OBJECTIVE
Our primary aim is to measure the Rockwell Hardness values of materials and estimate ultimate tensile strengths by the aid of conversion tables. We will also focus on age hardening, the info on which can be found in the last part of this experiment sheet.
2. HARDNESS TESTING THEORY
Hardness is usually defined as the resistance of a material to plastic penetration of its surface. There are three main types of tests used to determine hardness:
• Scratch tests are the simplest form of hardness tests. In this test, various materials are rated on their ability to scratch one another. Mohs hardness test is of this type. This test is used mainly in mineralogy.
• In Dynamic Hardness tests, an object of standard mass and dimensions is bounced back from a surface after falling by its own weight. The height of the rebound is indicated. Shore hardness is measured by this method.
• Static Indentation tests are based on the relation of indentation of the specimen by a penetrator under a given load. The relationship of total test force to the area or depth of indentation provides a measure of hardness. The Rockwell, Brinell, Knoop, Vickers, and ultrasonic hardness tests are of this type.
For engineering purposes, mostly the static indentation tests are used.
http://web1.boun.edu.tr/ercanbalikci/hardness.pdf
No comments:
Post a Comment