Resumen:
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Consulta en la Biblioteca ETSI Industriales (7816)
[EN] This work is about analysis of structural, mechanical and technological properties of
aluminium assigned to bulk forming processes.
Almost in all metal forming processes the tools are operating with pressure on ...[+]
[EN] This work is about analysis of structural, mechanical and technological properties of
aluminium assigned to bulk forming processes.
Almost in all metal forming processes the tools are operating with pressure on deformed
material surface. This results in arising friction forces on tool ¿ material contact
surface and it is the reason of inhomogeneity of stress and strain on the inside of deformed
material. As a result of external friction forces, non-uniform distribution of unit
pressure and its essential growth over yield stress occurs on contact surfaces, too.
Tensile test is commonly used to determine mechanical properties of materials.
Such properties as yield point, tensile ultimate strength, unit elongation, reduction of
specimen area, obtained in tensile test are very important in strength of materials. These
parameters are often used in metal forming to estimate the usability of a material, but
they are not technological parameters.
The opposite of tensile test, with respect to the direction of loading, is compression
test. In compression test the specimen is squeezed and friction forces, which arise on
thrust surface, are diminished (for instance by lubricants). Compression test results in
mechanical properties that include the compressive yield stress, compressive ultimate
stress, compressive modulus of elasticity and others. These strength values are calculated
using the original cross sectional area of specimen and are named nominal or engineering
values, what is likewise in tensile test.
Upsetting test is like a compression test realized between flat dies and it is close to
technological conditions of metal forming. During the test, on the die-specimen contact
surface friction forces arise and the barrelling of specimen side surface occur. The barrelling
is the result of non-homogeneous stress and strain in the process. When press load
and ram displacement are recorded, unit pressure - strain curves can be determined up to
very high strains, considerably greater than in tensile test. The upsetting force and strain
are not only material dependent but also the test conditions.
The hardness test is, together with the one of traction, one of the most used in the
selection and control of quality of metals. Intrinsically the hardness is a condition of the
surface of the material and it does not represent any fundamental property of the matter.
It is evaluated conventionally by two procedures. The hardness is a fundamental property
of the materials and this related to the mechanical resistance.
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