Question Set 8

Question No. 1

What is the composition of Cast iron Grade 35?


Carbon=2.90 – 3.10%, Manganese=0.60 – 1.00%, Silicon=1.50 – 1.90%, Sulphur=0.10%, Phosphorus=0.15%, Chromium=0.30%, Molybdenum=0.30%, Cupper=0.25%

Question No. 2                   

What are the super alloys?


Super alloys are an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, having good surface finish.

Question No. 3

Why the Super alloys used for land based turbines?


Super alloys are the top most alloys used for their excellent strength and corrosion resistance as well as oxidation resistance. No other alloys can compete with these grades.

Question No. 4

What kinds of NDT methods are available?


1.     Visual Inspection

2.     Microscopy inspection

3.     Radiography Test

4.     Dye Penetrate technique

5.     Ultrasonic testing

6.     Magnetic Particle inspection

7.     Eddy Current technology

8.     Acoustic Emission

9.     Thermograph

10.  Replica Metallographic

Question No. 5

What is Stress Corrosion cracking?


Stress corrosion cracking (SCC) is a process involving the initiation of cracks and their propagation, possibly up to complete failure of a component, due to the combined action of tensile mechanical loading and a corrosive medium.

Question No. 6

What is meant by D2 Material used for Die tooling?


D2 – High Carbon Cold Work Tool Steel.

D2 is a high Carbon, high Chromium, Molybdenum, Vanadium, Air hardening alloy tool steel which offers good wear resistance, high surface hardness, through hardening properties, dimensional stability and high resistance to tempering effect. D2 tool steel is also suitable for vacuum hardening.

Typical Composition:

C. = 1.50%, Si. = 0.30%Cr. = 12.00%Mo. = 0.80%V. = 0.90%

Question No. 7

What is Vacuum Induction Melting?


As the name suggests, the process involves melting of a metal under vacuum conditions. Electromagnetic induction is used as the energy source for melting the metal. Induction melting works by inducing electrical eddy currents in the metal. The source is the induction coil which carries an alternating current. The eddy currents heat and eventually melt the charge.

Question No. 8

What is the difference between Bolt and Screw?


The main difference was based on the load acting on it, and the size. For smaller loads, screws are enough but in case of greater-loads, bolts are to be used. In bolt we give centrifugal force or tangential force and screw we give axial force for driving.

Question No. 9

What is the function of a thrust bearing?


Thrust bearings keep the rotor in its correct axial position.

Question No. 10

What is the significance of Torque (in N-m) given in the engine specification?


It give the moment about any point or simple rotation.

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