Engineering Lab Report Sample, Master's Student Essay

1796 Words Jun 16th, 2013 8 Pages
Precipitation hardening in 2024 Aluminum
Lab Report

Abstract “Age or Precipitation Hardening” effects on the 2024 Aluminum sample (Al-4%Cu) was investigated by conducting two sets of experiments on 5 samples. In the first experiment, 4 of the samples were artificially aged, and in the second experiment, only one of the 5 samples were naturally aged. In conclusion, it is concluded that the hardness of the samples is directly affected by the time and the temperature of the age hardening, so as the samples are age hardened longer and in a higher temperature, the hardness of them increases accordingly. Description of theory Age or Precipitation hardening is a widely used heat treatment method that is done to raise the strength (including
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Hardness Vs. Time (Naturally Aged, Sample #1)
75 70 65

HARDNESS (HRB)

60 55

50
45 40 35 30 25 0 20 40 60 80 100 120 140 160 180 AGING TIME(HOURS)

Fig 2: Hardness vs. time (Naturally Aged Sample #1)

In the artificially aged samples, generally speaking, all the samples eventually get back to their original hardness they had before annealing, which indicates the occurrence of precipitation hardening in the material. And in comparison to the naturally aged sample, the speed of precipitation occurred in the sample, is increased dramatically, due to the faster diffusion of thermally activated precipitating Beta phase into the matrix of the Alpha Phase.

5

The sample #5, 30 min heat treatment of 190 °C, increases its hardness dramatically to 64.53HRB. Having the same hardness result for both samples shows that 30 min of artificial age hardening is roughly what 1 day naturally age hardening does. In the sample #3, the same phenomenon of precipitation is observed ending the

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