Hardness Tests: Impact of Charpy and Fatigue

Determine the average fracture energy for each materials, and fill it in the corresponding cell in Table 1.1.6. Discuss the difference in the fracture energy of the four different materials.

Discuss the difference in fracture energy within the same material (for example, the changes in energy for Al).1.8. Table 2: Fracture Energy Data for a Specific Material at Different TemperaturesTemperature (°C) Impact Energy (J)100 89.375 88.650 87.625 85.40 82.9-25 78.9-50 73.1-65 66.0-75 59.3-85 47.9-100 43.3-125 29.3-150 27.1-175 25.01.9. Fracture Energy vs. Temperature CurvePlot the curve1. Transition TemperatureDetermine the transition temperature from the plot.

1.11. What is the difference between strength and toughness? Fatigue Test Data Stress (ksi) Cycles to Failure (x102)56.7 27155.4 40453.4 83652.8 153751.0 263949.5 400048.3 540047.5 135892.

The reason for this examination is to measure the perpetual profundity of the indentation that is applied by a force on the indenter, therefore to look at and think about the hardness of various metals relying upon the profundity of the space. Experimental methodsIn the wake of setting the machine correctly, we raise the specimen to such an extent that it become in contact with the indenter by turning the big screw to such an extent that the center gage becomes vertical and modify the little screw to set the dial to zero.

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After that we press the switch and start the test. The last position of the dial pointer gives Rockwell hardness number which is straightforwardly identified with the profundity on indentation. At that point we take the recorded values legitimately from the screen.

At that point we do a similar technique for the remaining materials. Main resultsAfter we are done doing the experiment, we recorded the values of the trail given by the machine.

We calculated the average and we found out that material D has an average of 93.03 which is the highest while material A has an average of 70.54 which is the lowest. This proves that material D is the hardest one and material A is the weakest one. The increasing order of hardness was D > C >B >A which is proved in the table below.Table 4. Hardness ValuesRockwell Hardness (HRC)Trial Average Standard DeviationMaterial 1 2 3 4 5 6 A 70.19 69.75 70.68 71.03 70.80 70.79 70.54 0.47B 84.41 84.08 84.58 79.90 84.25 84.91 83.68 1.88C 86.62 86.95 87.43 87.53 82.34 87.52 86.39 2.02D 91.35 91.91 92.02 91.72 98.89 92.33 93.03 2.883.5.

Determine the average and the standard deviation of each sample in the Table 4. Write the values in the corresponding cells.Average =16Trail6=91.35+91.91+92.02+91.72+98.89+92.336=93.03 HRC.Standard Deviation = (T-Tav)^(2)6-1For specimen D: Standard Deviation = 91.35-93.032++(92.33-93.03)^(2)6-1=2.88 HRC. Discuss two factors that explain the differences in the measurements within each sample. Surface impurities: They could be because of a previous indent in the surface of the material that is utilized which could straightforwardly influence the estimations and recorded values. Cleanliness: The surface could have dust on it which is a boundary and could change the estimation results.

What other techniques could be used to get much more accurate hardness measurements?The other indentation techniques which give a better result rather than on a macro-scale (HRC) we shall use:Vickers Hardness Test: we are talking about micro-scale.

Nano-Indenter: we are talking about Nano-scale.This test is more accurate than the previous ones.3.8. Why some materials are harder than others?Some materials are harder than others because of the presence of the grain boundaries. The case is totally different in metals because of the rolling process and how atoms are aligned. Therefore, the more grain boundaries exist the more hardness we get. Moreover, some metals are mixture like iron, nickel etc... which definitely makes the material more harder.