Recall Elements in MDSP

Measured in pounds or kips per square inch (psi or ksi).

Stress or unit stress

A ____ is the same as 1000 lb. ( a contraction of kilo-pounds)

Kip

____ means the deformation per unit gage length, (in. per in or mm/)

Strain

____, the highest point on the stress-strain curve. It is the maximum load divided by the original area before straining occurs.

Ultimate stress or tensile strength

____ the stress at which a low or medium carbon steel undergoes a marked elongation without an increase in load.

Yield point (YP)

____ is the stress for a specified deviation from the straight part of the stress-strain curve.

Yield strength

The amount of the ____ is usually 0.2% (0.002 in./in. of strain) for steel, aluminum, and magnesium alloys.

Offset

____ is the maximum stress to which standardized test specimen may be subjected without a permanent deformation.

Elastic limit

____ is defined as the stress at which the stress-strain curve deviates from a straight line.

Proportional limit

____ is the proportionality constant in tension. It is the slope of the straight part of the stress-strain curve. It is a measure of stiffness.

Modulus of elasticity (E)

____ is a number that is divided into a criterion of strength in order to obtai a design criterion.

Factor of safety/ Design factor/ Factor of ignorance

____ is a stress computed from a stress equation.

Computed or nominal stress

____ occurs in some metals, notably certain stainless steel, aluminum, and copper alloys, at ambient temperature after solution heat treatment, the process being one of a constituent precipitating from solid solution. Where used, the consequences, include increased strength and hardness, decreased ductility.

Age hardening or precipitation hardening

Aging at moderately elevated temperature expedites the process and is called ____.

Artificial aging

____ is a substance with metallic properties, composed of two or more elements of which at least one is a metal.

Alloy

____ (in steel) are usually considered to be the metallic elements added for the purpose of modifying the properties.

Alloying elements

____ is the characteristic of exhibiting different properties when tested in different directions (as tensile strength "with the grain" or "across the grain").

Anisotropy

____ is a tendency to fracture without appreciable deformation.

Brittleness

____ is one in which a specimen, supported at both ends as a simple beam, is broken by the impact of a falling pendulum. The energy absorbed in breaking the specimen is a measure of the impact strength of the metal.

Charpy test

____ is brittleness of metals at ordinary or low temperatures.

Cold shortness

____ is the process of deforming a metal plastically at a temperature below the recrystallization temperature and at a rate to produce strain hardening. It reduces ductility.

Cold working

____ is frequently used because it increases strength and machinability, and improves surface finish.

Cold-drawn steel

Commercial amounts of cold working of steel are of the order of ____%.

10-20

____ is the ability of a material to absorb or damp vibrations, which is a process of absorbing kinetic energy of vibration owing to hysteresis. The absorbed energy is eventually dissipated to the surroundings as heat.

Damping capacity

At a particular stress level, ____ is a much better damping material than steel.

Cast iron

____ is a loss of carbon from the surface of steel, occurring during hot rolling, forging, and heat treating, when the surrounding medium reacts with the carbon (as oxygen and carbon combining).

Decarburization

____ is that property that permits permanent deformation before fraction in tension.

Ductility

There is no absolute measure of ductility, but the percentage elongation and the percentage reduction of area are used as indices; the higher these indices, the ____ ductile the material is said to be.

more

____ is the opposite of brittleness, but there is no sharp division line.

Ductility

Elongation greater than 5% in 2-in. gage.

Ductile material

Elongation less than 5% in 2-in. gage.

Brittle material

____ is the ability of a material to be deformed and to return to the original shape.

Elasticity

Stress is proportional to strain only during an ____.

Elastic deformation

____ involves the loss of ductility because of a physical or chemical change of the material.

Embrittlement

____ is that part of the carbon content of steel or iron that is in the form of graphite or temper carbon.

Free carbon

____ is a temper produced in a wire, rod, or tube by cold drawing.

Hard drawn

____ have the same structure at all points.

Homogeneous material

____ consists of randomly oriented iron crystals of different sizes, with other matter in between and is thus not homogeneous.

Steel

____ have the same properties in all directions.

Isotropic materials

Wood has a grain; rolled steel is not ____.

Isotropic

____ is a test in which a specimen, supported at one end as a cantilever beam, is broken by the impact of a falling pendulum. The energy absorbed in breaking the specimen is the measure of the impact strength.

Izod test

____ is steel that has been deoxidized with a strong deoxidizing agent, such as silicon or aluminum, in order to eliminate a reaction between the carbon and oxygen during solidification.

Killed steel

____ is a somewhat indefinite property that refers to the relative ease with which a material can be cut.

Machinability

____ is a material's susceptibility to extreme deformation in rolling or hammering.

Malleability

____ are those that have to do with stress and strain: ultimate strength and percentage elongation, for example.

Mechanical properties

____ is the extension in the vicinity of the fracture of a tensile specimen, expressed as a percentage of the original gage length, as 20% in 2 in.

Percentage elongation

____ is the ability of a metal to be deformed considerably without rupture. In a plastic deformation, the material does not return to its original shape.

Plasticity

____ is the ratio of the lateral strain (contraction) to the longitudinal strain (extension) when the element is loaded with a longitudinal tensile force.

Poisson's ratio

____ is that stress which causes a specified permanent deformation of a material, usually 0.01% or less.

Proof stress

____ is a brittleness in steel when it is red hot.

Red shortness

____ are those not due to applied loads or temperature gradients; they exist for various reasons, as unequal cooling rates, cold working, etc.

Relaxation stresses

____ is incompletely deoxidized steel. Ingots of this steel have a surface layer quite free of slag inclusions and gas pockets, which results in the optimum surface on rolled sheets.

Rimmed steel

____ is the ability to resist deformation. It is measured by the modulus of elasticity in the elastic range; the higher the modulus, the stiffer is the material.

Stiffness

____ is increasing the hardness and strength by plastic deformation at temperatures lower than the recrystallization range.

Strain hardening or work hardening

____ is a condition produced in a non-ferrous metal by mechanical or thermal treatment.

Temper

____ is the capacity of material to withstand a shock load without breaking.

Toughness

____ refers to the results of a transverse bend test, the specimen being mounted as a simple beam.

Transverse strength or rupture modulus

____ is steel that has been hammered, rolled, or drawn in the process of manufacture; it may be plain carbon or alloy steel.

Wrought steel

____ is an operation or combination of operations involving the heating and cooling of metal or an alloy in the solid state for the purpose of altering the properties of the material.

Heat treatment

____ is a change in a metal by which its structure recovers from an unstable or metastable condition that has been produced by quenching or cold working.

Aging or age hardening

____, a comprehensive term, is a heating and slow cooling of a solid metal, usually done to soften it.

Annealing

____ has the same meaning as transformation range.

Critical range

____ is often used to mean tempering, but this usage conflicts with the meaning of the drawing of a material through a die and is to be avoided.

Drawing

____, and ____ process, causes the combined carbon to transform wholly or in part into graphitic or free carbon; it is applied to cast iron, sometimes to high-carbon steel.

Graphitizing and Annealing

____ is the heating of certain steels above the transformation range and then quenching, for the purpose of increasing the hardness. In the general case, it is any process of increasing the hardness of a metal.

Hardening

____ is the heating of an iron-base alloy to some 100°F above the transformation range with subsequent cooling to below that range in still air at room temperature. The purpose is to produce a uniform structure.

Normalizing

____ is any heating and cooling of steel that produces a rounded or globular form of carbide. Typically, it is a prolonged heating at a temperature slightly below the transformation range, usually followed by slow cooling; or, for small objects of high-carbon steel, it may be prolonged heating alternately within and slightly below the transformation range.

Spheroidizing

____ (thermal) is the heating of a metal body to a suitable temperature (generally just below the transformation range for steel, say 1100 - 1200°F) and holding it at that temperature for a suitable time (1 to 3 hours for steel) for the purpose of reducing internal residual stresses.

Stress relieving

____ is a reheating of hardened or normalized steel to a temperature below the transformation range, followed by any desired rate of cooling.

Tempering

____ for ferrous metals is the temperature interval during which austenite is formed during heating; it is also the temperature interval during which austenite disappears during cooling.

Transformation range

____ of a material is the measure of its resistance to indentation, and is one of the most significant properties because, properly interpreted, it says much about the condition of the metal.

Hardness

____ is the load in kilogram divided by the area of the surface of the indentation in square millimetres.

Brinell hardness number (BHN)

____ is the capacity of steel to through-harden when cooled from above its transformation range.

Hardenability

____ of iron base alloys is a process of surface hardening whereby the surface or case is substantially harder than the core or inside metal.

Case hardening

____ is a process of adding carbon to the surface of steel by exposing it to hot carbonaceous solids, liquids, or gases — above the transformation temperature.

Carburizing

____ are the common methods of adding carbon.

Pack or Box Carburizing and Gas Carburizing

In ____ the part is heated in carburizing gases, such as methane, ethane, propane, and CO2.

Gas carburizing

What would be the diameter of the shaft to transmit 10 horsepower if the shaft is to make 150 revolutions per minute?

1.53 or 1 9/16 in

What horsepower would be transmitted by a short shaft, 2 inches in diameter carrying two pulleys closed to the bearings, if the shaft makes 300 revolutions per minute.

63 Hp

What should be the diameter of a power-transmitting shaft to transmit 150 kW at 500 rpm?

81 mm

What power would a short shaft, 50 mm in diameter, transmit at 400 rpm?

60kW

Find the torsional deflection of a solid steel shaft 4 inches in diameter and 48 inches long, subjected to a twisting moment of 24,000 inch-pounds.

0.23°

Find the torsional deflection of the solid steel shaft, 100 mm in diameter and 1300 mm long subjected to a twisting moment of 3 x 10⁶ N-mm. The torsional modulus of elasticity is 80,000 N/mm².

0.285°

Find the diameter of a steel lineshaft to transmit 10 Hp at 150 revolutions per minute with a torsional deflection not exceeding 0.08 degree per foot of length.

2.85 inches

A round bar made from SAE 1025 low carbon steel is to support a direct tension load of 50,000 pounds. Using a factor of safety of 4, and assuming that the stress concentration factor K = 1, a suitable standard diameter is to be determined. Calculations are to be based on a yield strength of 40,000 psi.

2 9/16 inches.

A round steel bar of 300 MPa yield strength, is to withstand a direct tension of 200 kN. Using a safety factor of 4, and assuming that the stress concentration factor K = 1, a suitable diameter is to be determined. Calculations are to be based on a yield strength.

0.06 m

Determine the size for the section of a square bar which is to be held firmly at one end and is to support a load of 3000 pounds at the outer end. The bar is to be 30 inches long and is to be made from SAE 1045 medium carbon steel with a yield point of 60,000 psi. A factor of safety of 3 and a stress concentration factor of 1.3 are to be used.

3 5/16 in.

A lever secured to a 2-inch round shaft by a steel tapered pin (dimension d = 3/8 inch) has a pull of 50 pounds at a 30-inch radius from shaft center. Find S, the unit working stress on the pin.

6770 psi

A lever secured to a 50 mm round shaft by a steel tapered pin (d = 10 mm) has a pull of 200 newtons at a radius of 800 mm. Find S, the working stress on the pin.

40.6 MPa

Find the thickness of metal required in the hemi-spherical end of a cylindrical vessel, 2 feet in diameter, subjected to an internal pressure of 500 pounds per square inch. The material is mild steel and a tensile stress of 10,000 pounds per square inch is allowable.

0.3 in

Find the thickness of metal required in the hemi-spherical end of a cylindrical vessel, 750 mm in diameter, subjected to an internal pressure of 3 newtons/mm². The material is mild steel and a tensile stress of 70 newtons/mm² is allowable.

8.04 mm

If a shaft of 50 mm diameter is to transmit power of 12 kilowatts at a speed of 500 rpm, find the mean diameter of the pin for a material having a safe unit stress of 40 N/mm²

Answer: 12.09 mm

This is the most widely used of all spring materials for small springs operating at temperatures up to about 250°F.

Music Wire, ASTM A228 (0.80-0.95 per cent carbon)

This general-purpose spring steel is commonly used for many types of coil springs where the cost of music wire is prohibitive and in sizes larger than are available in music wire.

Oil-Tempered MB Grade, ASTM A229 (0.60-0.70 per cent carbon)

This grade is used for general-purpose springs where cost is the most important factor. Although increased use in recent years has resulted in improved quality, it is best not to use it where long life and accuracy of loads and deflections are important.

Hard-Drawn MB Grade, ASTM A227 (0.60-0.70 per cent carbon):

These spring steels are used for conditions of high stress, and shock or impact loadings.

Alloy Spring Steels

This very popular spring steel is used under conditions involving higher stresses than those for which the high-carbon spring steels are recommended and is also used where good fatigue strength and endurance are needed.

Chromium Vanadium, ASTM A231

This stainless spring steel is very popular because it has the highest tensile strength and quite uniform properties.

Stainless Type 302, ASTM A313 (18 per cent chromium, 8 per cent nickel):

These are important spring materials because of their good electrical properties combined with their good resistance to corrosion.

Copper-base alloys

This material is the least expensive and has the highest electrical conductivity of the copper-base alloys. It has a low tensile strength and poor spring qualities, but is extensively used in flat stampings and where sharp bends are needed.

Spring Brass, ASTM B 134 (70 per cent copper, 30 per cent zinc)

These are corrosion resistant, withstand both elevated and sub-zero temperatures, and their non-magnetic characteristic makes them useful for such applications as gyroscopes, chronoscopes, and indicating instruments.

Nickel-base alloys