Stainless steels and nickel alloys are widely used because of their resistance to aqueous corrosion but they are families of alloys that also have grades that are most useful at elevated temperatures. Generally “high temperature” is considered to be above 500 Deg C. While each grade may have its own “upper limit”, very few may be used at 1200 Deg C. The operating or design temperature is important in as much as it impacts on the 3 considerations listed below and grade selection must take this in to account.
The requirements of materials used at high temperature may be one or a combination of the following:
- High creep strength (and / or ductility). Often strength parameters may be a secondary consideration for alloys in corrosion applications. However at elevated temperatures, the creep phenomena which is also a function of time, occurs and thus this may become the primary consideration in selecting alloys
- Good resistance to high temperature corrosion, including oxidation. Chromium is the element that makes stainless steels “stainless”. It is also one of the primary elements to impart oxidation resistance. Just as the composition of metal grades may be “designed” to provided creep strength, so too this may apply to afford them the requisite resistance to chemical attack.
- A stable microstructure. The fact that the alloys under consideration operate at elevated temperatures for a period of time, may make them prone to the formation of deleterious phases in the microstructure whilst they are in service. The effect of this could be on mechanical properties or resistance to chemical attack or both.
There are specific grades in the 2 families – stainless steels and nickel alloys – that will have compositions that make them better suited for a specific high temperature application.
We stock a range of items that are well suited for use in many common high temperature industrial applications.