Question

what is the resultant phase or phases present in this eutectoid steel after the following heat treatment cycle: first quenched to m s>t>m f at a cooling rate faster than the critical cooling rate and held for t>10 4 sec, followed by reheating to t>727 o c and held for a long time, and then quenched to 700 o c and held there for t>10 4 seconds and then quench to t

Answer 1

The resultant phases in the eutectoid steel after the heat treatment cycle are martensite, austenite, and bainite.

Step-by-step explanation:

In the given heat treatment cycle, the eutectoid steel undergoes several phase transformations. Firstly, it is quenched to a temperature higher than the martensite start temperature (Ms) but lower than the martensite finish temperature (Mf). This results in the formation of martensite phase. The steel is then held at this temperature for a long time, allowing for complete transformation. Later, it is reheated to a temperature above the austenite transformation temperature (727 °C) and held for a long time. This leads to the formation of fully austenitic phase. Finally, it is quenched to 700 °C and held there, resulting in the formation of bainite phase.