48 Questions
What does the Rockwell hardness tester measure?
Depth of penetration into the material
How does a Rockwell hardness tester display the depth of penetration?
In Rockwell numbers on a red or a black scale
What type of loads are applied by Rockwell testers during testing?
Minor and major loads
How is the Tensile Strength of ferrous metal tested?
By applying a longitudinal load and plotting load against elongation
What does the Brinell hardness tester measure?
Depth of penetration into the material
How are results displayed by a Rockwell hardness tester different from those displayed by a Brinell hardness tester?
Rockwell numbers on a red or black scale vs. diameter measurements
What are some properties tested for in metallic materials after a heat-treatment process?
Hardness, tensile strength, and impact resistance
What is the purpose of hardness testing in metallic materials?
To assess the material's resistance to deformation
Which two methods are mentioned as the most widely used for hardness measurement in metals?
Brinell and Rockwell methods
What force is used by the Brinell hardness tester to impress a penetrator into the surface of a metal sample?
Hydraulic force
How is the diameter of the impression measured after a metal sample is tested using the Brinell method?
With a special calibrated microscope
Why is testing carried out with a test piece consisting of the same material and thickness of the component that was heat-treated?
To standardize testing conditions and results
What is the purpose of fatigue strength testing?
To establish the stress level at which structural failure will occur
How is fatigue life determined in fatigue strength testing?
By measuring the number of cycles completed
What is the purpose of an airframe fatigue test?
To provide data on premature fatigue damage or wear
How does the Wohler Cantilever bending fatigue machine stress test pieces?
By applying tension and compression once every revolution
What type of load is suspended from the ball race in fatigue strength testing?
Overhung load
Why are aircraft subjected to fatigue tests?
To identify causes of premature fatigue damage
Which impact resistance test uses a cantilevered configuration?
Izod impact test
What type of beam configuration does the Charpy impact test use?
Three-point beam configuration
Which impact testing method is the most common for metals?
Charpy impact test
What shape does the specimen take in the Charpy V-notch technique?
Square cross section
What instrument is used to fracture the specimen in the Charpy V-notch technique?
Pendulum hammer
What happens to the pendulum after striking and fracturing the specimen in the Charpy V-notch test?
It continues its swing up to a maximum final height
What is the primary purpose of testing metallic materials after a heat-treatment process?
To confirm the achievement of desired qualities
Which two methods are mentioned as the most widely used methods for hardness measurement in metals?
Brinell and Rockwell methods
How is the Brinell hardness tester different from the Rockwell hardness tester?
Brinell measures indentation depth while Rockwell measures impression diameter
What property of metals does hardness testing aim to measure?
Strength
Why is it necessary to test a material with a test piece identical to the heat-treated component?
To ensure consistency and accuracy in test results
What is the main role of a Brinell hardness tester in measuring hardness in metallic materials?
To measure indentation depth
What is the purpose of the ball race in fatigue strength testing?
To suspend a load for stress application
What is the main objective of conducting an airframe fatigue test?
To identify premature fatigue damage causes
How does the number of cycles completed relate to fatigue life in fatigue strength testing?
It measures the fatigue resistance of the material
What role does an electric motor play in the Wohler Cantilever bending fatigue machine?
To rotate the test piece under an overhung load
What type of structural failure does fatigue strength testing aim to predict?
Fatigue failure
Why are aircraft subjected to fatigue tests before being certified for operation?
To identify potential structural weaknesses and causes of premature fatigue damage
What is the main difference between the Izod impact test and the Charpy impact test?
The beam configuration used
What is the shape of the specimen used in the Charpy V-notch technique?
Bar with a V-notch
During the Charpy V-notch impact test, what happens to the pendulum after it strikes and fractures the specimen?
Continues its swing
What is released from an initial height to apply the impact load in the Charpy V-notch technique?
Weighted pendulum hammer
Which type of beam configuration is used in the Izod impact test?
Cantilevered
In Charpy V-notch impact testing, what is altered to increase or decrease the impact resistance of a metal?
Angle of the V-notch
What is the key difference between the information provided by a Brinell hardness tester and a Rockwell hardness tester?
The Brinell tester measures the diameter of the impression, while the Rockwell tester measures the depth of penetration.
How does a Rockwell hardness tester display depth of penetration compared to the Brinell hardness tester?
In Rockwell numbers on either a red or a black scale.
What is the primary purpose of tensile strength testing for ferrous metals?
To evaluate how much stretching or pulling force the metal can endure before breaking.
Which type of loads are typically applied during Rockwell hardness testing?
Minor loads followed by major loads.
Why is it essential to plot load against elongation in tensile strength testing?
To evaluate how the metal deforms under stretching forces.
What information does the dial on a Rockwell hardness tester provide?
The depth to which the penetrator sinks into the material.
Learn about the testing of metallic materials after a heat treatment process to ensure desired qualities such as hardness, tensile strength, fatigue strength, and impact resistance. The testing is done with a test piece made of the same material and thickness as the component that underwent the heat treatment.
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