Material number 1.4305: 1.4305
1.4305 is the European material number (Werkstoffnummer, EN 10027-2) for 1.4305, austenitic free-machining stainless steel (sulphur-bearing) specified in EN 10088-3.
What 1.4305 means
EN 10027-2 material numbers have the form 1.XXYY: the leading 1 is steel; the next two digits give the steel group (43 → stainless steels with ≥ 2.5 % Ni, no Mo); the last two digits are a sequential number within that group. The number is unique to one composition and survives name changes, which is why 1.4305 has stayed constant while the symbolic name moved from X10CrNiS18 9 to 1.4305.
1.4305 at a glance
1.4305 (X8CrNiS18-9) is 18/8 stainless deliberately made dirty: 0.15–0.35 % sulphur forms manganese-sulphide inclusions that break chips and lubricate the tool, giving roughly 80 % of the machinability of free-cutting carbon steel and about double that of 1.4301. It is the grade of every automatic lathe shop that turns stainless fittings, nuts, shafts, valve stems and pins.
The sulphides cost something: pitting resistance drops (PREN nominally the same, but sulphide sites initiate attack), weldability is poor (hot-cracking and porosity), and transverse ductility is low, so 1.4305 is supplied only as bar, wire and hexagons — never as sheet. It is used for parts that see mild environments (indoor, fresh water, food-grade with cleaning) and no welding.
AISI 303, JIS SUS303 and GB Y12Cr18Ni9 are the same steel; the EN specification is slightly tighter on carbon (0.10 vs 0.15 %). For chloride service the free-machining 316 variant is 1.4570 (316F).
Full data sheet for 1.4305 → · Equivalent grades →