Stress-Strain Curve for Ductile material :-
A stress-strain curve or diagram shows the relationship between stress and Strain by gradually applying load to measure the deformation or in other words.
To study the behaviour of material under tension a stress strain curve is made during the tensile test of a specimen.
In stress strain curve or diagram, the stress is taking along the vertical axis and Strain is taking along horizontal axis.
Stress-Strain Curve for ductile material (Mild Steel) :-
The stress starin diagram of ductile material say mild steel are shown below:-
Pointsis to be covered in stress strain curve:-
- Proportional Limit.
- Elastic Limit.
- Plastic Limit (upper yield point or lower yield point)
- Ultimate Stress.
- Breaking Stress.
- Proportional limit or limit of proportionality:- From O to A curve is straight line which means stress and Strain are proportional to point A. Point A upto which Hook's law holds good known as proportional limit or limit of proportionality which is defined as that stress at which stress strain curve begins to deviate from the straight line.
- Elastic limit:- When load is increased from point A to uoto point B, the material retains its elastic properties. The point B is known as elastic limit and can be defined as the stress developed in material without causing any plastic deformation. At this point elongation in mild steel is about 2% . For some materials the proportional limit and elastic limit may be the same.
- Plastic Limit:- When material is stressed beyond elastic limit, it deforms permanently are called plastic Limit or plasticity and does not recovered it's original shape and size on removal of load. From point B to C strain increases at faster rate than the stress. At point C material yields before the load and there is appreciable strain. Immediately after yielding ,there is a small load drop at point D. Thus for mild there is two yield point C and D known as Upper and lower yield point respectively. Stress at these points are correspondingly known as yield point stress.
- Ultimate Stress:- At point D , the specimen regains some strength and high value of stresses are required for higher strains. The stress goes on increasing till the point E is reached, where stress attains it's maximum value known as ultimate tensile stress of the material. It can be defined as the largest stress reached in a test for the original cross-sectional area of the specimen.
- Breaking Stress:- After the specimen has reached the ultimate Stress, a neck formed which decreases the cross-section area of the specimen. Stress required to break away the specimen is somewhat less than the maximum stress. Therefore, the stress is reduced until the specimen breaks away at point F. Stress at this point is known as breaking stress.
I hope you like my explanation of Stress Strain Curve of ductile material. If there is any mistakes or important the don't be hisitate just share your worthly comments.
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