CORROSION AND ABRASION-RESISTANT ROLL FOR CONTINUOUS CASTING MACHINES

ROULEAU RESISTANT A LA CORROSION ET A L'ABRASION POUR MACHINES DE COULEE CONTINUE

English Abstract

ABSTRACT
A roller for continuous casting machines is of a basical-
ly drum-shaped configuration and has a cylindrical surface. The
roller has a ductile, corrosion-proof buffer layer on its surface,
of a thickness not exceeding about 0.1 mm, a melting point in
excess of 1000°C, and an elongation at fracture exceeding 10%. An
outer, corrosion- and abrasion-resistant layer covers the buffer
layer and has a greater thickness than the buffer layer. The
buffer layer is made of nickel or a nickel alloy, and is an
electrolytically deposited layer, the outer layer being of a
sintered configuration.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Roll or roller for continuous casting machines, being of
a basically drum-shaped configuration and having a cylindrical sur-
face, said roll comprising: a ductile, corrosion-proof buffer
layer on said surface, having a thickness not exceeding about 0.1
mm, a melting point in excess of 1000°C, and an elongation at
fracture exceeding 10%; and an outer, corrosion- and abrasion
resistant layer on top of the buffer layer and having greater
thickness than the buffer layer.
2. Roll or roller as in Claim 1, said buffer layer being
made of nickel or a nickel alloy.
3. Roll or roller as in Claim 1 or 2, the buffer layer
being an electrolytically deposited layer, the outer layer being
of a sintered configuration.

Description

BACKGROUND OF 111E LNVENTION
lhe present invention relates to a roll or roller o~ the type used
in roller -tracks for withdrawing a casting from a mold in a cantinuous
casting machine.
Rollers o~ the type to which the invention pertains experience
considerable wear and tear. Thus, the surface of such a roller must be as
abrasion-proof as possible. Even more important is that the rolls are
corrosion-proof due to their extensive exposure to water ~mder high tempera-
ture operating conditions. The roller itself and particularly the material10
used for its construction may not be adequate on all of these points. There-
fore, it is necessary to coat or jacket such a roller with a material that
provides better protection.
Accordingly, it is known to spray on a coating which protects the
roll against formation of stress cracks. The coating consists essentially of
metal and/or metal oxide. In order to improve the adhesive strength of the
coating, it should be sintered. However, one has employed only a pure
metallic material for this purpose.
It has been observed that under a heavy coatJ the coated roller may
bend and the sintered layer is prone to develop cracks in its crystal struc-
ture. These cracks are sooner or later penetrated by a corrosive medium,
e.g., the cooling water in the withdrawal path, and the substrate of the
roller body will begin to corrode which, in turn, will tend to delaminate the
protective layer, resulting in progressive localized, but expanding,
destruction.
DESCRIPTION OF ~ INVENTION
_ _ ___
It is an object of the present invention to improve rolls or
rollers for continuous casting machines ~y providing improved corrosion
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resistance.
The invention provides a roll or roller for continuous
casting machines, being of a basically drum-shaped configuration
and having a cylindrical surface, said roll comprising: a du~tile,
corrosion-proof bu~fer layer on said surface, having a thickness
not exceeding about 0.1 mm, a melting point in excess of 1000C,
and an elongation at fracture exceeding 10~; and an outer,
corrosion- and abrasion-resistant layer on top of the buffer layer
and having greater thickness than the buffer layer.
This arrangement can prevent delamination of the outer
wear-resistant and corrosion-proof layer of the roll, even in a
roll or rollers which may experience considerable bending stress.
The preferred embodiment of the invention and features
and advantages thereof will be better understood from the following
description taken in connection with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
... ...
The figure i5 a longitudinal section through a roller
coated in accordance with the preferred embodiment of the inven-
tion.
Proceeding now to the detailed description of the draw-
ings, the figure illustrates a roll or roller 1, being, for
example, constructed as shown in United States Letters Patent
4,086,957. Briefly, the roll has a cylindrical, tubular body
or member 11 to which are affixed two end pieces 12 and 13, serving
as journal members and being provided with axial inlets and outlets
for the passage of cooling fluid, e.g., water; ducts distribute the
cooling water to flow adjacent to the interior wall o~ tubular
member 11. Further details can be taken from the above-mentioned
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patent.
The outer, cylindrical surface of member 11 as well as
the surface portions of members 12 and 13 cylindrically aligned
with the outer surface of
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member ll, are coyered by a particular, highly ductile buffer layer 3. This
layer is preferably made of nichel or a nickel alloy and has a thickness not
exceeding 0.1 mm ~about 4 mils). Ihe melting point of the layer is, indeed,
in excess of 1000C, and the elongation at rupture exceeds 10%. This nickel
or nickel alloy layer is preferably electrolytically deposited on roll 1.
A regular, corrosion-resistant and abrasion-resistant layer 2 is
placed on buffer layer 3. This layer 3 is preferably made of pure Ni
(99,9 % Ni), having, for example, a thickness of 0,05 mm. Layer 2 is pre-
ferably sintered onto buffer layer 3. and has a composition for example of
74,5 % Ni, 17,0 % C, 4 % Si, 4 % B and 0,5 % C.
Buffer layer 3 has a higher ductility than outer layer 2. Thus,
even under heavy bending, strain cracks will not develop in layer 3; cracks
may develop in layer 2, but even if moisture penetrates these cracks, buffer
layer 3 is not amenable to corrosion and, thus, neither layer will delaminate.
The body, 1, remains well protected against corrosion and abrasion.
The invention is not limited to the embodiment described above, but
all changes and modifications thereof not constituting departures from the
spirit and scope of the invention are intended to be included.