2. What is STEEL ALLOY?
Steel is an alloy that consists mostly of iron and has a
carbon content between 0.2% and 2.1% by weight,
depending on the grade. Carbon is the most common
alloying material for iron, but various other alloying
elements are used, such as manganese, chromium,
vanadium, and tungsten.[1] Carbon and other elements
act as a hardening agent, preventing dislocations in
the iron atom crystal lattice from sliding past one
another. Varying the amount of alloying elements and
the form of their presence in the steel (solute
elements, precipitated phase) controls qualities such
as the hardness, ductility, and tensile strength of the
resulting steel. Steel with increased carbon content
can be made harder and stronger than iron, but such
steel is also less ductile than iron.
3. Alloys with a higher than 2.1% carbon content
are known as cast iron because of their lower
melting point and good castability.[1] Steel is
also distinguishable from wrought iron, which
can contain a small amount of carbon, but it is
included in the form of slag inclusions. Two
distinguishing factors are steel's increased rust
resistance and better weldability.
4. Though steel had been produced by various
inefficient methods long before the Renaissance, its
use became more common after more-efficient
production methods were devised in the 17th
century. With the invention of the Bessemer process
in the mid-19th century, steel became an
inexpensive mass-produced material. Further
refinements in the process, such as basic oxygen
steelmaking (BOS), lowered the cost of production
while increasing the quality of the metal. Today,
steel is one of the most common materials in the
world, with more than 1.3 billion tons produced
annually. It is a major component in buildings,
infrastructure, tools, ships, automobiles, machines,
appliances, and weapons. Modern steel is generally
identified by various grades defined by assorted
5. STAINLESS STEEL
Stainless steels are distinguished from other
steels by a minimum chromium content of
10.5%, which makes them more resistant to
corrosive aqueous environments and to
oxidation. Although there are exceptions,
stainless steel castings are classified as
"corrosion resistant" when used in aqueous
environments and vapors below 1200°F (650°C)
and "heat resistant" when used above this
temperature.
6. The usual distinction between the heat and
corrosion resistant casting grades is carbon
content. For a stainless steel casting to perform
well in a corrosive environment, the carbon
content must be low. Heat resistant grades have
higher carbon contents to improve elevated
temperature strength
7. WHY TO MIX OTHER
ELEMENTS??
Chromium, nickel, and molybdenum are
the primary alloying elements that
determine the structure, mechanical
properties, and corrosion resistance of
steel
8. Nickel and chromium have the greatest
influence on heat resistant castings.
Intentional additions of less than 1
%carbon, nitrogen, niobium, tantalum,
titanium, sulfur, and slightly larger
additions of copper, manganese, silicon,
and aluminum are used to modify
properties. Some minor elements can
have a positive or negative effect on
properties depending on the application.
26. Roll Forming & Welding
The first stage of the manufacturing process is
roll forming along with a state-of-art welding
technology. The TIG welding method uses
electricity to obtain fusion. The heat-affected
zone following TIG welding maintains good
mechnical and corrosion-resistance properties
than other traditional welding methods.
28. Pickling
Corrosion and an incorrect roughness on the
internal surface of the tubes could cause a
problem for the end user. The Pickling process is
carried out in a bath of acid solution so as to
remove every trace of ferrous & oxidizing
contamination. APT is able to pickle tubes in
lengths of up to 10 meters.
29. Solution Annealing
The solution annealing process, eliminates the
work hardening effect caused by cold working, and
also homogenizes the structure of the welded area
enhancing corrosion resistance. The different
stages of heat treatment are carried out and the
duration and speed of the tubes, are constantly
monitored in order to achieve a correct
solubilization.
30. Polishing
Pipes & Tubes can be supplied with outer
polished surface of Grit 120 to Grit 600 or
mirror polished surface.