Patent ID: 11932926
Assignee: OUTOKUMPU OYJ
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A duplex ferritic austenitic stainless steel utilizing a transformation induced plasticity (TRIP) effect and containing:
less than 0.04 weight % carbon,
0.2-0.8 weight % silicon,
0.3-2.0 weight % manganese,
14.0-17.6 weight % chromium,
2.0-5.0 weight % nickel,
4.0-7.0 weight % molybdenum,
less than 4.5 weight % tungsten,
0.1-1.5 weight % copper,
0.14-0.23 weight % nitrogen,
more than 0% and up to 0.05% magnesium, and
the rest being iron and inevitable impurities occurring in stainless steels, and wherein a co-effect of the chromium, molybdenum and tungsten contents in weight % is in the range of 20<(Cr+Mo+0.5W)<23.5, where the ratio Cr/(Mo+0.5W) is in the range of 2-4.75, and the pitting resistance equivalent value (PRE) is in the range of 35-42,
wherein the PRE is calculated according to the following formula:

PRE=% Cr+3.3(% Mo+0.5% W)+30(% N)−% Mn, and

wherein the inevitable impurities comprise less than 0.010 weight % S, and less than 0.040 weight % P so that the sum (S+P) is less than 0.04 weight %.