High-grade steel is the primary material of choice in vacuum technology. It has sufficient strength even during
bake-out processes, can be welded vacuum-compatibly and its surface is sufficiently protected for numerous
application areas.
Overview of all common high-grade steels and their composition.

Table for chemical composition (as a %) of high-grade steel as per ISO 3506 / EN 10 088-3

Table of properties of high-grade steels

Description of individual high-grade steel types

1.4301:
Austenitic stainless steel. Very high cold formability. Easily weldable. High corrosion resistance. Polishable.
Highly suited for vacuum applications.
1.4305:
Easy to machine. Lower corrosion resistance than 1.4301. Not weldable. Moderately suitable for vacuum applications.
1.4306, 1.4307:
Low-carbon variant of 1.4301 with similar properties. Highly weldable due to low carbon level, very insusceptible
to intergranular corrosion. Highly suited for vacuum applications.
1.4401:
Very high cold formability. Easily weldable. Due to molybdenum additive, more resistant than 1.4301 to nonoxidising
acids and chlorine compound, polishable, well suited for vacuum applications.
1.4404:
Significantly less carbon than 1.4401 but with similar properties. Highly weldable due to low carbon level, very
insusceptible to intergranular corrosion. Highly suited for vacuum applications.
1.4429:
Similar properties to 1.4435 but higher strength due to higher nitrogen share. The nitrogen share also stabilises
the austenitic structure. Highly suited for vacuum applications.
1.4435:
Similar properties to 1.4404. The increased share of molybdenum makes 1.4435 more resistant to non-oxidising
acids and media containing chlorine than 1.4404. Highly suited for vacuum applications.
1.4541:
Similar properties to 1.4301 but not polishable. Titan-stabilised, which makes is highly weldable in all dimensions
without being susceptible to intergranular corrosion. Well suited for vacuum applications.
1.4571:
Similar properties to 1.4401. Titan-stabilised, which makes is highly weldable in all dimensions without being
susceptible to intergranular corrosion. Not polishable. Well suited for vacuum applications.
1.4429 ESR:
Very high homogeneity including purity combined with a high hardness level. Of particular importance is its very
low magnetic permeability. Other properties correspond to 1.4429 although highly suitable for vacuum applications.

Properties of typical flouroplastic seals