Tensile Test of Steel for Stress vs. Strain Diagram - MyWeb at WIT

MECH180 Strength of Materials Lab #5
Tensile Test of Steel for
Stress vs. Strain Diagram
OBJECTIVE:
To obtain the data necessary to draw a stress vs. strain diagram for a ¾ inch by 18 inch bar of
1020 HR steel, or other test specimen and to verify some important properties such as elastic limit,
maximum strength, percent elongation, percent reduction of area, and modulus of elasticity.
APPARATUS:
Hydraulic or other testing machine, extensometer, 12-inch scale, trammel punch, micrometer,
hammer and the test specimen
METHOD:
Measure the diameter of the bar at 2 locations and use the average in your calculations.
Punch the bar with the 8-inch trammels leaving 5 inches at each end to chuck.
Chuck the bar in the machine heads with proper shims to keep the wedges centered in
the head. Operate the machine according to instructions.
Engage the extensometer as instructed in the 8- inch punch marks. Apply a small load
(500#) to take up lost motion in extensometer. Zero the load.
Take extensometer readings at each 1,000-lbs. increment of load up to 14,000 lbs. at slow
speed, and then take frequent readings (200#) through 22,000 lbs. or through the yield
load being VERY careful not to bottom out the extensometer.
Stop the machine and remove the extensometer and proceed with the test to maximum,
then on to breaking the bar.
After removing the extensometer, measure the strain with dividers. Get the load at a
gauge of 8.1 inches and then for every 0.1 inches increase in gauge length.
Tabulate all data and results.
Change the procedure to fit your size of test bar. In all cases, first estimate the probable
yield and maximum loads, and from these loads decide upon the increments of loading
to use. Draw the Stress vs. Strain diagram. Show your computations.
CONCLUSIONS:
Compare your results with published values. Comment on the comparisons. Explain fully the
progress of the test with all visual observations noted.
Material Yield
(lbs.)
¾” Dia. Hot Roll Steel
1020
Max.
(lbs.)
Break
(lbs.)
Yield
(PSI)
Max
(PSI)
Stress-Strain Diagram.docx Page 1 of 3

MECH180 Strength of Materials Lab #5
DATA:
Material________ Initial diameter________ Initial Gage Length_________
Rdng Load Elongation Rdng Load Elongation Rdng Load Elongation
1 41 81
2 42 82
3 43 83
4 44 84
5 45 85
6 46 86
7 47 86
8 48 88
9 49 89
10 50 90
11 51 91
12 52 92
13 53 93
14 54 94
15 55 95
16 56 96
17 57 97
18 58 98
19 59 99
20 60 100
21 61 101
22 62 102
23 63 103
24 64 104
25 65 105
26 66 106
27 67 107
28 68 108
29 69 109
30 70 110
31 71 111
32 72 112
33 73 113
34 74 114
35 75 115
36 76 116
37 77 117
38 78 118
39 79 119
40 80 120
RESULTS:
Stress-Strain Diagram.docx Page 2 of 3

MECH180 Strength of Materials Lab #5
Proportional Limit__________ Modulus of Elasticity__________
Yield Stress__________ Modulus of Resilience__________
Ultimate Tensile Stress__________ Modulus of Toughness__________
Rdng Stress Strain Rdng Stress Strain Rdng Stress Strain
1 41 81
2 42 82
3 43 83
4 44 84
5 45 85
6 46 86
7 47 86
8 48 88
9 49 89
10 50 90
11 51 91
12 52 92
13 53 93
14 54 94
15 55 95
16 56 96
17 57 97
18 58 98
19 59 99
20 60 100
21 61 101
22 62 102
23 63 103
24 64 104
25 65 105
26 66 106
27 67 107
28 68 108
29 69 109
30 70 110
31 71 111
32 72 112
33 73 113
34 74 114
35 75 115
36 76 116
37 77 117
38 78 118
39 79 119
40 80 120
Stress-Strain Diagram.docx Page 3 of 3