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.Management Sciences
Category: Metallurgy
Tempering of steel cause________________?
A. Increases its toughness
B. Increases hardness
C. Increase ductility
D. decreases its toughness
18-B Stainless steel orthodontic wire has_______________?
A. 18% Nickel 8% Chrominum
B. 18% Chromium 8% Nickel
C. 18% Chromium 8% Cobalt
D. 18% Carbon 8% Iron
Asbestos liner is used in a casting ring to________________?
A. Facilitate venting of the mold
B. Retard the heating of the investment
C. Permit expansion of the world
D. All of the above
Heat hardening is the process done at_______________?
A. Heating 750°C and slowly cooling to zero degree
B. Heating quickly upto 450°C followed by sudden quenching
C. Heating upto 250°C for 15 to 30 min
D. Heating at 750°C and then quenching to room temperature
Binder used in Gypsum investment is_________________?
A. Silica
B. Quartz
C. Cristobolite
D. Calcium sulphate monohydrate
Titanium casting is done_____________?
A. Under vacuum in argon atmosphere
B. Under air pressure in nitrogen atmosphere
C. In specially fabricated aluminium vanadium
D. Using CAD-CAM technique
The yield strength of AUstenite (NiTi alloy) is______________?
A. 100 Mpa
B. 240 Mpa
C. 560 Mpa
D. 700 Mpa
Annealing is also known as_______________?
A. Soft hardening treatment
B. Hard hardening treatment
C. Precipitating heat treatment
D. Stress relieving heat treatment
Which of the following decrease with strain hardening______________?
A. Surface hardness
B. Strength
C. Proportion limit
D. Corrosion resistance
Fins and spines on the casting is seen due to_______________?
A. Prolonged heating:
B. Rapid heating me
C. Water film contamination
D. Too high pressure during casting
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