INOX – Steel processing guide
3- PHYSICAL AND MECHANICAL PROPERTIES
Stainless steels have a wide range of both physical and mechanical properties for the most disparate application situations.
The specific weight is variable depending on the different chemical composition and is between 7,7 gr/cm3 for martensitic and ferritic grades and 8,06 gr/cm3 for austenitic.
For thermal conductivity, it must be noted that ferritic and martensitic steels conduct heat better than austenitic steels; also the electrical resistivity is greatly differentiated between the austenitic, where it is higher than in other types.
Also to consider is the coeflìcient of thermal expansion: austenitic dilate much with temperature, compared to the other stainless steels.
Finally, also different is the relative magnetic permeability, in fact, the martensitic and ferritic families are substantially ferromagnetic, while that is non-magnetic austenitic. For this the first physical characteristic is not very influenced dall’incrudimento by cold deformation, while the austenitic are affected much more than this phenomenon.
They are different depending on the different types and can be summarized as follows:
The austenitic grades are not likely to raise their characteristics by quenching and consequently have no high-strength qualities. They are however able to also raise very their resistance by work hardening by cold plastic deformation, by raising the tensile strength, the yield strength and decreasing the elongation at break. This phenomenon is exploited very precisely in the cold molding of these materials. They possess high fatigue resistance characteristics. That shock is very high, both at room temperature, both at very low temperatures.
Also ferritic grades are not likely to hardening treatment and consequently are not high-strength characteristics. The work hardening by cold plastic deformation also increases in this case the characteristics of resistance, but to a lesser extent compared to austenitic.
The martensitic types offer the best mechanical resistance of stainless steels when they are put in place when hardened (quenching and tempering).
In table 2 we have been listed some of the physical and mechanical characteristics of the most significant of the main most used stainless steels.
Table 2 – Some physical and mechanical characteristics of stainless steels shown in Table 1.