Stainless Steel is a general term describing a wide range of steel alloys – each of which has a different specific make-up.
As stainless steels are an alloy of several different metals, the melting point of stainless steel happens over a temperature range rather than at a specific temperature. Also, the addition of alloying elements to iron acts to reduce the melting temperature range.
Pure iron has a melting point of 1535degC, but for Alloy 316L it is 1375-1400degC, 1385-1445degC for duplex Alloy 2205 (1.4462, UNS S32205, UNS S31803, F51, F60, SAF2205) and 1410-1460degC for super duplex stainless steels such as Ferralium 255 (1.4507, UNS S32550), UNS S32750 (1.4410, F53, SAF2507) and UNS S32760 (1.4501, F55, Zeron 100).
These melting points are expressed as a range rather than an absolute number because even within a specific alloy of stainless steel, there is the possibility that small variations in the formation could affect the melting point.
The recommended service temperatures for these alloys is significantly below their melting point in order to retain their favourable mechanical and physical properties.
The melting point of stainless steel is normally only of consideration to the producers, who need to control process temperatures for melting, casting, forging and rolling, plus subsequent heat treatment such as solution annealing. When it comes to their real-world applications, the maximum temperature of use may be limited by their reduction in corrosion and oxidation resistance, retention of strength and avoiding the formation of deleterious intermetallic phases if exposed for extended periods.
At extremely high temperatures, many materials start to lose their tensile strength, with stainless steel being no exception. Even before melting point is reached for stainless steel, the metal itself becomes less rigid and more susceptible to bending when heated.
The exposure to high temperatures can affect the protective oxide layer which keeps stainless steel from rusting which makes it more susceptible to future corrosion.
So, even if your stainless steel does not reach melting point, the high temperatures could still result in damage.
If you have any more questions about stainless steel, please contact Langley Alloys today. Our friendly and knowledgeable team can answer any questions that you may have and can also advise you on the best solution for your application.