Uji Keras

Summary

This video provides a comprehensive guide to hardness testing methods used in material science, specifically Brinell, Rockwell, and Vickers tests. It covers the preparation and testing processes for various materials like steel and aluminum, demonstrating the operation of different testing machines and the principles behind each method. Viewers learn how to conduct tests, apply loads, and measure the resulting indentations. The video also explains the importance of accurate measurements, including the use of microscopes for precise reading of indentation sizes, and highlights the formulas used to calculate hardness values.

Takeaways

• 😀 The script demonstrates various material hardness testing methods, including Brinell, Rockwell, Vickers, and micro-Vickers.
• 😀 Brinell hardness testing uses a ball indenter to measure the size of an indentation formed on the specimen under a specific load.
• 😀 The Rockwell hardness test determines material hardness based on the depth of indentation, with different indentors and loads for various tests.
• 😀 Rockwell hardness test involves both a minor load (10 kg) and a major load (variable based on test type) to assess material hardness.
• 😀 The script highlights the differences between macro and micro hardness testing, with micro-Vickers testing using a diamond pyramid indenter.
• 😀 In Brinell hardness testing, the diameter of the indentation is measured using a microscope and entered into a formula to calculate hardness.
• 😀 The Brinell hardness number (BHN) depends on the applied force, the indenter diameter, and the indentation size.
• 😀 Rockwell hardness testing offers different scales (e.g., HRB, HRC) based on the indentor type, such as steel balls or diamond cones.
• 😀 The Vickers hardness test uses a diamond pyramid indenter and is calculated based on the diagonal length of the indentation.
• 😀 The micro-Vickers test uses a smaller load (e.g., 500 grams) and is suitable for fine measurements on thin materials or coatings.
• 😀 All hardness tests require careful specimen preparation and accurate measurement of indentations to ensure reliable results.

Q & A

What types of mechanical testing are mentioned in the transcript?

The transcript mentions several types of mechanical testing, including tensile testing, bending testing, hardness testing, and torsion testing.

What are the main differences between the three hardness samples presented?

The three hardness samples are made from different materials: one is made of steel, one is made of aluminum, and the third is a combination of materials with different shapes (round and square). The steel sample has a characteristic appearance with circular cut marks, while the aluminum sample has a different color due to the material's properties.

How does the Brinell hardness test work?

In the Brinell hardness test, a steel ball indentor is pressed into the surface of the material under a specific load. The diameter of the indentation left is then measured, and the hardness value is calculated based on this diameter, the applied force, and the indentor's diameter.

What is the role of the anvil in the Brinell hardness test?

The anvil is used to hold the specimen in place during the test, ensuring that the specimen is properly aligned with the indentor. It also provides the necessary surface for applying the load to the material being tested.

What is the significance of the 187.5 kg load used in the Brinell hardness test?

The 187.5 kg load is the standard weight used in the Brinell hardness test to ensure consistent application of pressure across different samples. This load helps in measuring the material's resistance to indentation.

How is the Rockwell hardness test different from the Brinell test?

The Rockwell hardness test measures the depth of indentation rather than the diameter of the indentation. It uses either a diamond cone or a steel ball as the indentor, depending on the specific type of Rockwell test being performed.

What are the components of a Rockwell hardness testing machine?

A Rockwell hardness testing machine consists of an anvil to hold the specimen, a control knob to apply the load, an indentor (either a steel ball or diamond cone), and a display screen to show the test results.

What is the purpose of minor and major loads in the Rockwell hardness test?

In the Rockwell hardness test, the minor load (typically 10 kg) is applied initially to ensure proper contact between the indentor and the specimen. The major load is then applied to create the indentation, and the hardness is measured based on the depth of the indentation.

What is the Vickers hardness test used for, and how is it performed?

The Vickers hardness test is used to measure the hardness of materials by pressing a diamond pyramid indentor into the surface of the specimen. The length of the diagonals of the indentation is measured, and the hardness is calculated based on the applied force and the size of the indentation.

How is the indentation measured in the Vickers hardness test?

In the Vickers hardness test, the indentation left by the diamond pyramid is measured using a microscope. The diagonals of the indentation are measured, and the hardness value is calculated based on the length of these diagonals and the applied force.