Procedure

1. For this science fair project, the independent variable is the aging temperature and type of alloy used – nickel alloy, titanium alloy and steel. The dependent variable is the hardness of the alloys after the thermal aging. This is determined by measuring the hardness using the portable Rockwell hardness tester. The constants (control variables) are the thickness of the alloy plates, the aging period and the room temperature.

2. The 3 types of alloys are washed and cleaned. Any oxidization or impurities are removed using sand paper.

3. The dry box oven is set to a temperature of 200°C and it is turned on. Once the temperature has reached the set level, the 3 types of alloy plates are placed inside the oven. The timer is set for 24 hours and the alloys are left to age.

4. After the 24 hours of aging, the oven is turned off, and the alloy plates are allowed to cool down to room temperature. After the plates have cooled down, the hardness of the alloy plates is tested using the portable Rockwell hardness tester. The value of their hardness is recorded in the table given below.

5. Procedures 3 and 4 are repeated by setting the oven temperatures at 400°C, 600°C, 800°C and 1000°C. The aging period is still 24 hours. After allowing the plates to cool down, the hardness of the alloy plates is tested with the portable Rockwell hardness tester and the measured values are recorded in the table given below.

Access to a hardware supplier or your school’s laboratory supplier. You will also need a Rockwell hardness tester and a high temperature dry box.

Safety concerns:

Ensure that the experiment is conducted in a properly equipped laboratory, under the supervision of your science teacher. Hot metal samples need to be handled with the use of proper equipment and protective gear.