Properties for Fasteners 200

alloy-steel

A type of steel that contains additional elements to improve the properties of a fastener.

aluminum

A silvery, white metal that is soft, light, and is electrically and thermally conductive.

bending load

A force that is applied in the middle or on the end of an object causing the object to bend in a curve.

bolt fracture

A type of fastener failure that occurs when a fastener is over-tightened and causes the bolt to break.

Brinell scale

A method for testing a material's hardness that forces a hard steel sphere under a specified load into the surface of a material and measuring the diameter of the indentation left after the test.

bronze

An alloy of copper and tin. Bronze is highly corrosion resistant.

carbon steel

A type of steel made up of iron and carbon and no other material. Most fasteners are made from carbon steel.

clamping force

The compressive force that a fastener exerts on a joint.

cold working

The shaping of metal at temperatures much lower than the metal's molten state. Cold working increases the strength in certain steels.

compression load

A pushing or pressing force that is directed toward the center of an object.

copper

A reddish-brown metal that is very ductile, thermally and electrically conductive, and corrosion resistant. Copper fasteners are often used for electrical components.

corrosion

The gradual chemical attack on a metal by atmosphere, moisture, or other agents.

corrosion resistance

The ability of a material to resist chemical destruction from an environment. Corrosion resistance is the most important physical property for fasteners.

density

The relative compactness of a material. Density is the mass of a material per unit volume.

ductility

The ability of a fastener material to deform before it fractures.

elastic limit

The maximum stress a material can support before it deforms. Elastic limit is also known as yield strength.

electrical conductivity

The ability of a material to conduct an electrical current.

elongate

To extend the length of an object.

fatigue

A type of fastener failure that occurs when a fastener is subjected to repetitive loading or stressing. Fatigue can cause catastrophic failure.

fatigue strength

The maximum stress a fastener can withstand for a specific number of repeated applications prior to its failure.

ferrous

A metal that contains iron. Carbon steels are common ferrous metals.

grade

A category that fasteners are grouped in according to their strength.

grade identification

The marking on the head of a bolt that indicates tensile strength.

hardness

The measure of a fastener's ability to resist penetration, indentation, and scratching

heat treatment

The heating and cooling processes used to change the structure of a material and alter its mechanical properties.

hex-head bolt

A type of bolt that has a head with six sides.

indenter

A device used in a hardness test that is pressed into the test material.

load

The overall force that is applied to a material or structure. A fastener that supports the weight of an object is withstanding a load.

low-carbon steel

A type of carbon steel that contains less than 0.3% carbon. Grade 2 fasteners are common low-carbon steel fasteners.

mechanical properties

The properties that describe the way a material responds to forces that attempt to bend, break, twist, dent, or scratch it. Mechanical properties are the most important properties for fasteners.

medium-carbon steel

A type of carbon steel that contains between 0.3% and 0.5% carbon. Grade 5 fasteners are common medium-carbon steel fasteners.

megapascal

The metric unit of pressure. Megapascal is abbreviated Mpa.

nonferrous

A metal that does not contain iron. Aluminum, copper, and zinc are nonferrous metals.

non-threaded fastener

A type of fastener that does not contain threads. Pins, retaining rings, and rivets are examples of non-threaded fasteners.

off-torque

The force that is proportional to torque in the opposite manner. An off-torque condition causes the fastener to rotate loose.

overloading

A type of fastener failure that occurs when an excessive load is applied to a bolt, which causes the bolt to yield or fracture.

permanent deformation

The stress that causes a fastener to lose its original shape and appearance.

physical properties

The properties that describe the way a material responds to external environment conditions, such as temperature, chemical exposure, and electricity. Corrosion resistance is the most important physical property for fasteners.

pounds per square inch

A unit of pressure that measures the amount of load pressure per inch. Pounds per inch is abbreviated psi, or pounds per square inch.

preload

The tension created in a fastener when it is first tightened. Preload must be greater than the external forces applied to the assembly to prevent joint failure.

proof load

The amount of stress that the fastener can withstand without experiencing deformation. Proof load is often used interchangeably with yield strength.

properties

The characteristics of a material that distinguish it from other materials.

protective coating

A layer applied over metal that contains elements, which prevent the metal from damage.

Rockwell scale

A method for testing a material's hardness that uses an indenter to test the material's resistance to deformation as a load is applied.

shear strength

The ability of a fastener material to resist internal sliding.

shearing

The cutting and separating of material through its cross section.

socket screw

A type of capscrew with a round head and a hexagonal indentation for tightening purposes.

strength

The ability of a material to resist stress caused by forces attempting to break or deform the material.

stress

The applied force over a certain area that tends to deform an object or structure.

stud

An externally threaded fastener that is often threaded at both ends and can be used with a nut. Unlike bolts, studs do not have a head.

synthetic

Something that is produced artificially. Synthetic materials include plastic and nylon.

tensile strength

The maximum stress a fastener can endure before it breaks. Tensile strength is the most important property associated with threaded fasteners.

tension load

A pulling force that is directed away from the object and attempts to stretch or elongate the object.

thermal conductivity

The ability of a material to conduct heat.

thermal expansion

The tendency of a material to increase in size as it increases in temperature.

thread stripping

A type of fastener failure that occurs when a fastener is over-tightened. Thread stripping causes the fastener threads to appear deformed.

threaded fastener

A type of fastener that contains threads. Bolts, screws, and nuts are examples of threaded fasteners.

tolerance

The unwanted but acceptable deviation from a specified dimension.

torque

The amount of force applied to tighten a bolt, screw, or nut.

torsion test

A test that involves twisting an object to test a material's shear strength.

torsional load

A force that is applied by clamping one end of an object and twisting the other.

torsional strength

The ability of the fastener to resist a torque that attempts to twist a fastener off its axis.

traceability

The ability to trace the history, application, or location of an item using documentation.

ultimate tensile strength

The final amount of stress sustained in a tensile test at the exact moment the object ruptures.

vibration loosening

A type of fastener failure that occurs in a bolted joint due to excessive motion, which causes the bolt to rotate loose.

Vickers scale

A method for testing a material's hardness that uses a pyramid-shaped diamond to exert pressure on the surface of a material for a standard length of time. The diagonal of the indentation is measured under a microscope to determine the hardness value.

washer

A flat disc with a hole through the center that is often used with threaded fasteners to ensure tightness of the joint.

wedge tensile test

A procedure used to test tensile strength in which a washer with a beveled surface is placed under the head of a fastener causing a bending stress.

yield strength

The maximum force that a fastener can withstand before it experiences permanent deformation.