314 Stainless Steel - 1.4841 - X15CrNiSi25-21 - ~SUH 310

314 is an austenitic, heat resistant stainless steel. The addition of silicon in 314 stainless makes this steel grade more resistant to oxidation and prevents carburization at elevated temperatures. On the other hand, continuous use at a temperature range of 1202-1652°F (650-900°C) makes this stainless steel more susceptible to phase changes and embrittlement. This material grade is suitable for cold forming and cold heading, hammer- and die forging and is not magnetizable.

Heat resistance

314 is a heat resistant stainless steel with good oxidation and excellent chemical resistance at temperatures of up to 2012°F (1100°C). However, the corrosion resistance of this heat resistant steel is restricted in certain atmospheres (please see corrosion resistance).

Heat treatment

Solution annealing

Heat the work pieces uniformly to a temperature of 1922-2102°F (1050-1150°C) and then quench the parts in water or cool rapidly in air.

Hardening

This steel grade can only be hardened by cold working it.


Quenching media

• Water
• Air

Hot working

Heat the work piece slowly and uniformly to a temperature range of 1742-2192°F (1200-950°C) and carry out the hot work. Do not let the temperature drop below 1832°F (1000°C) and use an annealing treatment after hot forming, especially if the temperature dropped below 1832°F during hot working the material.

Cold working

Due to its austenitic structure, which makes the material more ductile, 314 stainless steels can be easily cold worked. Parts that have been exposed to high temperatures (1202-1652°F (650-900°C)) over a long time are not recommended to be cold worked as the material becomes susceptible to intergranular carbide precipitation as well as intermetallic phase precipitation.

Corrosion resistance

Intergranular corrosion

With the addition of carbon, this alloy is sensitive to intergranular corrosion after sensitization. Though this stainless steel contains 25% of chromium, which improves corrosion resistance, this alloy is not suitable to be used in wet environments.

Atmospheric corrosion

Above 1202°F (650°C), there already is a limited corrosion resistance to reducing or oxidizing gases with a sulphur content.

Above 1652°F (900°C), 314 has only limited corrosion resistance to carburizing gases or low-oxygen gases with nitrogen content.

Machinability

The formation of carbides, in 314, increases the wear of cutting tools. Due to severe work hardening and poor thermal conductivity, adequate cooling and high quality tooling is required. 314 stainless steels should be machined at a low cutting speed with shallow cutting depths.

Forging

Heat the parts up to a temperature range of 2147-1832°F (1175-1000°C) and finish the process by rapidly cooling the pieces in water or air.

Welding

As austenitic steels in comparison to unalloyed steels only have a 30% thermal conductivity and a lower fusion point, austenitic steels should be welded with a lower heat input than unalloyed steels. To avoid burn through or overheating of thinner parts it is recommended to apply a higher welding speed. 314 stainless steels have a much higher coefficient of thermal expansion than unalloyed steels. Combined with poorer thermal conductivity greater distortion is to be expected.