- Chemical Engineering Basics - Section 1
- Chemical Engineering Basics - Section 2
- Chemical Engineering Basics - Section 3
- Chemical Engineering Basics - Section 4
- Chemical Engineering Basics - Section 5
- Chemical Engineering Basics - Section 6
- Chemical Engineering Basics - Section 7
- Chemical Engineering Basics - Section 8
- Chemical Engineering Basics - Section 9
- Chemical Engineering Basics - Section 10
- Chemical Engineering Basics - Section 11
- Chemical Engineering Basics - Section 12
- Chemical Engineering Basics - Section 13
- Chemical Engineering Basics - Section 14
- Chemical Engineering Basics - Section 15
- Chemical Engineering Basics - Section 16
- Chemical Engineering Basics - Section 17
- Chemical Engineering Basics - Section 18
- Chemical Engineering Basics - Section 19
- Chemical Engineering Basics - Section 20
- Chemical Engineering Basics - Section 21
- Chemical Engineering Basics - Section 22
- Chemical Engineering Basics - Section 23
- Chemical Engineering Basics - Section 24
- Chemical Engineering Basics - Section 25
- Chemical Engineering Basics - Section 26
- Chemical Engineering Basics - Section 27
- Chemical Engineering Basics - Section 28


Chemical Engineering Basics - Engineering
Q1: Hardening of steel is not possible, unless it is heated __________ critical point.A above the highest
B above the lowest
C between the first & second
D between the second & third
ANS:B - above the lowest "Above the lowest critical point" refers to heating the steel above its lower critical temperature during the hardening process. This critical temperature is also known as the Ac1 temperature. When steel is heated above this critical temperature, its microstructure undergoes a transformation. Specifically, the steel transitions from a ferrite-pearlite or ferrite-cementite microstructure to austenite, which is a face-centered cubic (FCC) crystal structure. Austenite is a high-temperature phase of steel that has different properties compared to the lower-temperature phases. Heating the steel above the lower critical temperature allows the carbon atoms to dissolve into the austenite phase, which is essential for achieving hardness during the subsequent quenching process. After the steel has been heated to a temperature above the lower critical point and held there for sufficient time to ensure uniformity, it is then rapidly cooled (quenched) to room temperature to achieve the desired hardness. |


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