Stainless steel does not melt at a single temperature but over a range, because it is an alloy of several metals. Alloy 316L melts at 1375-1400degC, duplex Alloy 2205 at 1385-1445degC, and super duplex grades at 1410-1460degC - all below pure iron's 1535degC, since alloying elements lower the melting range.
These figures are ranges rather than absolute numbers because small variations in composition within an alloy can shift the melting point. The relevant grades and designations are:
- Alloy 2205 (1.4462, UNS S32205, UNS S31803, F51, F60, SAF2205)
- Ferralium® 255 (1.4507, UNS S32550)
- UNS S32750 (1.4410, F53, SAF2507)
- UNS S32760 (1.4501, F55, Zeron 100®)
Melting point rarely matters in service
Recommended service temperatures sit well below the melting point, to keep the mechanical and physical properties intact. Melting point mainly concerns the producers, who control process temperatures for melting, casting, forging, rolling and heat treatment such as solution annealing.
In real-world use, the maximum service temperature is usually limited by loss of corrosion and oxidation resistance, loss of strength, and the formation of deleterious intermetallic phases over extended exposure - not by melting.
Melting point is not the only temperature concern
Well before melting, steel loses rigidity and becomes more prone to bending as it heats. High temperatures can also damage the protective oxide layer that keeps stainless steel from rusting, leaving it more susceptible to later corrosion. Stainless steel can be damaged by heat without ever reaching its melting point.