Steel is normalized by heating above the critical temperature, soaking, and then air cooling. This process increases the strength of the steel, refines the grain, and homogenizes the structure. An experiment is performed to determine the effect of temperature and heat treatment time on the strength of normalized steel. Two temperatures and three times are selected. The experiment is performed by heating the oven to a randomly selected temperature and inserting three specimens. After 10 minutes one specimen is removed, after 20 minutes the second is removed, and after 30 minutes the final specimen is removed. Then the temperature is changed to the other level and the process is repeated. Four shifts are required to collect the data, which are shown below. Analyze the data and draw conclusions, assuming both factors are fixed.

Transcribed Image Text:

Temperature, °F Shift Time, minutes 1500 1600 10 63 89 1 20 54 91 30 61 62 10 50 80 20 52 72 30 59 69 10 48 73 3 20 74 81 30 71 69 10 54 88 20 48 92 30 59 64 2.