Question 1
High temperature tempering develops a ________ structure.
A. Non-lamellar
B. Sorbite
C. Tempered-troostite
D. Pearlite
View Answer
Answer: Option B
Explanation:
High-temperature tempering is usually carried out in a temperature range between 500oC and 650oC. This process develops a sorbite structure. This is used to completely eliminate internal stresses in the material.
Question 2
How is the ductility of the material affected due to tempering?
A. Increases with an increase in temperature
B. Decreases with an increase in temperature
C. Increases constantly
D. Does not change
View Answer
Answer: Option A
Explanation:
The hardness and tensile and yield strengths of the material decrease with increasing tempering temperature. On the other hand, however, it is noted that the ductility of the material increases with an increase in tempering temperature.
Question 3
How is the tensile strength of the material affected due to tempering?
A. Increases with an increase in temperature
B. Decreases with an increase in temperature
C. Increases constantly
D. Does not change
View Answer
Answer: Option B
Explanation:
We know that hardness of the material decreases with an increase in tempering time. Similarly, the tensile and yield strengths of the material also decrease with increase in tempering temperature.
Question 4
Internal stresses in martensite steel are relieved by heating at __________
A. 200oC
B. 500oC
C. 800oC
D. 1000oC
View Answer
Answer: Option A
Explanation:
Tempering usually involves heating the martensite steel below the eutectoid transformation temperature (250-650oC). When this martensite steel is heated at temperatures as low as 200oC, internal stresses are relieved.
Question 5
Low temperature tempering occurs at __________
A. 50-150oC
B. 150-250oC
C. 350-450oC
D. 500-650oC
View Answer
Answer: Option B
Explanation:
Tempering temperature is classified into three classes. Low temperature tempering occurs at 150-250oC. Medium and high temperature tempering occur at 350-450oC and 500-650oC correspondingly.
Question 6
Medium temperature tempering develops a ________ structure.
A. Non-lamellar
B. Sorbite
C. Tempered-troostite
D. Bainite
View Answer
Answer: Option C
Explanation:
Medium temperature tempering is usually carried out in a temperature range between 350oC and 450oC. This process develops a tempered-troostite structure.
Question 7
Temper embrittlement occurs at a temperature __________
A. Below 0oC
B. Above 250oC
C. Above 575oC
D. Above 1000oC
View Answer
Answer: Option C
Explanation:
Tempering of some steels and alloys may result in the reduction of toughness. This phenomenon is known as temper embrittlement. Temper embrittlement occurs when the steel is tempered above 575oC which is followed by slow cooling to room temperature.
Question 8
Tempering of martensite steel is done _________
A. Below eutectic temperature
B. Below eutectoid transformation temperature
C. At room temperature
D. At 1000oC
View Answer
Answer: Option B
Explanation:
Tempering is a process of heating martensite steel below the eutectoid transformation temperature (250-650oC). It is held there for some time and slowly cooled to room temperature.
Question 9
Tempering that results in a reduction of toughness is known as __________
A. Caustic embrittlement
B. Temper embrittlement
C. End-temper
D. Quench-temper embrittlement
View Answer
Answer: Option B
Explanation:
Tempering of some steels and alloys may result in the reduction of toughness. This phenomenon is known as temper embrittlement.
Question 10
What are the applications of medium temperature tempering?
A. Spring and die steels
B. Structural steels
C. Low alloy steels
D. Surface hardened regions
View Answer
Answer: Option A
Explanation:
Medium temperature tempering is applied on materials like spring steels and die steels. Likewise, high-temperature tempering is used on structural steels. Low-temperature tempering is applied to cutting and measuring tools of carbon and low alloy steels, as well as for surface-hardened and case-carburized parts.
Question 11
Which of the following is not a result of tempering?
A. Increased ductility
B. Improved toughness
C. Increased electrical conductivity
D. Internal stresses are relieved
View Answer
Answer: Option C
Explanation:
Martensite formed during the hardening process is too brittle and lacks toughness and ductility. This makes it unusable for many applications. Therefore, a heat treatment process called tempering is done to bring about these changes.
Question 12
Which tempering process is used to increase the endurance and elastic limit of the material?
A. Low-temperature tempering
B. Medium temperature tempering
C. High-temperature tempering
D. Endurance limit cannot be increased
View Answer
Answer: Option B
Explanation:
Medium temperature tempering is performed between 350oC and 450oC. This process develops a tempered-troostite structure and increases the endurance and elastic limits of the material.