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221.

A steel piece after hardening is heated to 300?C and then cooled in oil. The property imparted to the steel piece will be

A.	Softness	B.	Toughness
C.	Hardness	D.	Annealing

222.

The minimum carbon percentage required in steel so that it may respond to hardening by heat treatment is

A.	0.02 percent	B.	0.08 percent
C.	0.2 percent	D.	0.8 percent

223.

The effect of austenitic grain size development during heat treatment is

A.	lower hardenability	B.	greater toughness
C.	lower internal stress	D.	All of the above

224.

During hardening soft spots can be avoided by

A.	using a more effective cooling medium	B.	protecting against decarburization in heating
C.	obtaining a more homogeneous structure employing annealing or normalising before hardening	D.	Any of the above

225.

Insufficient hardness after tempering may be due to

A.	tempering temperature too low	B.	tempering temperature too high
C.	oxidising atmosphere in the furnace	D.	Any of the above

226.

A steel specimen is heated to 730?C and cooled at the slowest possible rate in the furnace. Which property will be imparted to the steel piece?

A.	Hardness	B.	Softness
C.	Toughness	D.	Tempering

227.

Warping of articles during heat treatment may be due to

A.	non-uniform heating	B.	non-uniform cooling
C.	internal stresses in the article before heating

228.

If an article develops insufficient hardening after quenching it could be due to any of the following EXCEPT:

A.	Internal stresses in the article before heating	B.	Hardening temperature too low
C.	Cooling rate too slow	D.	Holding insufficient at the hardening temperature

229.

If an article develops insufficient hardening after quenching, the defect can be corrected by

A.	removing scale from surface	B.	normalising or annealing followed by hardening
C.	reheating the article in oxidizing atmosphere and quenching	D.	Any of the above

230.

During burning of grain boundaries

A.	regions enriched in carbon are formed in first state of burning	B.	non-oxidized cavities and blow holes are formed during second stage
C.	iron oxide inclusions are formed in third stage	D.	All of the above