Objective
The objective is to get hands on experience and to actually see how the process of quenching and normalization works. Also, we would be able to observe the difference in the microstructure of each specimen we handle. We would develop a better understanding that the carbon content and the cooling rate can affect the strength and hardness of steel.
Procedure
We first heated two specimens of 1144 steel with a hardness of HRB 96. The cold rolled steel bars were 0.5 inches diameter about 0.5 inches long. The specimens were placed in a furnace at 1650°F for at least fifteen minutes. The specimens were then removed from the furnace. One was placed on a ceramic pad to air cooled, which is call normalizing. The other specimen was quickly place in a 10% brine solution, which is called quenching. The quenched specimen had to be placed in the brine as quickly as possible to prevent any cool down by the air. If it would have been cooled by air and not quenched first it would have affected our outcome. When the brine quenched specimen was cool enough to handle, we ground the cylindrical surface on the fine grinding table using 240 grit. Then, we dried the specimens off and measured their hardness. The air cooled specimen was soft enough to measure on the Rockwell B scale. The brine quenched specimen was hard enough to use the Rockwell C scale. Once we measured the cylindrical surface of both specimens and added the appropriate correction factors, we prepared them for the viewing under the microscope. We then mounted the specimens in Bakelite. We then coarse ground the specimens on a belt grinder using 120 grit sandpaper. Next, we fine ground the specimens on the water-flushed hand grinding table. We used 240, 320, 400, and 600 grit in the exact order. The specimens were rotated 90° each time they were moved to a pad with a finer grit. Next, we cleaned both specimens thoroughly and washed our hands. Then, we moved to the polishing wheel using a...