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What is the difference between tensile strength and yield strength?

Two of the terms you encounter when considering fasteners are tensile strength and yield strength. Both reveal the strength of the fastener. But, despite the similarities of these terms, they are not interchangeable. We at Bossard want to explain the differences, so you can make an informed decision when choosing fasteners.

  • You don’t want a fastener that is too weak for your application.
  • But you also don’t want a fastener that is too strong because you’re spending extra money on strength that you don’t need.

Why is a fastener like a spring?

A fastener like a bolt behaves in the same way as a spring.

  • When you use a fastener to clamp down two components, they act as a compression spring.
  • Meanwhile, the bolt acts as a tension spring and stretches when you apply force to it.

If you do not overload the bolt, it springs back to its original length when you release the load. But, if you overload the bolt beyond its yield point, it does not return to its original shape and suffers permanent deformity.

Coming to terms

The point before which the fastener fractures indicates the tensile strength. You want to focus on this number when choosing fasteners that must sustain huge forces.

Yield strength generally comprises 80 or 90 percent of tensile strength. Yield indicates the point at which the fastener starts deforming. A useful way to determine the yield strength of a bolt based on its tensile strength is to examine its property class.

  • Property class of 10.9: The 9 after the decimal point shows that the yield strength comprises 90 percent of tensile strength.
  • Property class of 8.8: The 8 after the decimal points shows that yield strength comprises 80 percent of tensile strength.

Proof Load

A third term that’s often associated with fasteners is proof load. Proof load is the maximum load you can apply to a fastener before it permanently deforms. For Bossard fasteners, you can find the values for tensile strength, yield strength, and proof load in the technical section of our website.

For more information about tensile strength and yield strength, contact us at provenproductivity@bossard.com today.

What is the difference between tensile strength and yield strength? by
May 15, 2020

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