STRUCTURAL AND CONSTRUCTIONAL STEELS
Structural and constructional steels are unalloyed steels and they are normally marketed in their natural state, i.e. without any heat treatment.
The following special conditions may be agreed upon in the order:
- stress relieving (300 °C)
- soft annealing
- annealing to achieve certain structures
- annealing for mechanical working with a guaranteed hardness
- quenching and tempering
The rolled products are generally supplied without elimination of the calamine (oxide coating) but, if requested, they can be sand-blasted, pickled, peeled etc.
This steel family essentially contains low carbon and manganese, and limited amounts os sulphur and phosphorous. Sulphur is also added when they are used for tool working (SAE 1141 – 1116 – 1117).
In general, unless otherwise agreed in the order, mechanical properties such as failure, yield, elongation and resilience are not requested, but merely a maximum hardness value. They are considered as poor materials, but careful production makes them suitable for several delicate applications. Their ability to satisfy the cold-heading market is guaranteed by the long period of experimentation and their widespread use.
The most common structural and constructional steels are::