Continuous casting of Steel involves a complex, highly
technical and controlled process where molten metal is poured vertically into
an open bottomed mould and through sets of rolls within the caster. Products
include, rods, bars, sections, billets, slabs, and blooms, and are classed as
unfinished, requiring further processing. Traditionally, steel was poured into closed
moulds to create ingots of specific shapes. Over the years, continuous casting
has evolved and become the norm for all global Steel producers allowing improve
yield, quality, and productivity.
How does the process
works?
A continuous slab caster consists of a mould with a defined
number of rolls placed within several segments below it. Typically, a slab
caster is curved progressively through 90 degrees from vertical at the top, to
horizontal at the bottom. A dummy bar chain, fitted with a dummy bar head is
fed into the caster. The dummy bar head is positioned at the based of the mould
to act as a plug and is held in place with drive rolls which hydraulically
pinch the chain.
Molten Steel is poured from a ladle into a reservoir called
a tundish. The tundish allows the molten steel to flow from a nozzle, in its
base, at a controlled rate into the mould. As the mould fills the dummy bar
head is withdrawn down the caster by the drive rolls at a controlled speed
matching the flow of the molten Steel from the nozzle. The molten Steel in the
mould starts to solidify and forms a thin, but solid skin allowing it to
support itself when it leaves the opening at the base of the mould. The Steel
product then enters idle (non-driven) rolls, accurately positioned to allow
support and dimensional accuracy of the cast product. At the same time water
sprays are positioned strategically to control the cooling and metallurgy of
the product.
As the dummy bar chain is drawn through the continuous
caster, the Steel continues to be poured with the product solidifying further
as it is drawn through segments of rolls. The dummy bar chain and head are
removed as they leave the final rolls at the bottom of the continuous caster. The
drive rolls continue to draw the product through the caster allowing it to be
‘continually cast’ with the product being cut to length as it exits the caster.
Issues with
continuous caster roll surfaces
In an increasingly competitive global market, ensuring the integrity
of continuous caster roll surfaces has become an essential requirement for the efficient
production of cast steel. To make the process more efficient and cost-effective,
caster roll surfaces must resist the harsh environments they operate within.
Premature wear, corrosion or loss of diameter on a roll surface severely limits
the productivity of a continuous caster. However, with investment in research
and development with our customers, Corewire Limited has a wide range of Weldclad
roll cladding compositions, which can be used to optimise roll performance in a
given environment and application. This allows customers to optimise roll life
in operation, decrease the frequency of caster downtime and increase continuous
caster efficiency and productivity.
Corewire are experienced in providing solutions for continuouscaster roll surface issues, for more information you can give them a call on
+44 (0) 1252 517 766.
