A eutectoid steel undergoes the following heat treatments Us

A eutectoid steel undergoes the following heat treatments. Using the provided TTT diagram, determine the final microstructural composition. a) Starting at 800 degreeC, i) quench to 385 degreeC, hold for 1 minute, ii) quench to room temperature, iii) heat to 400 degreeC for 1 hour, then cool to room temperature. b) Starting at 825 degreeC, i) quench to 640 degreeC hold for 1 second, ii) quench 375 degreeC, hold for 100 seconds iii) then quench to room temperature.

Solution

A. Strating from 800, we have Austenite.

quenching it to 385, and holding it for 1 min gives us intermediate stage (50%)

Quenching to room temperature will result in Martensite.

Heating to 400 for 1 hour results in Fine Pearlite

And on cooling will still gives Fine Pearlite...........ANSWER

B. Quenching to 640 from 825 for 1 sec will touch the nose of TTT diagram.

Cooling to 375 for 100 seconds results in intermediate stage (50%)

now cooling it to room temperature will result in Banite and Martensite............ANSWER