Characteristics of the materials
Carbon steel F-1140 in accordance with UNE-36011 (similar to AISI 1040 or 1045 and to steel CK-40 in accordance with DIN norms.
Normally, tubes made in threes with longitudinal welding are used. They are easy to weld tubes which fulfil the specifications described in the Spanish regulation MV-108-1976.
The qualities usually used are A-37 and A-42 and to a lesser extent, A-52, in accordance with UNE - 36080. These are approximately equivalent, in terms of other regulations, to the qualities ST 3373-2. RST 42.2 AND ST 52-3, in accordance with DIN 17100.
Normally, these are obtained by forging weldable steel F-1120, in accordance with UNE 36011 (Approximate equivalences: AISI 1035 or CK s/DIN)
Occasionally, they can be obtained by bar mechanization, using the same material. In any case, the welding drill and the bevel are mechanized to achieve the precise dimensional tolerance points.
These are obtained from steel F-1250, in accordance with UNE 36012 (equivalent to 34 Cr Mo 4 in accordance with DIN 17200, or to AISI 4340). In order to guarantee greater endurance of the material, and without affecting its capacity, tempering toughens the screws.