The group of steels of special physical – chemical properties, resistant to corrosion caused by water, atmospheric factors, diluted acids, alkaline solutions.
Steel stainlessness, acid resistance, and heat resistance is obtained by adding chromium and nickel as well as molybdenum in appropriate amount, and for heat resistance steels by adding aluminium, silicon and cerium. At present the steels resistant to corrosion are divided into two groups: stainless steels and heat-resistant steels.
Stainless steels comprise all the steels of high resistance to corrosion, except of the heat resistance ones. Stainless steels are used in the temperatures up to 5000 C. Numbering within the range from 1.40 … – 1.45 …
Heat resistant steels (including the creep resistant ones) show high corrosion resistance including that for oxidation (formation of scale) in the temperatures above 5000 C. Besides, creep resistant steels are required to maintain their mechanical properties on stable level under this conditions. Numbering within the range from 1.47 … – 1.48 …
The main properties of the steels referred to above are: resistance to corrosion in various environment conditions, resistance to high temperatures, low thermal expansion, rigidity, strength, durability, easy-machining and joining.