Uji Impact Metode Charpy

Summary

The video demonstrates a standardized impact testing procedure using a specimen with a V-shaped notch. The process begins with the specimen positioned in a testing machine, where a pendulum swings down to strike it, absorbing energy. The absorbed energy, measured in joules, indicates the specimen's notch impact energy. The results reveal that the specimen exhibits minimal plastic deformation and a brittle fracture surface, highlighting its limited ability to absorb energy. This test exemplifies the relationship between potential energy and the material's response, particularly focusing on the effects of strain aging.

Takeaways

• 😀 The test specimen is machined to a standardized size and shape, featuring a characteristic V-shaped notch.
• 😀 The specimen is placed on a support in the testing machine and adjusted for accurate positioning.
• 😀 The test begins by releasing a pendulum that swings downwards to strike the specimen with its rounded hammer.
• 😀 The specimen absorbs some of the pendulum's energy, resulting in the pendulum not reaching its full height on the opposite side.
• 😀 The energy absorbed by the specimen is measured as notch impact energy, expressed in joules.
• 😀 The initial potential energy of the pendulum is determined by the mass of the hammer, gravitational acceleration, and starting height.
• 😀 After impact, the pendulum's energy is recalculated based on the height it reaches after striking the specimen.
• 😀 The difference between the initial and final potential energy represents the notch impact energy absorbed by the specimen.
• 😀 The first specimen tested shows minimal plastic deformation and a flat, slightly glittering fracture surface.
• 😀 This indicates that the steel exhibits brittle behavior and can absorb only small amounts of notch impact energy due to strain aging.

Q & A

What is the purpose of the test specimen described in the transcript?

The test specimen is machined to a standardized size and shape with a characteristic v-shaped notch to measure its notch impact energy.

How is the test specimen prepared for testing?

The tester places the specimen on a support in the lower part of the machine and adjusts its position with a centering device before starting the test.

What happens to the pendulum when it is released?

When the pendulum is released, it swings downwards and hits the specimen with its rounded hammer, transferring part of its energy to the specimen.

How is the energy absorbed by the specimen measured?

The energy absorbed by the specimen is measured by reading the position of the drag indicated on the decatur after the pendulum has struck the specimen.

What does the notch impact energy correspond to?

The notch impact energy corresponds to the difference between the potential energy at the starting height and the potential energy at the first reversal point after the impact.

What are the potential energy formulas mentioned in the transcript?

The potential energy is given by the formulas: for starting position, it is M * G * H, and at the first reversal point, it is M * G * h, where M is mass, G is gravitational acceleration, and H and h are the respective heights.

What type of fracture surface is observed in the specimen after the test?

The specimen shows a mostly flat, slightly glittering fracture surface, indicating minimal plastic deformation and predominantly brittle behavior.

What does a low notch impact energy value indicate about the steel?

A low notch impact energy value indicates that the steel is only able to absorb small amounts of energy, suggesting brittle behavior rather than ductile.

What effect is mentioned that contributes to the specimen's behavior?

The strain aging effect is mentioned, which contributes to the brittle behavior of the steel, affecting its energy absorption capacity.

Why is the test significant for understanding material properties?

The test is significant because it helps determine the toughness and brittleness of materials, which are crucial for applications where impact resistance is important.