Impact and Hardness Testing

Only available on StudyMode
  • Topic: Tensile strength, Charpy impact test, Rockwell scale
  • Pages : 12 (3169 words )
  • Download(s) : 242
  • Published : September 25, 2011
Open Document
Text Preview
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 were performed, Chavenet’s criterion was applied to process the collected data. Figure (1)

Figure (2)

Figure (3)

Table of Contents
1. Title Page
2. Abstract
3. Table of Contents
4. List of Nomenclature
5. List of Figures and Tables
6. Experimental Apparatus and Procedure
7. Experimental Results
8. Discussion
9. Conclusions
10. References
11. Appendix

List of Nomenclature
Hardness- a measure of a material’s resistance to localized plastic deformation. Toughness-a measure of the amount of energy a material can absorb before fracturing. Minor Load-initial load applied to a specimen in the Rockwell test to eliminate backlash in the load train and cause the indenter to break through slight surface roughness to improve accuracy. Major Load-secondary load applied a specimen that is applied at a prescribed, controlled rate. Impact test-a method to discover a specimen’s toughness.

Chavenet’s Criterion-A method to process the data following Gaussian distribution. Tensile-the ability of a metal to be stretched out and the limit thereof. Tensile Test-a test to determine the reaction of a material to an applied force.

List of Figures and Tables
Figure (1)-photo demonstration of Charpy impact test

Figure (2)-photo demonstration of Rockwell hardness test

Figure(3)-photo of a tensile strength testing machine

Experimental Apparatus and Procedure
Hardness Test-for the hardness test, specimens will be subjected to the Rockwell Harness test. The procedure is as follows:
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. {1} Standard specimen size is .25” thick.

The hardness is read directly from the dial with...
tracking img