183. Which of the following element is added to steel to impart high strength and toughness
A.Magnesium
B.Manganese
C.Phosphorous
D.Sulphur

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184. Which of the following has better capability to bear sudden and excessive shocks
A.Cast iron
B.Pig iron
C.White iron
D.Wrought iron

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185. Among the following materials, the most suitable material for withstanding shock and vibration without danger of cracking is
A.Chilled cast iron
B.Gray cast iron
C.Malleable iron
D.White cast iron

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186. Hardenability of stell
A.Is the depth of penetration obtained by Vickers test
B.Is the ability of steel to resist abrasion, wear and penetration
C.Is the property which determines the depth of the hardened zone induced by quenching
D.Is achieved throughout its full depth, when the actual cooling rate equals the critical cooling rate

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187. Following elements have body-centered cubic structure
A.Gamma iron (9100 to 1400°C), Cu, Ag, Au, Al, Ni, Pb, Pt
B.Mg, Zn, Ti, Zr, Be, Cd
C.α iron (below 910°C and between 1400 to 1539°C), W, V. Mo, Cr, Na, K, Li etc
D.All of the above

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188. Silicon steel used for electrical equipment contains following percentage of silicon
A.0.2 to 0.5%
B.2%
C.3.4%
D.6.5%

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189. Following elements have hexagonal close-pack structure
A.Gamma iron (910° to 1400°C), Cu, Ag, Au, Al, Ni, P6, Pt
B.Mg, Zn, Ti, Zr, Be, Cd
C.α iron (below 910°C- and between 1400 to 1539°C), W, V, Mo, Cr, Na, K, Li etc
D.All of the above

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