​​​​Callum O'Dwyer

Heat Treatment

• 1050C was chosen as the temperature to take the specimens into the austenitic range, as it is within the furnace's operating temperature and well clear of the duplex zone.

• For the low carbon steel, the duplex range temperature was selected as 800C, and 760C for the 0.5%C steel. In the adjacent graph, it can be seen that this is the midway point between austenisation and the eutectoid temperature for each steel. This will create some areas of austenisation, but the steel will not be fully transformed.

• Furnace was operated with the use of thick thermal gloves, eye protection and full PPE, and 12" long tongs to place the specimens into the furnace.

 

Cooling

• The slow cooled specimens were left in the furnace to cool overnight after the heat treatment. As the furnace is built to retain heat so well, there was a very slow cooling rate of 40K/hour on average. This is approximate to equilibrium conditions, or would fall on the far right of TTT plots and CCT diagrams.

• The quenched specimens were dropped into a bucket of iced brine. The brine has an improved heat transfer rate over plain water. The specimens were left until they were sufficiently cool to be removed from the buckets.