definitions Flashcards
Alloy
A metallic substance that is composed of two or more elements
Anisotropic
Exhibiting different values of a property in different crystallographic directions
Annealling
A generic term used to denote a heat treatment in which the microstructure and, consequently, the properties of a material are altered. Frequently refers to a heat treatment whereby a previously cold-worked metal is softened by allowing it to recrystallize.
Charpy Test
A test used to measure the impact energy or notch toughness of a standard notched specimen. An impact blow is imparted to the specimen by means of a weighted pendulum
Design Stress
Produce of the calculated stress level (on the basis of estimated load) and a design factor (which has a greater value than unity). Used to protect against unanticipated failure.
Drawing
A forming technique used to fabricate metal wire and tubing. Deformation is accomplished by pulling the material through a die by means of a tensile force applied on the exit side
Ductility
A measure of a material’s ability to undergo appreciable plastic deformation before fracture; it may be expressed as percentage elongation(%EL) or percentage reduction in area (%RA) from a tensile test.
Elastic deformation
Deformation that is non-permanent - that is, totally recovered upon release of a mechanical stress.
elastic recovery
Non-permanent deformation recovered or regained upon release of a mechanical stress.
Extrusion
A forming technique by which a material is forced, by compression, through a die orifice.
Fatigue
Failure, at relatively low stress levels, of structures that are subjected to fluctuating and cyclic stresses.
Forging
Mechanical forming of a metal by heating and hammering
Fracture toughness
The measure of a material’s resistance to fracture when a crack is present.
Hardness
The measure of a material’s resistance to deformation by surface indentation or by abrasion
Hot working
Any metal forming operation performed above a metal’s recrystallization temperature.
Impact energy
A measure of the energy absorbed during fracture of a specimen of standard dimensions and geometry when subjected to very rapid (impact) loading. Charpy impact testing is one test to measure this parameter. It is important in assessing the ductile-to-brittle transition behaviour of a material.
Modulus of elasticity
The ratio of stress to strain when deformation is totally elastic; also a measure of the stiffness of a material.
Plastic deformation
Deformation that is permanent or non-recoverable after release of the applied load. It is accompanied by permanent atomic displacements.
poissons ratio
For elastic deformation, the negative ratio of lateral and axial strains that result from an applied axial stress
Powder Metallurgy
The fabrication of metal pieces having intricate and precise shapes by the compaction of metal powders, followed by a densification heat treatment.
residual stress
A stress that persists in a material free of external forces or temperature gradients.
Rupture
Failure accompanied by significant plastic deformation; often associated with Creep failure.
Engineering strain
The change in gauge length of a specimen (in the direction of an applied stress) divided by its original gauge length.
True strain
he natural logarithm of the ratio of instantaneous gauge length to original gauge length of a specimen being deformed by a uniaxial force.
