NBN ISO 4955:2021

This International Standard specifies requirements for the grades listed in Table 2, which are
usually employed for products for which the resistance to the effects of hot gases and the products of
combustion at temperatures in the region above 550°C and/or to long-term mechanical stress is the
main requirement.
NOTE 1 Grades mentioned in this International Standard may also be used for corrosion and creep resistant
purposes.
This International Standard is applicable to the following:
— flat products;
— bars, sections, rod, semi-finished products and forgings.
NOTE 2 Hammer-forged semi-finished products (blooms, billets, slabs, etc.), seamless rolled rings and
hammer-forged bars are in the following, covered under semi-finished products or bars and not under the term
“forgings”.
NOTE 3 Not all of the grades included in this International Standard are necessarily available in all
product forms.
NOTE 4 In Table 2, two alloys are listed in addition to the steels since they belong to the heat resistant grades.
NOTE 5 Heat resistant wire in the cold worked condition is covered by ISO 16143-3.
NOTE 6 Corrosion resistant stainless steels for which resistance to corrosion is of primary importance are
covered by ISO 16143-1 and ISO 16143-2.
NOTE 7 Heat-resistant steels for valves are covered by ISO 683-15.
In addition to this International Standard, the general technical delivery requirements of ISO 404 are
applicable.