This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Cast Irons”.
1. Presence of which material in a gray cast iron causes reduced ductility?
Explanation: Among all the types of cast irons that are manufactured, gray cast irons are most widely used. The colour of this alloy is dull gray. Gray cast iron contains graphite flakes, which are responsible for the reduced ductility and strength.
2. What would be the tensile strength of gray cast iron of class 20?
a) 120 MPa
b) 163 MPa
c) 138 MPa
d) 152 MPa
Explanation: Tensile strength of gray cast iron of class 20 is 163 MPa.
3. What is the tensile strength of thick gray cast iron?
a) 71 MPa
b) 83 MPa
c) 95 MPa
d) 107 MPa
Explanation: Tensile strength of thick gray cast iron is 83 MPa.
4. What is the tensile strength of thick gray cast iron?
a) 276 MPa
b) 283 MPa
c) 295 MPa
d) 207 MPa
Explanation: Tensile strength of thick gray cast iron is 276 MPa.
5. Up to what mass of gray cast irons can shell molds take?
a) 300 kg
b) 400 kg
c) 500 kg
d) 600 kg
Explanation: Shell molding is one of the most important processes which has also been employed for the production of gray cast irons. Gray cast irons weighing up to around 500 kg are usually processed by this method.
6. Green sand molding provides the best surface finish.
Explanation: Green sand moldings are found to provide good amount of surface finish, but an even better quality of surface finish and accuracy of dimensions is offered by shell molding process.
7. Shell molding process is a costly process for gray iron castings.
Explanation: When gray cast irons have to be processed, there is some amount of machining required to it, which demand high costs. But, if gray cast irons have to be shell molded, the overall cost of the product goes down, making it an economical process.
8. Up to what thickness can hot box process can be used for production?
a) 10 mm- 40 mm
b) 30 mm- 50 mm
c) 40 mm- 80 mm
d) 70 mm- 100 mm
Explanation: In hot box process, there is a core box employed, wherein the sand mixtures are poured along with the liquid resins, which act as binders. The thickness up to which hot box process can be used is 70 mm to 100 mm.
9. Which of the following materials cannot be used for making a core box?
d) Cast iron
10. What is the temperature in a core box typically?
a) 120°C – 160°C
b) 180°C – 260°C
c) 200°C – 270°C
d) 290°C – 350°C
Sanfoundry Global Education & Learning Series – Casting, Forming and Welding.
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