Rolled and cut threads

How can I tell the difference between rolled and cut threads?

How can I tell the difference between rolled and cut threads?This question can be answered using the Dutch standard NEN 6770, which defines the basic criteria and regulations for steel structures.

For bolts with a rolled thread, a reduction factor must be taken into account when determining the limiting strength. Although 100% certainty can often only be obtained through microscopic measurements, there are a few rules of thumb:

Rolled thread
Where the shank and thread meet, there is usually a small reduction; the end of the shank is generally concave (slightly hollow).

Cut thread
Where the shank and thread meet, there is no reduction; the end of the shank is generally completely straight.It holds true that, for equal dimensions and material quality, a cut thread and a rolled thread in static applications can both cope with the same loads. Only with dynamic loads is there an increased risk of fatigue cracking in a cut thread.