Exam 1 3400

The stress values in engineering stress-strain curves are calculated using the which area of the specimen.

Initial cross-sectional area

An _________ is an atom that has lost or gained an electron Neutron Proton Ion Micron

Ion

_________ is a physical blend of two or more substances.

MIXTURE

Which one is a SI unit for strength?

MPa

________ properties are characteristics of a substance related to its durability and ability to withstand applied forces. Mathematical Chemical Mechanical Biological Physical

Mechanical

Which of the following is NOT a mechanical property? Fatigue Strength Toughness Hardness Tensile Strength Melting Point

Melting Point

SI units of Stress is

N/m 2

What makes elements different from each other? Number of elements Number of protons Electron spins Number of atoms

Number of protons

________ properties are attributes of a substance that can be measured without altering or destroying it. Mechanical Chemical Physical Biological Mathematical

Physical

___________ is the most industrially important strengthening mechanism in metals. Metal forging Quench hardening Plumbing Welding

Quench Hardening

What is an atom? The smallest part of a substance An element Neutrons A form of energy

The smallest part of a substance

Which one is a physical property? Corrosion Friction All of them Hardness Toughness Thermal Expansion Strength Composition

Thermal Expansion

Aluminum expands twice as much as steel, this is called ____________. Thermal conductivity Thermal expansion Use Temperature Thermal heat

Thermal expansion

Which one is NOT one of the basic type of stresses? Tensile stress Toughness stress Shear stress Compressive stress Torsional stress Bending stress

Toughness stress

What is Poisson's ratio ?

Transverse strain (diameter direction) / longitudinal strain (length direction)

An atom is the smallest part of a substance that retains the properties of that substance. True False

True

Before the ultimate tensile stress is reached, the rate of work hardening in the material increases faster than the reduction in cross-sectional area.

True

Bending stress deflects a member.

True

Both ionic and covalent bonds involve strong bonds between neighboring atoms. True False

True

Ceramics are electric insulators

True

Corrosion is the degradation of a material by reaction with its environment.

True

Creep is used to rate the resistance of a material to plastic deformation under sustained load.

True

Crystalline ceramics with strong bonds tend to be brittle.

True

Dislocations can be caused by the atomic mismatch effects of adding alloy elements.

True

Dislocations can be produced by crystal mismatch in solidification.

True

Ductility is also reported as percent elongation or percent reduction in area

True

General shape of the curve is the area under the curve provides a relative indication of material toughness.

True

If the atoms of the alloying element are significantly larger than the atoms of the host metal, these large atoms can impede the motion of dislocations and thus strengthen the metal. True False

True

In a stress strain curve, the midpoint of the curve is called yield strength.

True

In the tensile test, the sample can continue to elongate until the permanent plastic deformation occurs.

True

Inert gases can be used for providing protective atmospheres

True

Iron, nickel, cobalt have ferromagnetism.

True

Many metals can tolerate plastic deformation before failing.

True

Metal usually can be deformed plastically.

True

Metal usually can be strengthened. True False

True

Modulus of elasticity E= stress/strain = σ/ε.

True

Modulus of elasticity is used to measure the stiffness of materials

True

Most engineering literature uses the engineering stress- strain technique.

True

Protons, neutrons, and electrons have mass.

True

Shear stresses are proportionally related to the shear strains through an elastic constant called the shear modulus.

True

Strength is a materials ability to accommodate stress

True

The fatigue strength or endurance limit of a material is obtained by repeatedly loading a specimen at given stress levels until it fails.

True

The outer electron shell of atoms will be complete when it contains eight electrons.

True

The point at which the deformation of the material transitions from elastic deformation to plastic deformation is referred to as Yield point.

True

Thermal Expansion becomes important when dissimilar materials will be fastened and heated

True

True stress-strain curves are more difficult to measure and calculate because of the changing of the cross-sectional area.

True

When a bar is pulled axially in the elastic regions, the ratio of the two strains, lateral : axial, is called Poisson's Ratio.

True

When a material is plastically deformed, the material becomes stronger and harder.

True

When metals are deformed by dislocation motion, the more barriers the dislocations meet, the stronger the metal. True or False

True

Wood is a composite of cellulose fibers held together with a glue.

True

_________ is more difficult to measure and calculate because the cross-sectional area of the specimen must be accounted for as it necks down.

True stress-strain curve

At what point, the rate of cross-sectional area reduction occurs faster than the work hardening rate. Ultimate tensile stress Break Yield stress Creep Pulling stress

Ultimate tensile stress

In a stress-strain curve, the end point of Elastic region is called

Yield Strength

What property describes the weight or mass of materials

gravimeter

Which material below is the best for electric insulators? saline water alloys polymers metals

polymers

Which one is a mechanical property of gold? Its unique color Does not corrode in water or air Soft and malleable Does not tarnish (oxidize)

soft and malleable

In true stress-strain testing, an equation may be used to approximate the shape of the plastic region of the stress-strain curve What does the " n" represent?

strain hardening exponent

Modulus of elasticity = ------ /------

stress/strain

Which of the following is not a chemical property Solubility Composition Corrosive nature Specific gravity

Specific Gravity

__________ is the amount of heat energy required to raise one unit mass of material with one degree. Thermal conductivity Use temperature Thermal expansion Specific heat

Specific heat

Which one is a mechanical property? Composition All of them Specific Heat Strength Density Color Atomic Structure

Strength

In true stress-strain testing, an equation may be used to approximate the shape of the plastic region of the stress-strain curve What does the " K" represent?

Strength coefficient

Metals are inorganic materials. True False

TRUE

Resilience is a prosperity defines a material's ability to absorb elastic energy.

TRUE

The formula for calculating the Percent of Elongation is (Final length - initial length) / Final length (Initial length - final length) / Initial length (Final length - initial length) / Initial length (Initial length - final length) / Final length

(Final length - initial length) / Initial length

What poission's ratio does most of engineering materials have? 7 14 0.01 0.3

.3

The periodic table is A categorization of elements by chemical characteristics A glossary of elements A table of atoms A table for earth substances

A categorization of elements by chemical characteristics

In true stress-strain curves, the stress is calculated using which area of specimen?

Actual

Metals can be strengthened by ________ . All of them Mechanical working strengthening Precipitation hardening Quench hardening Solid solution strengthening

All

Which of the following is a property of strong bonds, such as ionic bonding or covalent bonding, in ceramics? Chemical inertness High hardness Electron insulation

All

NDT can be used in _____ ? sheet Castings All of them Weldments Strip Extrusions

All of them

Which of the following is a physical property? Hardness Microstructure Color Composition

Color

An alloy is ________. molecules composed of two elements Composed of two or more elements Composed of two electrons Composed of two or more atoms

Composed of two or more elements

Which one is a chemical property? Toughness Reflectance Composition All of them Strength Thermal Expansion

Composition

Alloy is ______ . None of the answer is correct Nonmetal Mixture Compound

Compound

Which of the following is a mixture? Fe Proton Carbon Concrete

Concrete

Which of the following is NOT a thermal property. Specific heat Thermal expansion Elastic modulus Thermal conductivity

Elastic modulus

What determines the rate at which current flows through a per unit cross section and per unit length. Ampere rate Inductance Electricity resistivity Potential resistivity

Electricity resistivity

What is the formula to calculate stress?

F/A

A value of "0" in strain hardening exponent means that a material is a perfectly elastic solid.

False

An atom is the smallest part of a compound that retains the properties of that compound T or F

False

As the tester continues to pull the sample, the material continues to work harder and gets stronger; at the same time the cross-sectional area of the sample begins to rapidly increase.

False

Creep is used to rate the resistance of a material to elastic deformation under sustained load.

False

Elastic Modulus, Modulus of Elasticity, and Young's Modulus are all dissimilar properties of the material.

False

Fourier's law are usually used for calculating Thermal Expansion.

False

Glasses and plastics often have a crystalline structure.

False

Inorganic materials are usually derived from living things.

False

Modulus of Elasticity and Modulus of Elasticity in Shear are the same property.

False

Modulus of elasticity is the measure of a material's toughness.

False

Necking begins before the ultimate strength point.

False

Petroleum products, crude oil, plants, and animals are inorganic materials.

False

Precipitation hardening is used to strengthen many ferrous metals.

False

Strength is defined by hardness

False

Stress concentration factors cannot be applied to loadings such as tension, bending, and torsion.

False

Tensile limit is the point at which the deformation of the material transitions from elastic deformation to plastic deformation

False

The units of strain is psi.

False

Toughness is the ability of a material to release energy before fracturing.

False

Yield strength is typically measured in ft/sec

False

Percentage of Elongation and Bend Radius falls under the property of _____ ? Strength Formability Durability Toughness Rigidity

Formability

The usual purpose of dye penetrant inspection is to _____ ? Find internal voids Measure density Assess surface wetting Assess surface texture Measure porosity Identify surface cracks

Identify surface cracks