FREE-CUTTING STEELS
Free-cutting steels – which are commonly used in many mass production fields such as the automobile industry and household appliances – contain sulfur and some other elements, including tellurium, bismuth and lead, which promote machinability.
In particular, the sulfur ensures the fragmentation of the chip, lead reduces the friction between the tool and piece, extending the life of the tools, and the tellurium and bismuth further accentuate these characteristics.
Free-cutting steels are usually supplied in bars or rolls without heat treatment; some of these can however be tempered, normalized or annealed before finishing.
Thanks to the high surface hardness that can be obtained with the carburizing treatment, these steels are used to create those mechanical bodies for which a considerable surface hardness is necessary, such as gears, pins, bushes, shafts, and everything necessary for the transmission of motion.
The versatility of the range of carburized steels allows a vast range of uses to be covered, from the smallest gears to motor shafts of considerable size.
Temperability is the capacity of a steel subjected to rapid cooling (usually in oil or water) to more or less completely transform its structure, even on larger pieces.
The quenching and tempering treatment is generally carried out on pieces during the final stage of finishing, after most of the mechanical processing. In this case the semi-finished raw material can be provided in its natural rolling state or annealed for workability, depending on the type of steel.
Thanks to the technologies available, which are in accordance with the most advanced state-of-the-art, Rodacciai can also offer these products in the quenched and tempered state: the treatment is carried out on the rolled semi-finished product before drawing or peeling, so that the delivered product has in any case the appearance and typical surface characteristics of the cold-finished product.
The complete range of quenched and tempered steels, diversified in terms of chemical composition and therefore temperability, allows both the metallurgic and mechanical needs of all customers to be satisfied.
SURFACE HARDENED STEELS
Steels for surface hardening by induction
The series of carbon steels for surface tempering includes four types of materials with an increasing carbon content. The hardness that can be obtained on a surface hardened with this treatment is directly proportional to the steel’s carbon content.
All of these steels have a balanced chemical composition that allows a good machinability (S = 0.020 – 0.040) and an excellent repeatability of the heat treatment thanks to the constant size of the austenitic grain (Al = 0.020 – 0.050).
The required hardness values can only be obtained with certainty after the removal of the bar’s surface layer to eliminate any decarburization.
SPECIAL STEELS
Steels with different end uses
Rodacciai’s production range is completed by different types of special steels intended for multiple uses, which can satisfy the particular and niche needs of many users.
The steels reported in this section are those most commonly produced by Rodacciai, but several other types, not included in this site, are produced upon request.
STAINLESS STEELS
Steels resistant to corrosion in aggressive environments
The special characteristic of stainless steels is that they have a resistance to corrosion that is significantly higher with respect to other steels; some of them also have an excellent resistance to high temperatures.
These characteristics of stainless steels are obtained thanks to the addition of chromium and other alloy elements, and allow use even in particularly aggressive environments such as chemical plants, marine environments and offshore platforms. These qualities of resistance to assaults makes them perfect materials to be used also in architecture to increase the durability of the objects created.
Some of these steels, thanks to a chemical composition that is particularly rich in nickel and chromium, are called “refractory steels” and can withstand high temperatures with a limited loss of the mechanical characteristics.
Stainless steels can be provided in their natural rolling state or annealed, normalized, quenched and tempered, or heat-treated. Bars, coils, and wires are available with a wide variety of packaging.
| Execution | Profile | Range (mm) | Finish | Tolerances | |
| Bars | Rolled | Round | 20÷100 | Raw, peeled iron product | - |
| Drawn | Round hexagonal square special |
2÷40 4÷65 4÷55 |
Polished | ISA h9-h10-h11 | |
| Peeled - rolled | Round | 20÷80 | Polished | ISA h9-h10-h11 | |
| Ground | Round | 3÷80 | Polished | ISA h7-h8-h9-h10-h11 | |
| Coils | Drawn | Round hexagonal square special |
1÷22 3÷12 4÷12 |
Polished Stearate Phosphated |
ISA h9-h10-h11 |