Typical
Wear Resistance by Comparison
Rating Wear
resistance under controlled testing procedures by NATA
certified and approved experts, produced the above
typical results. They included tests for abrasion and
impact under both high and low stress conditions.
However any rating
is dependent on a number of variables, such as the type
of testing procedure adopted, the type of test carried
out (high stress abrasion, low stress abrasion), the
load applied in the test, speed variations, calibration
anomalies etc. Results “in the field” do vary
markedly according to the type of material, impact
loads, speed of flow, support structures, consistency of
flow and material, particle size, particle shape,
correct machinery calibrations and other criteria.
Hardfaced Wear
Plate has achieved results as high as 30:1 ratio over
mild steel and as low as 12.6:1 ratio.
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Hardfaced Wear Plate Chemical Analysis
A typical analysis
of Hardfaced Wear Plate is as follows:
(1)
Chromium
- 25 % to 30 %
(2)
Carbon
- 4.3 % to 5.1 %
(3)
Manganese
- 1.5 % to 2.1 %
(4)
Silicon
- 0.8 % to 1.2 %
Plus trace
elements of molybdenum, nickel, sulphur and phosphorous.
A variety of other
alloys may be added to the mixture, such as vanadium,
boron, nickel, molybdenum and niobium, to produce
special wear resistant plates for specific needs - (e.g.
high heat resistance, fine particle dust abrasion,
increased hardness and impact resistance and many
others.)
Hardfaced Wear
Plate ranges in hardness from 56 to 61 on the ROCKWELL C
hardness scale - (i.e. up to 670 BRINEL, or 720
Vickers). A typical undiluted hardness is 59
Rockwell C.
Hardness can vary
according to:
-
Where the
reading is taken i.e. near the surface of the hard
facing layer, in the centre or near the interface
with the mild steel base plate.
-
The thickness
of the hard facing overlay deposit.
-
The
quality/analysis of the raw materials used.
-
The carbide
structure achieved inherent in the method adopted to
lay down the hardfacing deposit.
Hardness can be
increased by adding other alloys to the hard facing
mixture. However, hardness in isolation, is not a true
indication of the wear resistance of an alloy.
Hardness is only
one guide as to the quality and effectiveness of the
wear plate. Many other factors need also to be
taken into consideration - such as the method of
deposition, the carbide structure achieved and the type
of industry and material i.e. application for which the
wear plate is required.
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Attaching
Hardfaced Wear Plate
Three of the most
common methods to attach CrC55 Wear Plate are:
 |
 |
 |
| Nelson
Studs |
Countersunk Insert |
Plug
Weld |
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Cutting
Plasma arc is the
preferred method, however, arc air and friction disc are
also effective.
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Cold Forming
Hardfaced can be
bent by either press brake or rolling (Wear surface
inside) to a diameter of 600mm.
To form Hardfaced
to smaller diameters (200mm min) it is recommended that
4mm on 8mm and 7mm on 10mm be used.
Forming Hardfaced
with the wear surface on the outside, a minimum of 1
metre diameter is recommended.
Forming should be
carried out at right angles to the weld runs.
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Welding
The low carbon
steel substrate of Hardfaced Wear Plate can be welded
using normal consumables for MMAW and GMAW for mild
steel.
The wear surface
has negligible yield strength; hence no structural
welding should be performed on this surface.
It is important
when weld preparation is carried out, that any dilution
from a structural weld into the hard facing will result
in carbon pick up and likely cracking of the weld.
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Industrial Application
