2. Threaded thread properties

2.1 Metallurgical properties

Threads obtained by a cutting tapping operation do not have very notable metallurgical characteristics. In cutting tapping, the material undergoes a cutting operation in the same way as in other machining operations. The material is affected, if at all, only superficially, and is less likely to be affected if tapping is carried out at relatively low cutting speeds. Thermal stress is generally low, and there is no evidence of any metallurgical transformation of the thread material. Moreover, if temperatures in excess of 500 ˚C were produced, there would also be annealing of the tap's upper high-speed steel. It would then lose its hardness so would not be suitable for this application. On the other hand, mechanical stresses still exist and are often linked...