What are the materials used for boiler construction ?

Boilers are Constructed out of a variety of materials. 

The Boiler is a device which generates steam at very high pressure and temperature.  Thus, it should be designed to withstand the mechanical and thermal stress caused by the temperature and pressure.

While selecting materials or boilers, there are also issues such as cost and availability which determine the choice.

In general, Low Pressure Boilers are constructed out of cast iron or steel. 

Miniature Boilers can be made of stainless steel or copper while Power Boilers are designed out of special steels which can withstand very high pressure and temperature.