Tempering of steel

Question 1

What is tempering?

Answer 1

reheating of steel below eutectoid temp, holding it and cooling to room temp

Question 2

What effects does tempering have?

Answer 2

> increases toughness and ductility
decreases hardness and strength
increases dimensional stability
minimizes residual stresses

Question 3

What effects does increasing tempering temp have?

Answer 3

higher toughness and ductility, lower hardness, lower yield stress and tensile strength

Question 4

Tempered steel has ____ ___ of work hardening, quenched steel has ___ ___ of work hardening

Answer 4

low rate; high rate

Question 5

Tempering range 150-200C

Answer 5

> gives modest increase in toughness without big loss in hardness
useful for high strength and fatigue resistance for primarily compressive load

Question 6

Tempering > 425C

Answer 6

significantly increases toughness, but hardness and strength decrease a lot

Question 7

Temper embrittlement (260-370C )

Answer 7

decreases toughness, but DOESN’T decrease ductility

> standard tensile test not useful for detecting temper embrittlement