Hardness Testing 221

brale

A conical diamond indenter used in hardness tests. Brale indenters are used in Rockwell hardness tests.

Brinell hardness test

A hardness test that measures the diameter of a circle formed by the penetration of a 10 millimeter steel ball under a fixed load pressure. Brinell hardness values are abbreviated as "HB."

calibrated

Adjusting a measuring instrument against a standard to ensure its accuracy. Hardness testers must be calibrated using a calibration block with a known value.

case hardened

Heated within a carbon-rich environment to increase carbon levels on the metal surface. Case hardening creates a hardened exterior shell.

castings

A part formed by pouring or injecting heated material into a mold. Castings take shape as the material cools and solidifies.

cemented carbide

A compound developed by the combination of carbon with tungsten, titanium, tantalum, or other materials. Cemented carbide is used in hardness testing indenters and metal cutting tools due to its hardness and wear resistance.

dial indicator

A measuring instrument with a contact point, which is attached to a spindle, and gears that move a pointer on the dial. Dial indicators have graduations that are available for reading different measurement values.

diamond

A naturally occuring or manufactured stone made of crystalline carbon. Diamonds are often used in hardness testing indenters because they are the hardest known substance.

diamond pyramid hardness test

A hardness test that forces a pyramid-shaped diamond against a material for a standard dwell time to create an indentation. The diamond pyramid hardness test is also known as the Vickers hardness test.

durometer

A testing instrument with an indenter, calibrated spring, and dial indicator. Durometers are used in the Shore hardness test.

dwell time

An intentional time delay during a hardness test in which an indenter is held against a material under load. Dwell time is used to ensure accurate hardness ratings.

elastic

A material that has the ability to return to its original shape once it has been stretched or deformed. The hardness of elastic materials is often determined by Shore hardness testing.

elastic penetration

A temporary penetration of a material. When a material experiences elastic penetration, it will eventually return to its original shape.

elastic recovery

A period of slight rebound in a material after a load has been removed. During a hardness test, some materials experience elastic recovery and begin to return to their original shape after the major load is released.

feeds

The rate that the cutting tool travels along the surface of the workpiece. Feeds often involve linear movement from one point to another.

forgings

A metal part that is formed by compressing the metal at elevated temperatures. Forgings have aligned grains.

grinding

Using an abrasive to remove material from the surface of a part. Grinding is usually performed using abrasive wheels.

hammer

A small metal or diamond-tipped component used in rebound hardness testers. Hammers are found in scleroscope and Leeb equipment.

hardness

A material's ability to resist penetration. Hardness is usually measured by indention or vibration tests.

hardness value

A number from a hardness testing scale that indicates the ability of a material to resist scratching and penetration. Hardness tests use different scales that yield different hardness values.

heat treatment

Controlled heating and cooling processes used to change the structure of a material and alter its physical and mechanical properties. Annealing, quenching, and tempering are heat treatments.

indention hardness testing

A type of hardness test in which a hardened indenter is forced against a material under a fixed load. In indention hardness testing, the size of the indentation indicates the hardness of the material.

indicator

A device that displays a measurement. An indicator may be a dial with a needle or a digital readout.

inspection

The examination of a part to determine if it conforms to specifications. Inspection traditionally follows the completion of a part or the components that compose a part.

Knoop hardness test

A microhardness test that uses a small pyramid-shaped diamond indenter and relatively light loads between 10 grams and 1 kilogram. The Knoop indenter has a long diagonal that is perpendicular to and 7 times the length of the short diagonal.

Leeb hardness test

A portable hardness test that measures the rebound of a hammer mechanism. The Leeb hardness test can be administered from any angle regardless of gravity.

load

The force applied to an object by another object. Loads can cause materials to deform.

macrohardness tests

Hardness testing of normal-sized materials with standard loads, indenters, and dwell times. Macrohardness tests usually involve loads greater than 1 kilogram.

major load

The second and heaviest static load applied during a hardness test. The force of the major load varies, depending on the hardness test.

microhardness testing

Hardness testing that is designed to test thin or brittle test materials. Microhardness tests, or microindentation tests, usually involve loads less than 1 kilogram.

microhardness tests

Hardness tests that are designed to test thin or brittle test materials. Microhardness tests, also known as microindentation testing, usually involve loads less than 1 kilogram (kg).

microindentation testing

Hardness testing designed to test thin or brittle test materials. Microindentation tests, or microhardness tests, usually involve loads less than 1 kilogram.

microstructures

The shape and alignment of the microscopic components of a material. Microstructure is key in determining hardness, toughness, and other properties.

minor load

The first and lightest load applied to a material during a hardness test. The force of the minor load varies, depending on the hardness test.

ocular scale

A scale built into a microscope that makes it possible to view magnified images and measure very small features. Brinell hardness testing indentations can be measured using an ocular scale.

plastic penetration

A permanent penetration of a material. If a material is penetrated beyond its elasticity, the material experiences plastic penetration.

polishing

An abrasive finishing process used to improve the surface of a part. Polishing results in a smooth, shiny surface.

presser foot

The component on the bottom of a Shore hardness tester. The indenter is located in the middle of the presser foot.

rebound hardness testing

A type of hardness test that measures rebound of a mechanism dropped onto a test material. Leeb and scleroscope tests are examples of rebound hardness tests.

rhombus

A four-sided shape with opposite equal sides. A rhombus often resembles a diamond.

Rockwell hardness test

A hardness test that measures the degree of penetration into a material caused by a brale or ball indenter that is applied under a fixed load. Rockwell hardness testing applies two static loads to the material.

scleroscope test

A portable hardness test that measures the rebound of a hammer dropped from a fixed height. In scleroscope tests, higher rebounds equal higher hardness values.

Shore hardness test

A hardness test designed for elastic materials. The Shore tester is called a durometer.

speeds

The rate at which a cutting edge of the tool moves past the workpiece surface at the point of contact. Speed measures the rate of a rotational movement.

static loads

An external force that is applied and held in a fixed position for a specific amount of time. Static loads are an important component of standardized hardness tests.

Superficial Rockwell hardness test

A Rockwell test designed for thin test materials. The Superficial Rockwell test is identical to the Rockwell test, except that minor load is 3 kilograms and the major load is either 15, 30, or 45 kilograms.

tungsten carbide

A compound of tungsten and carbon that appears as very hard particles bonded together with a cobalt binder. Tungsten carbide is used to make Brinell hardness testing indenters, which are indicated by a "W" in Brinell notation.

ultrasonic microhardness test

A microhardness test that vibrates a Vickers diamond against a workpiece under a specific load. In ultrasonic microhardness testing, the change in frequency determines the material's hardness value.

ultrasonic microhardness test

A microhardness test that vibrates a Vickers diamond against a workpiece under a specific load. In ultrasonic microhardness tests, the change in frequency determines the material's hardness value.

Vickers hardness test

A hardness test that forces a pyramid-shaped diamond against a material for a standard dwell time to create an indentation. The Vickers hardness test is also known as the diamond pyramid hardness test.

Vickers microhardness test

A Vickers hardness test used to test small or thin materials. The Vickers microhardness test uses light loads between 1 gram and 2 kilograms.