Deck 23: Heat Treatment of Metals

Question 1

Which of the following are the usual objectives of heat treatment (three best answers):

A)increase hardness
B)increase melting temperature
C)increase recrystallization temperature
D)reduce brittleness
E)reduce density
F)relieve stresses

Answer 1

increase hardness
reduce brittleness
relieve stresses

Question 2

Annealing consists of heating a metal to a suitable temperature, holding at that temperature for a certain time, and then slowly cooling:

Answer 2

True

Question 3

Which of the following are typical reasons to anneal a metal (three correct answers):

A)to heat the metal for hot working
B)to increase strength and hardness
C)to recrystallize strain-hardened metals
D)to reduce brittleness
E)to reduce ductility
F)to relieve stresses

Answer 3

to recrystallize strain-hardened metals
to reduce brittleness
to relieve stresses

Question 4

When annealing is performed to allow for further cold working of the part, it is called which one of the following:

A)full anneal
B)normalizing
C)process anneal
D)recovery anneal

Question 5

The hardness of steel increases with increasing carbon content, but the increase is achieved only through heat treatment:

Question 6

The time-temperature-transformation curve (TTT curve) for steel can best be described by which one of the following:

A)indicates how annealing is used to achieve a given desired microstructure
B)indicates how cooling rate affects the transformation of austenite into various possible phases
C)indicates how martensite is gradually transformed into tempered martensite as a function of time
D)indicates how various phases are obtained during heating as a function of time and temperature

Question 7

Martensite can best be defined as which one of the following:

A)a mixture of ferrite and carbide phases obtained by rapid cooling of austenite
B)a mixture of ferrite and carbide phases obtained by slow cooling of austenite
C)a phase consisting of an iron-carbon solution whose composition is the same as the austenite from which it was derived
D)a solution of cementite in ferrite obtained by rapid cooling of austenite

Question 8

Of the following quenching media, which one produces the most rapid cooling rate:

A)air
B)brine
C)oil
D)pure water

Question 9

The treatment in which the brittleness of martensite is reduced is called which one of the following:

A)aging
B)annealing
C)austenitizing
D)normalizing
E)quenching
F)tempering

Question 10

Tempering is a heat treatment applied to hardened steels that is best defined as which of the following (one correct answer):

A)heating and soaking at a temperature above the austenitizing level followed by rapid cooling
B)heating and soaking at a temperature above the austenitizing level followed by slow cooling
C)heating and soaking at a temperature below the austenitizing level followed by rapid cooling
D)heating and soaking at a temperature below the austenitizing level followed by slow cooling

Question 11

Hardenability refers to the relative capacity of a steel to be hardened by transformation to martensite:

Question 12

The most common method for measuring hardenability is which one of the following:

A)Brinell hardness test
B)Jominy end-quench test
C)Rockwell hardness test
D)tensile test

Question 13

In precipitation hardening, the hardening and strengthening of the metal occurs in which one of the following steps:

A)aging
B)quenching
C)solution treatment

Question 14

Which one of the following surface-hardening treatments is the most common:

A)boronizing
B)carbonitriding
C)carburizing
D)chromizing
E)nitriding