Quenched and tempered steels are very resistant steels characterized by a chemical composition that ensures the best performance after the quenching and subsequent tempering heat treatment. This process gives the pieces unique hardness and toughness, making them suitable for use even in very critical conditions.
Through the quenching and tempering process, it is possible to obtain from steel the right compromise between resilience and toughness. In the hardened status the steel shows high hardness with very low toughness properties; it is then necessary to resort to tempering in order to cancel all stresses and brittleness.
These types of steels are generally used for the construction of mechanical devices subjected to considerable static and dynamic loads and are widely used in the mechanical industry for shafts of any type, rods, connecting rods, levers, etc.
The wide variety of uses, sizes and shapes of mechanical devices to which the quenched and tempered steels are intended for, requires a scrupulous choice of steel according to the stresses which the part will be subjected to.
Types of quenched and tempered steels.
Quenched and tempered steels can be divided in two categories: alloyed and non-alloyed.
– Alloyed quenched and tempered steels: they contain alloying elements i.e., Chromium for hardness and toughness, Molybdenum to reduce brittleness upon tempering, Nickel for resilience and fatigue resistance.
They are suitable for high dynamic and static loads and are used in various fields among which the construction of vehicles i.e., in the clutch, in the axles and in the fasteners. While in the mechanical and plant engineering field they are used to build pinions, columns for presses, gear wheels as well as saw blades, chain links and shafts.
– Non-alloyed quenched and tempered steels: that is, without the addition of alloying elements. They differ from one another due to the greater or lower presence of carbon. They have a limited temperability and do not allow well-transformed structures to be obtained on pieces with elevated thickness.
