Materials and Processes Flashcards
Content in chapters 7, 10, and 11 for this course
Define NDI
Nondestructive inspection
Define NDT
Nondestructive testing
What is the objective of NDI/NDT?
To determine the airworthiness of a component without damaging or rendering it unairworthy.
What is liquid penetrant inspection?
A nondestructive test for defects open to the surface in parts made of any nonporous material.
What are the two types of dye used in liquid penetrant tests?
Visible and flourescent
What is in a visible penetrant kit?
Dye penetrant, dye remover emulsifier, and developer.
What are the steps for performing a penetrant inspection?
- Clean the surface thoroughly.
- Apply penetrant.
- Remove penetrant with remover emulsifier or cleaner.
- Dry the part.
- Apply the developer.
- Inspect and interpret results.
What can cause false indications in a liquid penetrant inspection?
Accumulations of unwashed penetrant or where parts press fit to each other.
What are eddy current inspections used for?
Detect surface cracks, pits, subsurface cracks, corrosion on inner surfaces, and to determine alloy and heat-treat condition.
What is ultrasonic inspection?
A NDI technique that uses sound energy moving through the test specimen to detect flaws.
What are the two basic methods used for ultrasonic inspection?
Immersion testing and contact testing.
Describe the immersion testing method used in ultrasonic inspection.
The part under examination and the search uni are completely immersed in a liquid couplant, such as water or other suitable fluids.
Describe the contact testing method used in ultrasonic inspection.
The part under examination and the search unit are coupled with a viscous material, liquid, or a paste that wets both the face of the search unit and the material under examination.
What are the three basic ultrasonic inspection methods?
Pulse echo, through transmission, and resonance
How does the pulse echo ultrasonic inspection method detect flaws in a material?
Flaws are detected by measuring the amplitude of signals reflected and the time required for these signals to travel between specific surfaces and the discontinuity.
How does the through transmission ultrasonic inspection method detect flaws in a material?
Through transmission inspection uses two transducers, one to generate the pulse and another placed on the opposite surface to receive it.
What is the resonance ultrasonic inspection method?
The resonance method is used principally for thickness measurements when the two sides of the materal being tested are smooth and parallel and the backside is inaccessible.
What is magnetic particle inspection?
A method of detecting invisible cracks and other defects in ferromagnetic materials.
Where in a part is magnetic particle inspection able to detect defects?
On or near the surface.
What are the two magnetizing operations used in magnetic particle inspection?
Circular magnetization and longitudinal magnetization.
Why are two separate magnetizing operations required for magnetic particle inspections?
To locate a defect in a part it is essential that the magnetic lines of force pass approximately perpendicular to the defect.
What types of plating can interfere with magnetic particle inspection?
Chromium and nickel plating generally do not interfere with indications of cracks open to the surface of the base metal, but prevent indications of fine discontinuities, such as inclusions.
What are the two methods used in magnetic particle inspection?
Continuous inspection method and residual inspection method
What inspection method is preferred for a magnetic particle inspection? Why?
Continous inspection method; the continous inspection method provides greater sensitivity than the residual inspection method.
What is the continuous inspection method when referring to magnetic particle inspection?
A part is magnetized and the indicating medium is applied while the magnetizing force is maintained.
What is the residual inspection method when referring to magnetic particle inspection?
A part is magnetized and the indicating medium is applied after the magnetizing force has been removed.
What are the principal distinguishing features of indications?
Shape, buildup, width, and sharpness of outline.
Define SAE
Society of Automotive Engineers
Define AISI
American Iron and Steel Institute
How is the thickness of sheet metal measured?
Thousandths of an inch.
What is considered low carbon steel?
Steel containing carbon in percentages ranging from 0.10 to 0.30 percent.
What is considered medium carbon steel?
Steel containing carbon in percentages ranging from 0.30 to 0.50 percent.
What is considered high carbon steel?
Steel containing carbon in percentages ranging from 0.50 to 1.05 percent.
What property changes occur when nickel is added to steel?
Nickel increases the hardness, tensile strength, and elastic limit of steel without appreciably decreasing the ductility.
What property changes occur when chromium is added to steel?
Chromium increases the hardness, strength, adds corrosion-resistant properties, and is particularly adaptable for heat-treated forgings.
What is the corrosion resistant steel most often used in aircraft construction known as and why?
18-8 steel; its content is 18 percent chromium and 8 percent nickel.
What is Inconel?
A nickel-chromium-iron alloy closely resembling stainless steel.
What are nonferrous aircraft metals?
All metals that have elements other than iron as its base or principal constituent.
What are the two general classes of aluminum?
Casting alloys (those suitable for casting in sand, permanent mold, or die castings). Wrought alloys (those which may be shaped by rolling, drawing, or forging).
What class of aluminum alloys are used most in aircraft construction?
Wrought alloys; being used for stringers, bulkheads, skin, rivets, and extruded sections.
Describe how the four-digit index system for wrought aluminum alloys works.
The first digit of a designation indicates the alloy type. The second digit indicates specific alloy modifications. The last two digits are used to indicate the hundredths of 1 percent above the original 99 percent designated by the first digit.
Examples: 1100 - 99.00% pure aluminum with one control over individual impurities. 1130 - 99.30% pure aluminum with one control over individual impurities. 1275 - 99.75% pure aluminum with two controls over individual impurities.
What are the three distinct groups used when designating wrought aluminum alloys?
The 1xxx group, the 2xxx through 8xxx group, and the 9xxx group (which is currently unused).
What is the major alloying element used in the formation of wrought aluminum designated as part of the 2xxx group?
Copper