Properties of Engineering Materials

Vocabulary-based flashcards defining engineering materials, their various chemical, physical, and mechanical properties, and standard methods for measuring and testing material behavior.

METALS

Combinations of metallic elements that have large numbers of localized electrons not bound to particular atoms; they are strong yet deformable.

CERAMICS

Compounds between metallic and non-metallic elements such as oxides, nitrides, and carbides; they are typically insulative to electricity and heat.

POLYMERS

Plastic and rubber materials consisting of organic compounds chemically based on carbon, hydrogen, and other non-metallic elements with large molecular structures.

COMPOSITES

Materials consisting of more than one material type designed to display a combination of the best characteristics of each component.

SEMICONDUCTORS

Materials with electrical properties intermediate between electrical conductors and insulators.

BIOMATERIALS

Materials employed in components implanted into the human body for replacement of diseased or damaged body parts.

METALLIC materials

Materials that exhibit electrical and thermal conductivity and luster.

FERROUS

Iron-based materials including steel, cast iron, wrought iron, and malleable cat iron.

NON-FERROUS

Metallic materials such as copper, tin, zinc, aluminum, magnesium, and titanium.

NON-METALLIC materials

Materials that have poor electrical and thermal conductivities, are less ductile, weaker, and less dense than metals.

CHEMICAL PROPERTIES

Characteristics relating to behavior in chemical reactions, particularly corrosion, alloying, and compound formation.

PHYSICAL PROPERTIES

Distinguishing qualities used to describe a substance in the absence of external forces, such as specific heat, density, and color.

MECHANICAL PROPERTIES

Properties describing the behavior of material under force, including strength, hardness, machinability, ductility, elasticity, and plasticity.

ELECTRICAL PROPERTIES

Properties where the stimulus is an electric field, represented by electrical conductivity and dielectric constant.

THERMAL PROPERTIES

The behavior of solids represented in terms of heat capacity and thermal conductivity.

MAGNETIC PROPERTIES

The response of a material to the application of a magnetic field.

OPTICAL PROPERTIES

Properties where the stimulus is electromagnetic or light radiation, such as index of refraction and reflectivity.

DETERIORATE PROPERTIES

Characteristics indicating the chemical reactivity of materials.

ELASTICITY

The property of regaining the original shape upon the removal of the external load.

PLASTICITY

The property of a material by virtue of which permanent deformation can occur.

RESILIENCE

The capacity of a material to absorb energy within the elastic range.

DUCTILITY

A quality of material indicating it may be plastically elongated or stretched easily without cracking or breaking.

MALLEABILITY

A quality of material in which it may be plastically compressed or hammered into thin sheets without fracture.

TOUGHNESS

The total energy-absorbing capacity of the material, including elastic and plastic deformation, and resistance to shock.

HARDNESS

Resistance to scratching, penetration, denting, or wear.

STRAIN

Deformation caused by the application of an external force.

STRESS

Internal forces established which tend to restore atoms to their original position.

HOOKE’S LAW

The relationship showing that strain and stress are directly proportional.

MODULUS OF ELASTICITY

The defined limits where deformation is directly proportional to the applied force.

MODULUS OF RUPTURE

Computed strength which does not bear a specific relationship to the maximum stress the material will sustain before fracture.

TENSION TEST

A test used to determine how a material will behave under the application of tensile forces.

EXTONSOMETER

A delicate instrument used to measure the extension of a test specimen.

PROPORTIONAL LIMIT

The maximum stress to which a material can be subjected without deviation from the proportionality of stress and strain.

ELASTIC LIMIT

The maximum stress to which a material may be subjected without any permanent strain remaining upon complete release.

YIELD POINT

A stress reached where the material continues to elongate for a time without an increase of load once increased beyond the elastic limit.

YIELD STRENGTH

A stress at which the material exhibits a specified limiting permanent set.

ULTIMATE STRENGTH

The maximum stress to which a material may be subjected before failure occurs.

BRINELL TEST

Hardness test using a $10\,mm$ hardened steel ball pressed with either $3000\,kg$ (hard) or $500\,kg$ (soft) force for $30\,sec$.

DIAMOND PYRAMIC HARDNESS (DPH)

Test using a diamond pyramid penetrator with an angle of $136^\circ$ between opposite faces.

ROCKWELL TEST

Test using a diamond cone (hard) or $1/16\,in.$ steel ball (soft) with a minor load of $10\,kg$ and major load of $150\,kg$ or $100\,kg$.

SCLEROSCOPE TEST

Measures the height of rebound of a diamond-tipped hammer to determine resilience rather than resistance to penetration.

MICROHARDNESS TEST

Determination of hardness for relatively thin sheets of metal using small penetration forces.

ROCKWELL SUPERFICIAL HARDNESS TESTER

Tester that uses loads as low as $15\,kg$ applied to the penetrator.

TUKON HARDNESS TESTER

Tester using either a $136^\circ$ diamond pyramid or a knoop indentor.

MONOTRON TEST

Test using a $0.75\,mm$ hemispherical diamond indentor or a $1/16\,in.$ ($2.5\,mm$) tungsten carbide indentor.

DYNAMIC LOADING

Load application which leads to rapidly changing stresses.

IMPACT LOADING

A type of dynamic loading where stress is applied instantaneously.

RAPID LOADING

A type of dynamic loading where the load is applied more gradually or suddenly.

WORKING STRESS

The actual stress which the material is expected to operate.

ALLOWABLE STRESS

The stress below which it is known that failure will not take place; equals the elastic limit under static conditions.

FACTOR OF SAFETY

The ratio of allowable stress to working stress defined by the formula $\text{Factor of Safety} = \frac{\text{Allowable Stress}}{\text{Working Stress}}$.