Yield Strength vs Tensile Strength: Difference and Comparison

In physics, it is common to find the two worlds’ yield strength and tensile strength together. Both being the measure of the strength of a material, these two terms have some differences.

The difference lies in the fact that yield strength is the minimum force put on the material to cause it to change shape. But the tensile strength is the maximum force it bears before totally shattering. 

Key Takeaways

1. Yield strength measures the stress at which a material deforms permanently, while tensile strength quantifies the maximum stress a material can withstand before breaking.
2. Engineers use yield strength to determine a material’s safe working load, whereas tensile strength helps them understand its ultimate breaking point.
3. Materials with high yield strength can withstand significant deformation without losing their original shape, while those with high tensile strength resist breakage under tension.

Yield Strength vs Tensile Strength

The difference between yield strength and tensile strength is that yield strength is the smallest amount of force that can start the beginning of the deformation of an object. However, tensile strength is just the opposite of that, being the maximum force to cause breakage in an object. 

Yield strength has practical use while designing, which is a measure of strength. Yield strength is the minimum stress which is applied to an object before it changes its shape in such a way that you can not reverse it.

Another term associated with it is stress, which means intermolecular force. With increasing stress on a material, it slowly changes its shape in such a way that it’s irreversible. 

In general terms, it means the maximum stress that is given to material before it breaks down. When material stress increases, the intermolecular forces between the material will be lower than the external forces that deform the material.

Due to the stress of deformation being higher, the material is incapable of resisting and breaking. 

Comparison Table

Parameters of Comparison	Yield Strength	Tensile Strength
Condition of material	This tells  the irreversible deformation of the material	This tells about the breakage of the material
Stress	It is the minimum stress that causes deformation	It is the maximum strength to cause total breakage
Position in graph	It comes before the point of ultimate strength	It comes after the point of ultimate strength
Intermolecular forces	The intermolecular forces are just higher than the outside deformation forces	The intermolecular forces break from each other, thereby breaking the material.
Numerical value	The numerical value of yield strength is less than tensile strength.	The numerical value of tensile strength is more than yield strength.

What is Yield Strength?

Yield strength can be said to be the measure of the strength of an object. Stress means the amount or magnitude of the force you need to apply to something to cause deformation.

That is directly linked to yield strength. It is the least (minimum) amount of stress you put upon a material to cause it to deform beyond repair. The deformation has to be irreversible. 

The basic difference that the yield strength has from the tensile strength. In the case of yield strength, the stress that’s applied is minimum. Yield strength also has another in physics that is Elastic Limit.

Elastic limit or yield strength is that point of the stress strength graph beyond which, if stress is continued to be applied, the object will be irreversibly deformed beyond repair. 

Before reaching the yield strength, any damage or deformation reached can be reversed, and they are called elastic deformation. After the point of elastic limit is reached, it damages beyond repair and is called plastic deformation.

Its SI unit is Newton per (meter) ² which is also called Pascal. Yield strength is used in several areas of engineering to know the maximum load that can be applied to the part of a machine before it starts to get deformed.  

What is Tensile Strength?

Tensile strength has its practical applications in the field of engineering. The tensile strength is the maximum amount of stress that an object can bear before it gets broken.

Tensile strength is an intensive property. An intensive property does not depend upon the size of the object used. The limit of tensile strength comes after the elastic limit or yield after it attains the material breaks. 

The difference between yield strength and tensile strength depends on a few parameters. Yield strength is the minimum amount of stress applied to an object to cause a deformation beyond repair.

On the other hand, tensile strength is the amount of stress that the object can bear or withstand before it starts to break.

In this case, the externally applied force on the object is much greater than the intermolecular forces of attraction that bind the object together.

There are three types of tensile strength which are yield strength, ultimate strength, and at last, breaking strength. 

Many tests are there for measuring the tensile strength of an object. This test has applications in the construction industry, vehicle designing, rocket designing, safety and fitness industry, packing, textile industry, etc.

As it measures the strength, its unit is also Newton per (meter) ² or Pascal. We can find it by dividing force with the area concerned ( F/A)

Main Differences Between Yield Strength and Tensile Strength

1. Yield strength talks about the irreversible deformation taking place in a material. Whereas tensile strength talks about the breakage of the material
2. In the case of yield strength, it is the minimum amount of stress that the object can handle before it starts to get deformed. In contrast, tensile strength is the maximum amount of stress that can be applied before the material starts to fall apart. 
3. Yield strength comes before the tensile strength in the graph. In contrast, tensile strength comes before yield strength in the graphs. 
4. In yield strength, the intermolecular force still exists but is weaker than the breakage point. In tensile strength, intermolecular forces break. 
5. Yield strength has a higher numerical value than tensile strength, whereas tensile strength has a higher numerical value. 

References

1. https://link.springer.com/article/10.1007/s11665-008-9225-5
2. https://www.sciencedirect.com/science/article/pii/S0921509317309188