Mechanical Engineering Objective Questions { Material science }

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330. Which of the following is not the objective of nitriding

A. Increase surface hardness

B. Increase fatigue limit

C. Increase wear resistance

D. Refine grain size

331. In normalising process, the hypoeutectoid steel is

A. Heated above A3 line and cooled very slowly in furnace so as to refine old structure

B. Heated below A1 line with a view to make steel ductile for cold working

C. Heated below A1 line and cooled slowly with a view to remove internal stresses

D. Heated above A3 line and cooled in air resulting in slight hardening

332. A big advantage of surface hardening by nitriding process is that

A. It is a mass production process

B. It is simple and cheap

C. Parts need not be quenched

D. It does not require furnace

333. Martensite is the supersaturated solution of carbon in

334. Martensite is the structure obtained by

A. Quenching austenite

B. Quenching austenite and then heating in the range of 200° to 375°C

C. Quenching austenite and then heating in the range of 375° to 660°C

D. Quenching austenite and then heating in the range of 600° to 700°C

335. The rollers of a cycle chain are subjected to following type of stress

336. Magnet steel contains high percentage of

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