AIRCRAFT STRURAL MATERIALS (METALLIC) Flashcards
ABILITY OF A MATYERIAL TO WITHSTAND TENSION
TENSILE STRENGTH
ABILITY OF A MATERIAL TO RESIST DEFORMATION
YIELD STRENGTH
ABILITY OF A JOINT TO WITHSTAND ANY FORM OF CRUSHING OR DISTORTION
BEARING STREMNGTH
ABILITY TO RESIST CUTTING, PENETRATION, OR ABRASION
HARDNESS
MEATALS ARE HARDENED THROUGH?
HEAT-TREATING OR WORK-HARDENING
METALS ARE SOFTENED BY A PROCESS CALLED?
ANNEALING
ABILITY TO BE BENT, FORMED, OR SHAPE WITHOUT BREAKING
MALLEABILITY
TENDENCY OF A MATERIAL TO BREAK
BRITTLENESS
Enables a metal to carry heat or electricity.
CONDUCTIVITY
Property of a metal to expand when heated and shrink when cooled. The amount of expansion or contraction is predictable at specific temperatures
THERMAL EXPSION
Metal’s tendency to return to its original shape after normal stretching and bending.
ELASTICITY
Point beyond which the metal does not return to its original shape after a deforming force is removed.
ELASTIC LIMIT
Metal’s ability to resist tearing or breaking when it is bent or stretched.
TOUGHNESS
Formed by physically working the metal into shape.
WROUGHT OBJECTS
Ability of metal to be joined by heating and melting.
FUSIBILITY
Material’s mass per unit volume.
DENSITY
Formed by pouring molten metal into molds.
CAST OBJECTS
Process of forming metal at an elevated temperature when it is in its annealed, or soft condition.
HOT WORKING
consists of forming hot metal ingots with rollers to form sheets, bars, and beams.
ROLLING
worked at temperatures above its critical range.
FORGING
Used to form large and heavy parts.
PRESSING
Hammering process whereby a hot ingot is placed between a pair of formed dies in a machine called a drop hammer and a weight of several tons is dropped on the upper die.
DROP FORGING
Type of forging that is usually used on small parts because it requires a metalworker to physically hammer a piece of metal into its finished shape.
HAMMERING
Performed well below a metal’s critical temperature.
Strain hardens the worked metal, increasing its strength and hardness but decreasing ductility.
COLD-WORKING
Used in making seamless tubing, wire, streamlined tie rods, and other forms of stock.
cold drawing
rolling of metal at room temperature to its approximate size.
COLD ROLLING
Process of forging metal through a die which imparts a required cross-section to the metal.
extrusion
Metals which have elements other than iron as their base.
NON-FERROUS METALS
1XXX
Offers high corrosion resistance, excellent thermal and electric properties but very low in strength.
ALUMINUM
2XXX
Metallic changes take place in the resultant alloy’s grain structure. However, it is susceptible to intergranular corrosion when improperly heat-treated.
COPPER
3XXX
Non heat treatable. Offers moderate strength and has good working characteristics.
MANGANESE
4XXX
Lowers a metal’s melting temperature. This results in an alloy that works well for welding and brazing.
SILICON
5XXX
Good welding and corrosion-resistance characteristics. However, if the metal is exposed to high temperatures or excessive cold working, its susceptibility to corrosion increases.
MAGNESIUM
6XXX
Medium strength with good forming and corrosion-resistance properties.
MAGNESIUM AND SILICON
7XXX
Used when parts require more strength and little forming. This alloy is very hard and is difficult to bend.
ZINC
8XXX
OTHER ELEMENTS
represents a specific alloy modification.
SECOND NUMBER
Pure aluminum coating that is rolled on to the surface of heat-treated aluminum alloy.
The thickness of this coating is approximately 5% of the alloy’s thickness on each side.
CLAD ALUMINUM ALLOY
Series of operations involving the heating and cooling of metals in their solid state.
HEAT TREATMENT
Process of heating certain aluminum alloys to allow the alloying element to mix with the base metal. Metal is heated in either a molten sodium or potassium nitrate bath or in a hot-air furnace to a temperature just below its melting point.
SOLUTION HEAT TREATMENT
Heat-treatable aluminum alloys are comparatively soft when first removed from a quench.
PRECIPITATION HEAT TREATMENT
When alloy is allowed to cool at room temperature, it is referred to as
NATURAL AGING
Process that softens a metal and decrease internal stress.
ANNEALING
T
SOLUTION HEAT TREATED
T2
ANNEALED(CAST)
T3
SHT STRAIN HARDENED
T4
SHT NATURALLY AGED
T5
ARTIFICIALLY AFED
T6
SHT ARTIFICIALLY AGED
T7
SHT STABILIZED
T8
SHT
STRAIN HARDENED, ARTIFICIALLY AGED
T9
SHT,
ARTIFICIALLY AGED, STRAIN HARDENED
T10
ARTIFICIALLY AGED, STRAIN HARDENED
Material which has been previously heat-treated can generally be reheat treated any number of times. As an example, rivets made of 2017 or 2024 are extremely hard and typically receive several reheat treatments to make them soft enough to drive.
REHEAT TREATMENT
Both heat-treatable and nonheat-treatable aluminum alloys can be strengthened and hardened through strain hardening, also referred to as cold working or work hardening. The mechanical working can consist of rolling, drawing, or pressing.
STRAIN HARDENING
F
FABRICATED
O
ANNEALED
H
STRAIN HARDENED
H1
STRAIN HARDENED ONLY
H2
SH, PARTIALLY ANNEALED
H3
SH, STABILIZED
H4
sh and baked
HX2
QUARTERED HARD
HX4
HALF HARD
HX6
THREE-QUARTERED HARD
HX8
FULL HARD
HX9
EXTRA HARD
Used for castings and in its wrought form is available in sheets, bars, tubing, and extrusions.
MAGNESIUM AND ALLOYS
Light weight metals with very high strength. They also have excellent corrosion resistance characteristics. However, since the metal is sensitive to both nitrogen and oxygen, it must be converted to titanium dioxide with chlorine gas.
TITANIUM AND ALLOYS
Medium strengths of 120 KSI to 150 KSI, can be welded and used in forgings.
ALPHA
Medium strength in the annealed condition and much greater strength when heat treated. Not weldable.
ALPHA-BETA
Medium strength, excellent forming characteristics. Can be heat-treated to a very high strength.
BETA
68% nickel, 29% copper
MONEL
80% nickel, 14% chromium
INCONEL
COPPER+ZINC
BRASS
COPPER+TIN
BRONZE
97% copper, 2% beryllium
BERRYLIUM COPPER
Any alloy containing iron as its chief constituent.
FERROUS METALS
Fairly soft, malleable, and ductile.
IRON
Pig iron is re-melted in a special furnace.
STEEL
SAE-1XXX
When mixed with iron, compounds of iron carbides called cementite form.
CARBON
SAE-2XXX
Adds strength and hardness to steel and increases its yield strength. Used in producing aircraft hardware such as bolts, nuts, rod ends, and pins.
NICKEL
SAE-3XXX
Nickel toughens steel, and chromium hardens it. Used for forged and machined parts requiring high strength, ductility, shock resistance, and toughness.
NICKEL CHROMIUM
SAE-4XXX
Reduces the grain size of steel and increases both its impact strength and elastic limit. Extremely wear resistant and possess a great deal of fatigue strength.
MOLYBDENUM
SAE-5XXX
Increase strength and hardness as well as improve its wear and corrosion resistance. Used in balls and rollers of antifriction bearings.
CHROMIUM
SAE-6XXX
CHROMIUM VANADIUM
SAE-7XXX
Extremely high melting point, typically used for breaker contacts in magnetos and for high-speed cutting tools.
TUNGSTEN
SAE-8XXX
NICKEL CHROMIUM VANADIUM
SAE-9XXX
SILICON AND MANGANESE
0.10-0.30 - Easily welded and machines readily, does not accept heat treatment.
LOW
0.30-0.50 - Accept heat treatment, adaptable for machining or forging
MEDIUM
0.50 - 1.05 - Used in springs, files, and some cutting fools
HIGH
Causes steel to be brittle when rolled or forged and must be removed in the refining process.
SULFUR
Acts as a hardener. It also improves ductility.
SILICON
Raises the yield strength of steel. However, no more than 0.05% ____
PHOSPHOROUS
toughness and wear resistance make it a good material for engine cylinders and other highly stressed engine parts.
CHROME-MOLYBDENUM
Corrosion resistance steels that contain large amount of chromium and nickel. Suited for high temperature applications such as firewalls and exhaust system components.
STAINLESS STEEL
When these steels are heated to a temperature above their critical range, a structure known as austenite forms. Austenite is a solid solution of pearlite. Hardened only by coldworking while heat treatment serves only to anneal them.
AUSTENTIC
No carbon and do not respond to heat treatment.
FERRITIC
Extremely hard if allowed to cool rapidly by quenching from an elevated temperature. They are magnetic.
MARTENSITIC
Increase both ultimate tensile strength and toughness. Most wrenches and ball bearings are made of chromium-vanadium steel.
VANADIUM
Alpha solid solution of iron containing some carbon and exists at temperatures below the lower critical temperature.
FERRITE
Above the lower critical temperature, the steel begins to turn into austenite, which consists of gamma iron containing carbon.
AUSTENTITE
Softens steel and relieves internal stress. It is heated to about 50F above its critical temperature, soaked for a specified time, then cooled. Soaking time is typically around one hour per inch of material thickness.
ANNEALING
The processes of forging, welding, or machining usually leave stresses within steel that could lead to failure. These stresses are relieved in ferrous metals. Heated to about 100F above its upper critical temperature and held there until the metal is uniformly heat soaked. The steel is in then removed from the furnace and allowed to cool in still air.
NORMALIZING
It is heated above its critical temperature so carbon can disperse uniformly in the iron matrix. Once this occurs, the alloy is cooled rapidly by quenching it in water, oil, or brine.
HARDENING
provides the slowest quench
OIL
provides the MOST RAPID quench
BRINE
Reduces the undesirable qualities of martensitic steel. It is heated to a level considerably below its critical temperature. It is then allowed to cool to room temperature in still air.
TEMPERING
Certain components in aircraft engines and landing gear systems require metal with hard, durable bearing surfaces and core material that remains tough accomplished through
CASE HARDENING
Forms a thin layer of high-carbon steels on the exterior of low-carbon steel.
CARBURIZING
Enclosing the metal in a fire-clay container and packing it with a carbon-rich material such as charcoal.
PACK
Carbon monoxide gas combines with gamma iron and forms a high-carbon surface.
GAS
Produces a high-carbon surface when a part is heated in a molten bath of sodium cyanide or barium cyanide.
LIQUID
Uses a hydraulic force to impress a spherical penetrator into the surface of a sample. The amount of force used is approximately 3,000 kg for steel, and 500 kg for nonferrous metals.
BRINELL HARDNESS TEST
First hardened, tempered, and then ground to its finished dimensions before it is case hardened. Heated to a temperature of approximately 1000F, and then surrounded by ammonia gas (NH3).
Engine crankshafts and cylinder walls are commonly nitrided for increased wear resistance.
NITRIDING
Measures the depth to which the penetrator sinks into the material. Uses a conical diamond, a 1/16 inch ball, and a ⅛ inch ball. There are also three major loads: 60 kg, 100 kg, and 150 kg.
ROCKWELL HARDNESS TEST
Formed from ingots of aluminum alloy that are passed through a series of rollers until the metal is reduced to a desired thickness.
SHEET METAL GRAIN
A radius is measured on the inside of a bend and is generally measured in fractions.
To prevent cracks, a minimum _________ is recommended for different types of alloys and metal thickness
BEND RADIUS
When bending a piece of metal around a radius, the metal on the outside of the bend stretches, while the metal toward the inside tends to compress or shrink. The line along which this occurs is called the
NEUTRAL AXIS
Used to designate the dimensions of a piece of metal on a drawing or layout pattern.
MOLD LINE
Point where two mold lines intersect in a bend.
MOLD POINT
Designate the location where the sheet metal begins to form around the bend radius.
BENT TANGENT LINE
Distance between the mold line and the bend tangent line inside the bend area.
SETBACK
When a sheet metal structure is built up, there are often locations where the metal is stacked into multiple layers where the parts are joined together. In order for the sheet metal pieces to be flat against the skin and yet have one on top of the other at the joining intersection.
JOGGLING
Allowable damage covered in the SRM
COSMETIC
Repairable damage covered in the SRM
Specific damage requires manufacturers approval
STRUCTURAL
