Ferritic stainless steel and use thereof in the manufacture for high temperature resistant products
Abstract
Ferritic stainless steel, comprising the following Chemical elements expressed in percentage by weight: —Cr 14.0-20.0 —Al 0.50-1.50 —Zr 0.10-0.50 —Si 0.30-1.50 —Ti 0.10-0.35 —Nb 0.25-0.55 —C<0.035 —N<0.035 provided that the content of Ti, Nb, C and N satisfy the following relation: %Ti+%Nb/1.94>9 (%C+%N) and substantially iron q. s. to 100. This steel may also comprise Yttrium and/or rare earth elements in a percentage by weight comprised in the range 0.10-0.30. The invention also encompasses products manufacturable with the steel of the invention, in particular vehicle exhaust manifold systems. Figure (I) shows a cyclic oxidation test carried out at 1000° C. on samples having the composition of an embodiment of the steel according to the invention.
Claims
exact text as granted — not AI-modified1 . A ferritic stainless steel, which comprises the following chemical elements expressed in percentage by weight:
Cr
14.0-20.0
Al
0.50-1.50
Zr
0.10-0.50
Si
0.30-1.50
Ti
0.10-0.35
Nb
0.25-0.55
C
<0.035
N
<0.035
provided that the contents of Ti, Nb, C and N satisfy the following relation:
%Ti+%Nb/1.94>9 (%C+%N)
and substantially iron q.s. to 100.
2 . The ferritic stainless steel according to claim 1 , and further including Yttrium and/or rare earth elements in a percentage by weight comprised in the range 0.10-0.30.
3 . A steel strip or sheet, made of ferritic stainless steel according to claim 1 , which is weldable, formable, and highly resistant to oxidation and creep.
4 . A process for preparing the steel strip or sheet according to claim 3 , which comprises the following steps:
hot and/or cold rolling; annealing, after hot and/or cold rolling, at a temperature ranging from 900° to 1200° C. and for times lower than 3600s; optional pickling after hot and/or cold rolling.
5 . (Cancelled)
6 . Flat blooms, strips, ingots, castings, forgings and semimanufactured items, made of steel according to claim 1 .
7 . (Cancelled)
8 . (Cancelled)
9 . Pipes and pipe-derivable products, manufactured with the strip or sheet according to claim 3 .
10 . The pipe-derivable product according to claim 9 , employed as a component of a high temperature exhaust system.
11 . The pipe derivable product according to claim 10 , employed as a manifold of a vehicle exhaust system.
12 . Weldless pipes, welded pipes or longitudinally welded pipes manufactured with the steel strip or sheet according to claim 3 .
13 . A steel strip or sheet, made of steel according to claim 2 , which is weldable, formable and highly resistant to oxidation and creep.
14 . A process for preparing the steel strip or sheet according to claim 13 , which comprises the following steps:
hot and/or cold rolling annealing, after hot and/or cold rolling, at a temperature ranging from 900° to 1200° C. and for times lower than 3600s; optional pickling after hot and/or cold rolling.
15 . Flat blooms, strips, ingots, castings, forgings and semimanufactured items made of steel according to claim 2.Join the waitlist — get patent alerts
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