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 Properties
of Mitsubishi carbide
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Relationship between cobalt content
and hardness |
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Relationship between cobalt content
and strength |
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Strength vs. Hardness |
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Toughness vs. Hardness |
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 Strength |
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Hardmetals -- Determination of transverse rupture strength:
ISO 3327
The strength of cemented carbide is measured by the transverse rapture
strength test (TRS), which is a simple three-point bending test. The
TRS value indicates the relative strength of the tools. The TRS test
is also an indicator of the quality level of the product. As cemented
carbide is a relatively brittle material, its strength is strongly
affected by inherent flaws and defects. Thus both the mean TRS value
and the standard deviation of values of the TRS value ca also be used
a guide to quality and performance.
The TRS value of a cemented carbide can be increased by increasing
the binder content. |
| Hardness |
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Hardmetals -- Vickers hardness test: ISO 3878
Hardmetals -- Rockwell hardness test (scale A): ISO 3738
The hardness of cemented carbides is generally measured on the Rockwell
A scale and shown as HRA. The hardness value indicates the wear resistance
properties of a tool In general, the harder the grade, the higher
the wear resistance of the cutting edge and longer the tool life.For
cemented carbides, the hardness will increase as the cobalt content
is decreased and also as the particle size of the tungsten carbide
is decreased.
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| Toughness |
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A method commonly used for determining the toughness
of cemented carbides is the indentation method. Here the fracture toughness
of the material is represented by its critical stress intensity factor
K1C. The results of toughness tests show that this property
increases with an increase in the cobalt content, and with increased
WC grain size |
| Density |
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Impermeable sintered metal materials and hardmetals — Determination
of density: ISO 3369
The density , usually expressed as grams per cubic centimeter, is checked
on each batch to ensure that the correct amount of cobalt was added.
The density of cemented carbide will increase as the amount of binder
is decreased. |
| Porosity Rating |
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Hardmetals — Metallographical determination of
porosity and uncombined carbon: ISO4505
This test involves a visual examination of a polished surface.
It is stated as "A" microporosity, "B" macroporosity,
or "C" as free carbon in the microstructure. |
| Microstructure uniformity |
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The uniform WC grain size distribution throughout the
microstructure is the preferred condition. The presence of individual
coarse WC grains in the microstructure can contribute to reduced tool
life. |
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