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Heat Resistant Steel
Heat resistant steel is designed typically for
use in heat treat furnaces and heat exchangers -
high nickel and chrome steels. Typical parts
include heat treat trays, grids and hangers.
Duplex &
Super Duplex
Duplex & Super Duplex steels are a specification
and use of materials which combine corrosion
resistance with high mechanical strength is a
fundamental requirement. Duplex steels
introduced the use of a deliberate nitrogen
addition in order to improve ductility and
corrosion resistance. This class of steel offers
excellent castability, weldability and
machinability.
22%
chromium stainless steels provide better pitting
resistance and resistance to crevice corrosion
than type 316 stainless steel by virtue of a
more stable passive film and also have greater
mechanical strength. However, for optimum
corrosion resistance, a 25% chromium high alloy
duplex stainless steel is required and these
alloys are often referred to as super duplex
stainless.
Hastelloy
The predominant alloying ingredient is typically
the transition metal nickel. Other alloying
ingredients are added to nickel in each of the
subcategories include varying percentages of the
elements molybdenum, chromium, cobalt, iron,
copper, manganese, titanium, zirconium,
aluminum, carbon, and tungsten.
The
primary function of the Hastelloy super alloys
is that of effective survival under high
temperature, high stress service in a moderately
to severely corrosive, and/or erosion prone
environment where more common and less expensive
iron-based alloys would fail—including the
pressure vessels of some nuclear reactors,
chemical reactors, and pipes and valves in
chemical industry.
Inconel
Inconel alloys are oxidation and corrosion
resistant materials well suited for service in
extreme environments. Inconel retains strength
over a wide temperature range, attractive for
high temperature applications where aluminum and
steel would succumb to creep as a result of
thermally-induced crystal vacancies. Inconel's
high temperature strength is developed by solid
solution strengthening or precipitation
strengthening, depending on the alloy.
Inconel is often encountered in extreme
environments. It is common in gas turbine
blades, seals, and combustors, as well as
turbocharger rotors and seals, high temperature
fasteners, chemical processing and pressure
vessels, heat exchanger tubing, natural gas
processing with contaminants such as H2S and
CO2, firearm sound suppressor blast baffles, and
Formula One exhaust systems.
Austenitic Steels
Austenitic stainless steels have high ductility,
low yield stress and relatively high ultimate
tensile strength, when compare to typical carbon
steel.
Steels containing high percentages of certain
alloying elements such as manganese and nickel
which are austenitic at room temperature and
cannot be hardened by normal heat-treatment but
do work harden. They are also non-magnetic.
Typical examples of austenitic steels include
the 18/8 stainless steels and 14% manganese
steel.
Martensitic Steels
These grades of stainless have chromium in the
range of 11% to 17% as the sole major alloying
addition. This is the same as the ferritic
grades. However, carbon is added in amounts from
0.10 % to 0.65% to radically change the behavior
of the martensitic alloys. The high carbon
enables the material to be hardened by heat
treatment.
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