STEEL COMPOSITIONS HAVING IMPROVED ANTI-COKING PROPERTIES
Special usage steels, particularly those intended to be in contact with combustion fumes, are described. Tubular components produced based on such steels are also described. The steel both is resistant to the coking phenomenon and has improved mechanical performances. The steel contains no more than 0.15% carbon, from 0.3 to 1% manganese, from 1.4 to 3% silicon, from 0.5 to 3% copper, from 8 to 10% chrome, from 0.5 to 3% nickel, from 0.01 to 0.07% nitrogen, from 0.8 to 1.1% molybdenum, with the remainder being iron and impurities.
1 . A steel composition, comprising in percentage by weight:
no more than 0.15% carbon,
from 0.3 to 1% manganese,
from 1.4 to 3% silicon,
from 0.5 to 3% copper,
from 8 to 10% chrome,
from 0.5 to 3% nickel,
from 0.01 to 0.07% nitrogen,
from 0.8 to 1.1% molybdenum, and
iron.
2 . The steel composition according to claim 1 , further comprising:
no more than 0.04% aluminum,
no more than 0.025% phosphorus,
no more than 0.02% sulfur,
no more than 0.02% titanium,
no more than 0.05% niobium,
no more than 0.05% vanadium,
no more than 0.1% tungsten, and
no more than 0.05% cobalt.
3 . The steel composition according to claim 2 , wherein the content by weight of each of aluminum, phosphorus, sulfur, titanium, niobium, vanadium, tungsten, and cobalt does not exceed 0.01%.
4 . The steel composition according to claim 1 , comprising: from 0.08% to 0.15% of carbon.
5 . The steel composition according to claim 1 , comprising: from 0.09% to 0.11% of carbon.
6 . The steel composition according to claim 1 , comprising: from 1.5% to 2.5% of silicon.
7 . The steel composition according to claim 1 , comprising: from 0.5% to 2% of copper.
8 . The steel composition according to claim 1 , comprising: from 0.5% to 2.7% of nickel.
9 . The steel composition according to claim 1 , comprising: from 0.4% to 0.8% of manganese.
10 . The steel composition according to claim 1 , comprising: from 0.02% to 0.05% of nitrogen.
11 . The steel composition according to claim 2 , comprising: from 0.005% to 0.03% of aluminum.
12 . The steel composition according to claim 1 , further comprising:
no more than 0.025% phosphorus,
no more than 0.02% sulfur,
no more than 0.02% titanium,
no more than 0.05% niobium,
no more than 0.05% vanadium,
no more than 0.1% tungsten, and
no more than 0.05% cobalt.
13 . The steel composition according to claim 1 , further comprising: phosphorus and sulfur as impurities.
14 . The steel composition according to claim 1 , wherein the percentages by weight of silicon [Si], copper [Cu], and nickel [Ni] satisfy the following inequalities:
[Si]<1.5*(0.3[Cu]+[Ni]) for [Si]<2.5%;
2*[Si]<1.5*(0.3[Cu]+[Ni]) for [Si]≥2.5%;
and
[Cu]<[Ni].
15 . A tubular component, at least one part of which comprises:
the steel composition according to claim 1 .
16 . The tubular component according to claim 15 , wherein the at least one part is designed to be placed in contact with atmosphere containing coke.