Hardness Testing Lab Report

1932 Words Dec 3rd, 2012 8 Pages

The purpose of the following experiments is to study the hardness of different types of materials, and to understand the significance of this property in materials. The materials and the aforesaid property have significant use in civil engineering.
Hardness is defined as a measure of a material’s resistance to localised plastic deformation (i.e. small dents or scratches).
As said above, a variety of metal alloys were used in the experiments to understand how each of these metals is characterised as a hard metal and to compare the hardness of different metal alloys. A study of how the molecular structure and the carbon content affects the hardness of each metal alloy used is also done during the course of the experiment.
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We used a mild steel specimen and a carbon steel specimen for this experiment. 2. We placed the specimen on the stand. 3. We then moved the pressure lever up and down repeatedly to apply pressure into the hydraulic cylinder, until the pressure gauge showed a value of 1000. 4. An indentation was then made on the surface of the specimen. 5. We then used an indentation magnification viewer with a scale on the lens to measure the indentation on the specimen, and thus determine the Brinell Hardness value. 6. We conducted the test three times for each specimen. 7. The data is recorded in Tables 3a and 3b.

Table 3a Hardness values for the mild steel specimen Diameter of indentation (cm) | 3.2 | 3.15 | 3.2 | Brinell’s Hardness, HB | 121 | 125 | 121 | Vicker’s Hardness, HV | 130 | 130 | 130 |

Table 3b Hardness values for the carbon steel specimen Diameter of indentation (cm) | 3.0 | 3.0 | 3.0 | Brinell’s Hardness, HB | 138 | 138 | 138 | Vicker’s Hardness, HV | 141 | 141 | 141 |


4.5.4 Experimental Procedure

1. We placed the specimen on the stand. 2. The hammer was then released from the hold. 3. The hammer swung and made an impact with the specimen. 4. We then recorded the value of the energy expended due to the impact. 5. The data is recorded in Table 4. 6. The result of the impact on the specimen is shown in Figures 4a and 4b.

Figure 4a Mild steel specimen Figure 4b

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