MMET 207 LAB FINAL QUESTIONS AND ANSWERS
Tensile Testing Procedure - Answers :1) Secure a tensile test specimen from your
instructor
2) Stamp a set of indentation marks on the specimen using the gagelength, two-prong
indentor
3) Place the tensile specimen in the machine with the load gage set on the 60,000
pound scale. Make sure that the scale is zeroed
4) Load the machine until the dial reads 11,000 pounds. Measure the distance between
the indentation marks with the dividers and vernier calipers. Record load ad calculate
for stress and strain
5) Increase the load on the machine to 13,000 pounds. Measure the distance between
the indentation marks with the dividers and vernier calipers. Record load ad calculate
for stress and strain
6) Carefully observe the loading dial. Increase the loading until the sample necks.
Record load ad calculate for stress and strain
7) Increase loading until failure occurs. Be sure to read where the load is at all times so
that you can identify the breaking load. Record the load and calculate stress.
8) Lower the bottom jaw using the lower button, then unload the machine. Then the
specimen may be removed. Remove the broken tensile pieces from the machine and
carefully place the broken ends together. Measure and record the total length between
the indentations and calculate percent elongation
9) Measure the diameter at the break and calcuate the final area of metal at the break
When the behavior is elastic but not proportional - Answers :Proportional limit
When the material begins plastic deformation - Answers :Yield strength
The highest strength achievable - Answers :Tensile strength or ultimate tensile strength
Strength when material breaks - Answers :Breaking strength
Stretch, related to percent elongation - Answers :Ductility
Measure of stiffness of the material - Answers :Modulus of elasticity
What is hardness testing for? - Answers :To measure a metal's resistance to indentation
What are the three methods of indenting materials? - Answers :Rockwell, Brinell,
VIckers
Which of the three methods of hardness testing is widely used? - Answers :Rockwell
hardness testing
, What are the major loads for the Rockwell hardness testing? - Answers :a. Regular: 150
kg, 100 kg, and 60 kg
b. Superficial: 15 kg, 30 kg, and 45 kg
What are the minor loads for the Rockwell hardness testing? - Answers :a. 10 kg.
Regular
b. 3 kg. Superficial
Which indentors are used for each Regular depending on scale? - Answers :A and D
are Diamond for Regular
N is Diamon for Superficial and T is Steel Ball
What is the set up for A Regular scale on Rockwell Hardness Tesiting? - Answers :10
kg Minor Load
60 kg Major Load
Diamond Indentor
What is the set up for C Regular scale on Rockwell Hardness Tesiting? - Answers :10
kg Minor Load
150 kg Major Load
Diamond Indentor
What is the set up for N Superficial scale on Rockwell Hardness Tesiting? - Answers :3
kg Minor Load
Whatever number it specifies
Diamond Indentor
What is the set up for T Superficial scale on Rockwell Hardness Tesiting? - Answers :3
kg Minor Load
Whatever number it specifies
Steel Ball Indentor
Why is it possible to get hardness reading + or - 3 points aprt on the same metal with
the same scale? - Answers :The are where the indentation was made could have been
closed to previous indentations.
How far apart must two adjacent indentations be? Why? - Answers :3 times the
diameter
Because of residual stress
How far must an indentation be from the edge of the specimen? Why? - Answers :2 and
a halft times the diameter
It might read the hardness of the edge and mess the reading.
Tensile Testing Procedure - Answers :1) Secure a tensile test specimen from your
instructor
2) Stamp a set of indentation marks on the specimen using the gagelength, two-prong
indentor
3) Place the tensile specimen in the machine with the load gage set on the 60,000
pound scale. Make sure that the scale is zeroed
4) Load the machine until the dial reads 11,000 pounds. Measure the distance between
the indentation marks with the dividers and vernier calipers. Record load ad calculate
for stress and strain
5) Increase the load on the machine to 13,000 pounds. Measure the distance between
the indentation marks with the dividers and vernier calipers. Record load ad calculate
for stress and strain
6) Carefully observe the loading dial. Increase the loading until the sample necks.
Record load ad calculate for stress and strain
7) Increase loading until failure occurs. Be sure to read where the load is at all times so
that you can identify the breaking load. Record the load and calculate stress.
8) Lower the bottom jaw using the lower button, then unload the machine. Then the
specimen may be removed. Remove the broken tensile pieces from the machine and
carefully place the broken ends together. Measure and record the total length between
the indentations and calculate percent elongation
9) Measure the diameter at the break and calcuate the final area of metal at the break
When the behavior is elastic but not proportional - Answers :Proportional limit
When the material begins plastic deformation - Answers :Yield strength
The highest strength achievable - Answers :Tensile strength or ultimate tensile strength
Strength when material breaks - Answers :Breaking strength
Stretch, related to percent elongation - Answers :Ductility
Measure of stiffness of the material - Answers :Modulus of elasticity
What is hardness testing for? - Answers :To measure a metal's resistance to indentation
What are the three methods of indenting materials? - Answers :Rockwell, Brinell,
VIckers
Which of the three methods of hardness testing is widely used? - Answers :Rockwell
hardness testing
, What are the major loads for the Rockwell hardness testing? - Answers :a. Regular: 150
kg, 100 kg, and 60 kg
b. Superficial: 15 kg, 30 kg, and 45 kg
What are the minor loads for the Rockwell hardness testing? - Answers :a. 10 kg.
Regular
b. 3 kg. Superficial
Which indentors are used for each Regular depending on scale? - Answers :A and D
are Diamond for Regular
N is Diamon for Superficial and T is Steel Ball
What is the set up for A Regular scale on Rockwell Hardness Tesiting? - Answers :10
kg Minor Load
60 kg Major Load
Diamond Indentor
What is the set up for C Regular scale on Rockwell Hardness Tesiting? - Answers :10
kg Minor Load
150 kg Major Load
Diamond Indentor
What is the set up for N Superficial scale on Rockwell Hardness Tesiting? - Answers :3
kg Minor Load
Whatever number it specifies
Diamond Indentor
What is the set up for T Superficial scale on Rockwell Hardness Tesiting? - Answers :3
kg Minor Load
Whatever number it specifies
Steel Ball Indentor
Why is it possible to get hardness reading + or - 3 points aprt on the same metal with
the same scale? - Answers :The are where the indentation was made could have been
closed to previous indentations.
How far apart must two adjacent indentations be? Why? - Answers :3 times the
diameter
Because of residual stress
How far must an indentation be from the edge of the specimen? Why? - Answers :2 and
a halft times the diameter
It might read the hardness of the edge and mess the reading.
