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| a diamond-tipped 120° cone used in a Rockwell hardness test. |
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| The stress at which fracture occurs. |
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| Used in a Brinell Hardness Test, it is equal to the load divided by the surface are of the spherical indentation which the units are expressed as kilograms per square millimeter. It is found from a table that correlates the Brinell number with the diameter of the indentation preduced under various loads. |
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| A hardness test in which a ball is pushed into the flat surface of a material and left for 10-15 seconds before the mark is measured to see how big of a diameter was left. |
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| The lack of significant ductility. |
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| A bending impact test in which the standard specimen contains a V, keyhole, or U-shaped notch. The specimen is supported on both ends and and impact is applied to the center, behind the notch, to complete a three-point bending. The bending impact is measured by measuring the angle of the rebound of the hammer that caused the impact. |
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| Long-term exposure to elevated temperatures can lead to creep. The materials elongates continuously until rupture occurs. |
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| Rate of elongation during creep |
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| A defect whose size remains unchanged theourh the lifetime of the part. |
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| Ductile-to-brittle transition temperature |
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| The temperature at which the response goes from high energy absorption to low energy absorption |
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| The amount of plasticity that precedes fracture. For metal deformation processes, the greater the ductility, the more a material can be deformed without failure. |
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| An instrument that measures the resistance of a material to elastic penetration by a spring-loaded conical steel indenter. No permanent deformation occurs |
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| A defect whose size changes throughout the lifetime of the part. |
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| The uppermost stress for which the response of the stress is elastic. It is always slightly higher than the proportional limit. |
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| How much a material conducts electricity. |
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| How much a material resists electricity. |
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| Stretch over a specified length. |
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| The value of the stress below which the material will not fail regardless of the number of load cyclyes. |
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| e, The elongation (ΔL) divided by the original gage length Lo. |
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| S, The applied load (W) divided by the original cross-sectional area (Ao). |
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| When a material fails by fracture when it is subjected to repeated applications of stress, even though the peak stresses have magnitudes less than the ultimate tensile strength and usually less than the yield strength. |
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| The maximim stress that can be sustained for a specific number of loading cycles. |
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| Ridges formed around a fracture in the smooth areas of the fracture. The ridges radiate away from the fracture. |
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| How a material reacts to being formed. |
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| The materials portion of fracture mechanincs. |
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| The specified length used in determining elongation |
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| A very important but hard-to-define property of engineering materials. There are several tests to test the hardness of a material. |
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| The amount of energy that must be added or removed from a given mass of material to produce a 1° change in temperature. |
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| A bending impact test in which the standard specimen is supported like a cantilever beam and is impacted on the end. The bending impact is measured by measuring the angle of the hammer that hits it. |
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| Tests that evaluate the fracture resistance of a material when it is subjected to a rapidly applied dynamic load, or impact. |
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| A microhardness test in which an elongated diamond is pressed against a material and a microscope is used to measure the length of the diamond. |
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| Can mean many things but mostly, how a material reacts to being worked with by a machine |
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| Properties that describe how a material responds to applied loads (or forces). |
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| Have luster, high thermal conductivity, high electrical conductivity, are relatively ductile, and some have magnetic properties. Examples: iron, copper, aluminum, magnesium, nickel, titanium, lead, tin, and zinc. Alloys: steel, brass, bronze |
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| A very exact type of hardness test in which a microscope is used to examine a small indentation. |
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| Same as Young's Modulus. The proportionality constant or ratio of stress to strain in a particular region. Shown on Engineering stress-strain diagram as graph below the proportional limit. It is an inherent property of a given material and is of considerable engineering importance. |
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| The weakest location in the test specimen at that time continues to be the weakest location by virtue of the decrease in area, and further deformation becomes localized. This localized region in cross-sectional area is known as necking. |
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| Less ductile, weaker and less dense than metals, poor electrical and thermal conductiveness. Examples: wood, brick, concrete, glass, rubber, and plastics. |
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| The value of the stress that will produce a given, but tolerable, amount of permanent strain. For most components, the amount of offset strain is set at 0.2%. It is determined by drawing a line parallel to the elastic line, but displaced by the offset strain. |
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| Percent reduction in area |
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Definition
| Original cross-sectional area - Smallest area in the necked region / Original cross-sectional area * 100% |
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| Characteristics such as density (weight), melting point, optical properties (transparency, opaqueness, or color), thermal properties of specific heat, coefficient of thermal expansion, thermal conductivity, electrical conductivity, magnetic properties. |
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| Elongation past the elastic limit becomes unrecovable and becomes plastic deformation. |
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| The stress at which the strain and stress are directly proportional to in a engineering stress-engineering strain curve. It is always slightly lower than the elastic limit. |
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Definition
| The amount of energy that a material can absorb while in the elastic range. |
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| A hardness test similair to the Brinell hardness test in which a minor load and then a major load are applied to the surface of a material and the depth of the permanent indentation is meaured. |
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| A curve that summarizes the results of multiple fatigue tests. |
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| Measures the resilience of a material by checking the rebound of a small diamond tipped hammer that is dropped from a fixed height onto a material. |
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Definition
| A measurable physical quantity which characterizes the amount of heat required to change a body's temperature by a given amount. |
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Definition
| Properties of a material when the material is in a static state, meaning that all forces applied to the material are constant or nearly so. |
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| When a force or load is applied to a component, the material is deformed or distorted (Strained) |
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Definition
| Plastically deforming to make a metal stronger and/or harder |
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| Strain-hardening coefficient |
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Definition
| n in the equation σ=Kε^n. A meaterial with a high strain-hardening coefficient will have a significant increase in material strength with a small amount of deformation. A material with a small strain-hardening coefficient will show little change in strength with plastic deformation. |
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Definition
| The force or load being transmitted divided by the cross-sectional area transmitting the load. S=W/A. Measured in megapascals or pounds per square inch. |
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Definition
| A diagram that shows the rupture time data that is collected through various tests. |
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| An impact test in which the specimen is subjected to a uniaxial impact loadings applied through drop weights, modified pendulums, or variable-speed flywheels. |
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Definition
| Measures the rate at which heat can be transported through a material. |
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Definition
| The amount expansion or contraction a material undergoes while being heated or cooled. |
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| Time to rupture (rupture time) |
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Definition
| Total elapsed time before the rupture during creep. |
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Definition
| The work per unit colume required to fracture a material. |
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Definition
| The temperature at which a material changes from one crystal state to another. There are seven crystal systems and every material exists in one of them. |
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Definition
| ε, The summation of the incremental strains that occur throughout the test. ε= ln(L/Lo) |
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Definition
| σ, The applied load (W) / Actual area |
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| Ultimate tensile strength |
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Definition
| The stress at which the load-bearing ability peaks. |
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Definition
| A standard specimen is loaded in tension in a testing machine. The standard specimens ensure meaningful and reproducible results, and are designed to produce uniform uniaxial tension in the central portion of the specimen while ensuring reduced stresses in the sections that are gripped. |
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Definition
| A hardness test similair to the Brinell hardness test in which a 136° square-based diamond pyramid is used to make an indentation in the material that is then measured to determine the hardness of the material. This test is beneficial because the square-shaped indentation is easier to measure than the circle of the Brinell Hardness Test. Also, the diamond point allows the test to be used on any material. |
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Definition
| How easily a material can be welded. |
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Definition
| A sress value present in some materials that may be reached where additional strain occurs without any stres increase. |
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Term
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Definition
| Same as Modulus of Elasticity. The proportionality constant or ratio of stress to strain in a particular region. Shown on Engineering stress-strain diagram as graph below the proportional limit. It is an inherent property of a given material and is of considerable engineering importance. |
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