This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Annealing – 2”.
1. Process annealing is applied to which kind of materials?
a) Steel castings
b) Low carbon steels
c) High carbon steels
d) Medium carbon steels
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Explanation: Process annealing is a method used to soften and increase the ductility of a previously strain-hardened metal. It is mainly used in case of steel wires and sheet products, especially low carbon steels.
2. For process annealing, the steel is heated at a temperature range of _________
a) 550-650oC
b) 723-910oC
c) 723-1138oC
d) 750-800oC
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Explanation: In process annealing, the low carbon steels are heated to a temperature slightly below the A1 line, which ranges between 550oC and 650oC. Full annealing is carried out at 723-910oC (hypoeutectoid) or 723-1138oC (hypereutectoid).
3. Which among the following is not applicable to process annealing of steels?
a) Low scaling
b) Rapid
c) Expensive
d) Single phase morphology
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Explanation: Process annealed steels are heated around 550-650oC, held for some time for softening, then cooled at any desired rate. This process induces a single phase morphology. This process is cheaper, more rapid, and produces less scaling as the material is not heated at a high temperature like for full annealing.
4. What happens when internal residual stresses are not removed?
a) Coarse structure
b) Reduction of grain size
c) Distortion
d) Recrystallization
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Explanation: When internal residual stresses are not removed, distortion or warpage of the material may occur. In order to remove these stresses, stress relief annealing is carried out.
5. Subcritical annealing is another name for ____________
a) Process annealing
b) Stress relief annealing
c) Recrystallization annealing
d) Spheroidise annealing
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Explanation: Process annealed steels are heated around 550-650oC, held for some time for softening, then cooled at any desired rate. This process induces a single phase morphology. This process is otherwise known as subcritical annealing.
6. Commercial annealing is another name for ____________
a) Process annealing
b) Stress relief annealing
c) Recrystallization annealing
d) Spheroidise annealing
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Explanation: When internal residual stresses are not removed, distortion or warpage of the material may occur. Stress relief annealing is carried out to remove these stresses caused by castings, quenching, machining, welding etc. Stress relief annealing is otherwise also known as commercial annealing.
7. Removal of internal residual stresses at low temperatures is known as ________
a) Recrystallization
b) Recovery
c) Morphology
d) Phase transformation
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Explanation: Recovery is a low-temperature phenomenon used to remove internal residual stresses. This is done with little change in mechanical properties and no major changes in microstructure. Stress relief is also known as recovery.
8. What kind of annealing does this graph illustrate?
a) Process annealing
b) Stress relief annealing
c) Recrystallization annealing
d) Spheroidise annealing
View Answer
Explanation: Stress relief annealing is carried out to remove the stresses caused by castings, quenching, machining, welding etc. This can be done by prolonged heating of the material slightly above and below the A1 line. Full annealing occurs above the A1 and A3 lines, whereas process annealing occurs slightly below the A1 line.
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