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Concrinox TM
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Using stainless steel in concrete reiforcement structures
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TOUGHNESS
This is the resistance of a material to brittle fracture:it is determined by a Charpy test that measures impact properties.
Austenitic stainless steels (with a typical fcc structure, stable at all temperatures.) differ from carbon steels by their high toughness level (In some cases a double level can be achieved); austenitic-ferritic steels with a mixed structure of homogeneous austenite and ferrite grains and with a ratio between the two structures close to 1, present intermediate toughness values ranging between those of full austenitic steels and those of common C steels.
Two interesting factors are to be highlighted:
- Stainless steels toughness does not vary much when the work hardening level varies. That is particularly interesting since possible different production techniques (cold drawn or hot rolling) do not create great differences in resistance to fatigue cycles, and are able to generate notche effects at the base of the ribs ( if the radius is minimum) (See Fatigue resistance);
- Stainless steels toughness is not so much influenced by temperature since it does not present a transient ductile-fragile speed at around 0-20°C as happens in Carbon steels. That means that the mechanical behaviour of a stainless steel (in particular of an austenitic structure) does not change even at low temperatures (generally as low as -196 °C) (See Resistance at high and low temperatures).