DISCUSSION
The group found that each sample's hardness was affected when subjected to heat treatment with natural aging. It was found that the hardness of the samples decreased a significant amount directly after being removed from the oven because of not fully cooling but the values began to naturally age and the hardness values increased. Artificial aging of the samples proved to be most effective with the samples that were heated, immediately quenched, and then aged for the week after. The two steel samples that were quenched in water after being heated for 30 minutes experienced a larger increase in hardness. The group believes this is because the cooling effect caused the initial softer material to transform to a much harder, stronger material. Some possible sources of error for the natural aging metals could have come from the fact that no data was collected over the weekend and therefore not having a full week. Also, the oven was constantly being opened and closed for the metals that were being artificially aged and this could decreased the temperature from its set 370°F. One final source of error could have been with the sanding and it not being consistently grinded with all of the samples.
CONCLUSIONS
After days of testing the samples the hypothesis was proven to be correct. The natural aging process had the higher from the artificial aging on the materials, and the steel 1075 had the higher hardness value than the aluminum 2024.