The Different Proof Strength of Threaded Fasteners

The threaded fastener can be found in many force devices, instruments or large-scale equipment, the most common such like machine tools for manufacturing, automobiles or trains for transportation. With a threaded fastener, the clamping force holding the two pieces of material together is produced by a torque being applied to the fastener to stretch it and this is maintained during the service life of the fastener. Those fasteners include rivet bolts mated with hex rivet nuts and screws with threads in the material.

1. Low- or medium-carbon steel bolts usually have a minimum proof strength of about 225 to 400 Pa, the proof strength being the maximum stress the bolt can withstand without acquiring a permanent set.

2. The quenched and tempered medium carbon bolts have the minimum proof stress about 600 to 650 MPa.

3. Due to its hard and high density metal properties, for quenched and tempered alloy steel bolts, the minimum proof stress is approximately up to 970 MPa.

Apart from offering the strong clamping force, the thread on the bolts enables bolts removing from the steel rivet nuts, this production process makes fasteners widely used in many industries, threaded fasteners are particularly useful for joining components that are likely to need to be dismounted during the life of the product.