in the cold-worked condition, with the following composition in weight %:
C
max. 0.02%
S
max. 0.01%
N
max. 0.03%
Cr
20.0-23.0%
Ni
39.0-44.0%
Mn
0.4-<1.0%
Si
0.1-<0.5%
Mo
>4.0-<7.0%
Nb
max. 0.15%
Cu
>1.5-<2.5%
Al
0.05-<0.3%
Co
max. 0.5%
B
0.001-<0.005%
Mg
0.005-<0.015%
V
0.2-0.7%
Fe
the rest as well as melting-related impurities
wherein
a) the alloy is melted openly in continuous or ingot casting,
b) to eliminate the segregations caused by the increased molybdenum content, a homogenizing annealing of the produced blooms/billets is performed at 1150-1250° C. for 15 to 25 h, wherein
c) the homogenizing annealing is performed in particular following a first hot forming.
2. The process according to claim 1 wherein the alloy has the following composition in weight %:
C
max. 0.015%
S
max. 0.005%
N
max. 0.02%
Cr
21.0-<23%
Ni
>39.0-<43.0%
Mn
0.5-0.9%
Si
0.2-<0.5%
Mo
>4.5-6.5%
Nb
max. 0.15%
Cu
>1.6-<2.3%
Al
0.06-<0.25%
Co
max. 0.5%
B
0.002-0.004%
Mg
0.006-0.015%
V
0.2-0.7%
Fe
the rest as well as melting-related impurities.
3. The process according to claim 1 wherein the alloy has the following composition in weight %:
Cr
21.5-<23%
Ni
>39.0-<42%
Mn
0.4-<1.0%
Si
0.2-<0.5%
Mo
>5-<6.5%
Cu
>1.6-<2.2%
Al
0.05-<0.3%
B
0.001-<0.005%
Mg
0.005-0.015%
V
0.2-0.7%
Fe
the rest as well as melting-related impurities.