For strength, corrosion resistance and the ability to withstand temperatures up to 2000 F, alloy SST-309 is the best stainless steel alloy. It also has the ability to resist oxidation. For certain applications the only choice is SST-309 over alloy SST-304.

It is especially ideal for applications where it will be exposed to extremely high temperatures. Some of the most common uses for alloy SST-309 at in fire box sheets, furnaces, and the inside boxes of ovens and boilers.

Alloy SST-309 hardens rapidly. It also tends to produce stringy chips when machined. The way to avoid these problems is to use machine without pauses and to use chip breakers.

Oxyacetylene welding should be used at all with this type of alloy. However, alloy SST-309, responds well to fusion or resistance methods of welding. Again, this is an austenitic alloy and as such can be welded very easily.

The best working temperature for Alloy SST-309 is 2150F. If the temperature drops to 1800 F it should be reheated before work continues. When finishing work is completed, water quenching will provide the rapid cooling required by this alloy.

This alloy of stainless steel can be cold worked using such methods as stamping. It can also be drawn, upset or headed, although it does require water quenching at temperatures of 1900 to 2050 F for full annealing. This ensures that any internal stress created by the cold working is eased upon completion of the work.

Alloy SST-309 does not respond well to heat treatment for hardening. It is for this reason that cold work is most often recommended for producing an application with ideal strength and hardness.

To learn more about the stainless steel alloy SST-309.