Metals testing is very important to show the various properties of metals and the defects
which may found in it during production or during its service.
Classification of metals testing:
1- Destructive tests.
2- Non-destructive tests.
3- Technological tests.
4- Chemical tests.
5- Electrochemical test (Corrosion test).
6- Metallographic tests.
In the following the different classes of material tests will be discussed briefly.
1- Destructive tests.
Destructive material tests are the kind of tests where the test specimen destroys after
the test and could not be used. The test specimens for destructive tests can be a
sample taken out from
- a piece of a semi-product (sheet, rod, section).
- a sample of the final products (bolts, shafts), or any simple structure.
Destructive tests are:-
1. Tensile test
2. Compression test
3. Bending test
4. Impact test
5. Creep test, and stress relaxation test.
6. Fatigue test
2-Non-destructive materials test
They are tests that carry out on specimens of material products or on specimens of
machine parts or structure during the service without changing their functions to find out
their defects. The following tests are classified as non-destructive tests :-
1- Radio graphic test
2- Magnetic test
3- Electrical test
4- Ultra-sonic test
5- Some hardness test
3-The technological test
It is usually rapid methods, which give an idea whether metal is suitable for a special purpose or
not, e.g. testing a metal to know its liability to forging, rolling, bending or deep drawing.
Technological test such as:-
1- Spark test
Some metal can be estimated by spark test wherever some metal give spark (Fe) and
the other (Mo) not.
The spark density, color and it’s shape can also define the type of metal under the
testing.
2- Worm compression test
The shape and distribution of the cracks on carrying out a warm compression gives an
indication about the type and properties of the metal.
3- Bending test
Bending of sheets for several times, it gives an indication for the ability of deep
drawing of metal under testing.
5- Folding test
by folding the sheet to show its ability of forming.
6- Hammering test
from the sound of hammer or the deformation resulting from the
hammering, some indications could be obtained about the metal.
Technological tests do not give a quantitative result, but give an idea about the different
properties of the metals or its stability for the working purposes.
which may found in it during production or during its service.
Classification of metals testing:
1- Destructive tests.
2- Non-destructive tests.
3- Technological tests.
4- Chemical tests.
5- Electrochemical test (Corrosion test).
6- Metallographic tests.
In the following the different classes of material tests will be discussed briefly.
1- Destructive tests.
Destructive material tests are the kind of tests where the test specimen destroys after
the test and could not be used. The test specimens for destructive tests can be a
sample taken out from
- a piece of a semi-product (sheet, rod, section).
- a sample of the final products (bolts, shafts), or any simple structure.
Destructive tests are:-
1. Tensile test
2. Compression test
3. Bending test
4. Impact test
5. Creep test, and stress relaxation test.
6. Fatigue test
2-Non-destructive materials test
They are tests that carry out on specimens of material products or on specimens of
machine parts or structure during the service without changing their functions to find out
their defects. The following tests are classified as non-destructive tests :-
1- Radio graphic test
2- Magnetic test
3- Electrical test
4- Ultra-sonic test
5- Some hardness test
3-The technological test
It is usually rapid methods, which give an idea whether metal is suitable for a special purpose or
not, e.g. testing a metal to know its liability to forging, rolling, bending or deep drawing.
Technological test such as:-
1- Spark test
Some metal can be estimated by spark test wherever some metal give spark (Fe) and
the other (Mo) not.
The spark density, color and it’s shape can also define the type of metal under the
testing.
2- Worm compression test
The shape and distribution of the cracks on carrying out a warm compression gives an
indication about the type and properties of the metal.
3- Bending test
Bending of sheets for several times, it gives an indication for the ability of deep
drawing of metal under testing.
5- Folding test
by folding the sheet to show its ability of forming.
6- Hammering test
from the sound of hammer or the deformation resulting from the
hammering, some indications could be obtained about the metal.
Technological tests do not give a quantitative result, but give an idea about the different
properties of the metals or its stability for the working purposes.
4- Chemical tests
Chemical analysis is carried out on the metals and alloys for the following purposes:
- To identify the quantity and types of the inclusions (sulphides, oxides).
- To show the percentage of the alloying elements.
The well known electrochemical test is the corrosion test, to show the activity of the
metals and alloys in different environments; i.e. in different chemical medium and under
different current density. Other electrochemical experimental tests are the metal wining
test (such as copper refining) and metal plating.
It is the study of microstructure of the specimen on the prepared cross section under an
optical microscope (up to a magnification of 2000X) or studying the macrostructure
under low magnification stereomicroscope (up to 20X).
The purposes of metallographic are:-
1- Structure of phases; i.e. shape and distribution of graphite in grey cast iron,
cementite in white cast iron and distribution and area fraction of reinforcing
component in composite materials.
2- Density and length of micro-cracks.
3- Grain size of the micro- and macrostructure.
4- Type and morphology of the inclusions.
5- The form and distortion of the grain gives an indication about the type of deformation
(rolling, bending).
6- Identification of the type of stress leading to the failure of the damaged materials
(creep failure, fatigue, stress corrosion cracking, …).
Chemical analysis is carried out on the metals and alloys for the following purposes:
- To identify the quantity and types of the inclusions (sulphides, oxides).
- To show the percentage of the alloying elements.
5- Electrochemical test
The well known electrochemical test is the corrosion test, to show the activity of the
metals and alloys in different environments; i.e. in different chemical medium and under
different current density. Other electrochemical experimental tests are the metal wining
test (such as copper refining) and metal plating.
6- Metallographic test
It is the study of microstructure of the specimen on the prepared cross section under an
optical microscope (up to a magnification of 2000X) or studying the macrostructure
under low magnification stereomicroscope (up to 20X).
The purposes of metallographic are:-
1- Structure of phases; i.e. shape and distribution of graphite in grey cast iron,
cementite in white cast iron and distribution and area fraction of reinforcing
component in composite materials.
2- Density and length of micro-cracks.
3- Grain size of the micro- and macrostructure.
4- Type and morphology of the inclusions.
5- The form and distortion of the grain gives an indication about the type of deformation
(rolling, bending).
6- Identification of the type of stress leading to the failure of the damaged materials
(creep failure, fatigue, stress corrosion cracking, …).
Classification of materials testing depending on the rate of loading:
Metals testing are carried out under a very wide range of strain rates ε/dt) ranging between
between 10 sec .
Static and very slow rate tests:-
Such as creep tests which prolonged over a very long time (up to 10 years)
Quasi-static tests:-
It is the region of loading range where most traditional tests such as tensile test,
compression test and bending test are carried out. This range lying around a strain rate
range of 0.001 sec ¯¹.
Higher strain rate deformation:-
It is the range of testing that occurs at the strain rate range between 0.1 and 100 sec¯¹ .
This strain rate range covers the usual rolling forging and drawing processes.
High strain rate and crash tests:-
It is the range of testing simulating the high strain rate deformation and the deformation
occurring at the crash conditions. At these conditions impact test and crash test are
usually carried out where the strain rate is more than 100 sec¯¹ .
Metals testing are carried out under a very wide range of strain rates ε/dt) ranging between
between 10 sec .
Static and very slow rate tests:-
Such as creep tests which prolonged over a very long time (up to 10 years)
Quasi-static tests:-
It is the region of loading range where most traditional tests such as tensile test,
compression test and bending test are carried out. This range lying around a strain rate
range of 0.001 sec ¯¹.
Higher strain rate deformation:-
It is the range of testing that occurs at the strain rate range between 0.1 and 100 sec¯¹ .
This strain rate range covers the usual rolling forging and drawing processes.
High strain rate and crash tests:-
It is the range of testing simulating the high strain rate deformation and the deformation
occurring at the crash conditions. At these conditions impact test and crash test are
usually carried out where the strain rate is more than 100 sec¯¹ .
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