Quiz: Mechanical Engineering 30 April 2020

Quiz: Mechanical Engineering
Exam: UPPSC AE
Topic: Production Engineering

Each question carries 3 mark.
Negative marking: 1 mark
Time: 10 Minute

Q1. Sub-zero treatment of steel
(a) is used to reduce the retained austenite in hardened steel
(b) increases the ability of steel to work in sub-zero atmosphere
(c) is used to suppress martensite transformation
(d) is performed after hardening operation to induce temper brittleness

Q2. Creep rate in ternary stage
(a) decreases
(b) remains constant
(c) increases
(d) none of these

Q3. Which of the following super alloys is age-hardenable?
(a) Incoloy
(b) Nimonic
(c) Stellite
(d) Inconel

Q4. Why does crater wear start at some distance from the tool-tip?
(a) Tool strength is minimum at that region
(b) Cutting fluid cannot penetrate that region
(c) Tool temperature is maximum in that region
(d) Stress on rake face is maximum at that region

Q5. Warm metal working is applied extensively for
(a) Rolling
(b) Extrusion
(c) Forging
(d) Drawing

Q6. The mode of deformation of metal during spinning is
(a) bending
(b) stretching
(c) rolling and stretching
(d) bending and stretching

Q7. Ironing is used to
(a) increase wall thickness of the drawn cup
(b) obtain uniform wall thickness in the drawn cup
(c) decrease wall thickness of the drawn cup
(d) decrease the diameter of rod

Q8. What does hydro-static pressure in hydro-static extrusion improve?
(a) Ductility
(b) Compressive strength
(c) Brittleness
(d) Tensile strength

Q9. Spring back factor of the metal depends upon
(a) both bend radius and thickness
(b) bend radius only
(c) thickness only
(d) surface area

Q10. Which of the following is used in manufacturing of extrusion nozzles?
(a) Grey cast iron
(b) Malleable cast iron
(c) White cast iron
(d) Nodular cast iron

Solutions

S1. Ans.(a)
Sol. At sub-zero temperature retained austenite is converted into martensite completely.

S2. Ans.(c)
Sol. In primary stage, creep rate decreases; in secondary stage, the creep rate remains constant and in ternary stage the creep rate increases due to necking.

S3. Ans.(b)
Sol. Nimonic alloy is an age-hardenable alloy.

S4. Ans.(c)
Sol. Crater wear occurs at some distance from tool-tip because temperature is the highest at some distance from tool-tip in tool-chip interface region.

S5. Ans.(c)
Sol. Warm working is the plastic deformation of metal below the re-crystallization temperature range and above room temperature. It is used extensively for forging to achieve advantages of hot and cold working.

S6. Ans.(d)
Sol. Spinning is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part. Spinning is the combination of bending and stretching operations.

S7. Ans.(b)
Sol. Ironing is a very important process when employed in combination with deep drawing to produce a uniform wall thickness and to increase the wall height.

S8. Ans.(a)
Sol. Hydro-static friction helps to eliminate the friction between the work surface and die. It also increases the ductility of the metal to be extruded and enable a brittle material for extrusion process.

S9. Ans.(a)
Sol. Spring back is the elastic recovery after elastic-plastic deformation of metal part, both thickness and bend radius affect the spring back characteristics.

S10. Ans.(c)
Sol. Extrusion nozzle is made of hard materials so that, extrusion of hard materials will not wear out nozzle.

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