Impact and Hardness Testing
Mechanical Testing: Impact and Hardness Testing
ME-3701-02
3rd March 2009
Ke Chen
Abstract This experiment, as may be derived from the title, involves testing multiple metallic specimens to determine their toughness, strength and hardness. The three tests used to determine these characteristics are called the Charpy Impact test, tensile strength test and Rockwell Hardness test. As stated by www.key-to-steel.com {1}, “Charpy impact test method for metallic materials is specified by European EN 10045 standard. This specification defines terms, dimension and tolerances of test pieces, type of the notch (U or V), test force, verification of impact testing machines etc.
The test consists of breaking by one blow from a swinging pendulum, under conditions defined by standard, a test piece notched in the middle and supported at each end. The energy absorbed is determined in joules. This absorbed energy is a measure of the impact strength of the material.” Furthermore, www.flti.com {2} states the following as the proper procedure for conducting the Rockwell Hardness test: “A standard specimen is placed on the surface of the Rockwell Hardness tester. A minor load is applied and the gauge is set to zero. The major load is applied by tripping a lever. After 15 seconds the major load is removed. The specimen is allowed to recover for 15 seconds and then the hardness is read off the dial with the minor load still applied.” The standard specimen for the Rockwell Harness test is 1/4” thick. Finally, www.instron.us {3} shows us that “A tensile test, also known as tension test, is probably the most fundamental type of mechanical test you can perform on material. Tensile tests are simple, relatively inexpensive, and fully standardized. By pulling on something, you will very quickly determine how the material will react to forces being applied in tension. As the material is being pulled, you will find its strength along with how much it will elongate.” Once the three tests
ME-3701-02
3rd March 2009
Ke Chen
Abstract This experiment, as may be derived from the title, involves testing multiple metallic specimens to determine their toughness, strength and hardness. The three tests used to determine these characteristics are called the Charpy Impact test, tensile strength test and Rockwell Hardness test. As stated by www.key-to-steel.com {1}, “Charpy impact test method for metallic materials is specified by European EN 10045 standard. This specification defines terms, dimension and tolerances of test pieces, type of the notch (U or V), test force, verification of impact testing machines etc.
The test consists of breaking by one blow from a swinging pendulum, under conditions defined by standard, a test piece notched in the middle and supported at each end. The energy absorbed is determined in joules. This absorbed energy is a measure of the impact strength of the material.” Furthermore, www.flti.com {2} states the following as the proper procedure for conducting the Rockwell Hardness test: “A standard specimen is placed on the surface of the Rockwell Hardness tester. A minor load is applied and the gauge is set to zero. The major load is applied by tripping a lever. After 15 seconds the major load is removed. The specimen is allowed to recover for 15 seconds and then the hardness is read off the dial with the minor load still applied.” The standard specimen for the Rockwell Harness test is 1/4” thick. Finally, www.instron.us {3} shows us that “A tensile test, also known as tension test, is probably the most fundamental type of mechanical test you can perform on material. Tensile tests are simple, relatively inexpensive, and fully standardized. By pulling on something, you will very quickly determine how the material will react to forces being applied in tension. As the material is being pulled, you will find its strength along with how much it will elongate.” Once the three tests
References: {1}Charpy Impact Test for Metallic Materials. Key to Steel: The World’s Most Comprehensive Steel Database. http://steel.keytometals.com/Articles/Art94.htm {2} Rockwell Hardness: ASTM D785, ISO 2039. Intertek Plastics Technology Laboratories. 1996-2009. http://www.ptli.com/testlopedia/tests/Rockwell-d785.asp {3}Tensile Strength Testing: What is a Tension Test? Instron: Materials Testing Solutions. Instron Worldwide Headquarters, 825 University Ave, Norwood, MA 02062-2643, USA. http://www.instron.us/wa/applications/test_types/tension/default.aspx {4}Tensile Test, Butt Joint, Metal Tensile Test, Tensile Testing Machine. Welding Tecnology Machines. http://www.welding-technology-machines.info/inspection-and-testing-of-welds/tensile-test.htm. Appendix