
Thermal Aging and Alloy Hardness
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What happens to metal hardness when you bake alloys for a full day? Some metals get harder with heat treatment. Others start to soften.
You place sheets of three alloys in an oven. One is nickel. One is titanium. One is steel. Each sample sits at a set temperature for 24 hours. You test five temperatures from 200 to 1000 degrees Celsius.
After each round you measure hardness with a Rockwell tester. You discover which alloy keeps its strength the longest.
Hypothesis
The hypothesis is that the alloy’s hardness will increase when aged at higher temperatures.
Method & Materials
You will test the hardness of three different alloys (nickel, titanium, and steel) by aging them at different temperatures. You will measure the hardness of the alloys using a portable Rockwell hardness tester.
You will need a portable Rockwell hardness tester with accessories, a sheet of Nickel alloy (Inconel 6.25), a sheet of Titanium alloy (Ti6A14V), a sheet of steel alloy (1018), sand paper, tap water, and a high temperature dry box oven.
Results
The results showed that the hardness of nickel and steel alloy started to decline after aging them at 800 °C. Titanium alloy hardness started to decline after aging at 1000 °C.
Why do this project?
This science project is interesting because it shows how alloys can be treated to increase their hardness and toughness.
Also Consider
Experiment variations could include testing the maximum aging temperature for different types of alloys, or aging for longer periods of time and comparing the hardness of the alloys.
Full project details
Additional information and source material for this project are available below.Related videos
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
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