1.4307 seamless stainless pipe is the European (EN/DIN) designation for a low carbon austenitic stainless steel grade, equivalent to UNS S30403 and ASTM A312 TP304L. This grade is specifically designed for applications requiring excellent corrosion resistance combined with superior weldability, particularly where post-weld heat treatment is not practical or desired.

The "1.4307" designation follows the EN 10088 and EN 10216-5 standards, which govern seamless stainless steel pipes for pressure and general purposes. The corresponding material number 1.4307 identifies a composition of 17.5-19.5% chromium and 8-10% nickel, with a maximum carbon content of 0.030%. The material name is X2CrNi18-9, where "X" indicates high-alloy steel, "2" indicates very low carbon (0.030% max), "CrNi18-9" indicates 18% chromium and 9% nickel.

The low carbon content is the defining characteristic of 1.4307. Standard austenitic grades with higher carbon content (such as 1.4301 / X5CrNi18-10) can experience sensitization – the precipitation of chromium carbides at grain boundaries during welding or elevated temperature service. This sensitization depletes chromium adjacent to the grain boundaries, making the material susceptible to intergranular corrosion (weld decay). 1.4307's 0.030% maximum carbon content virtually eliminates this risk, allowing the material to be welded without post-weld heat treatment while maintaining its corrosion resistance throughout the heat-affected zone.

The low carbon content is the defining characteristic of 1.4307, distinguishing it from 1.4301.

Explanation of EN material names:

Comparison with other EN grades:

1.4307 seamless stainless pipe delivers the following mechanical properties in the solution annealed condition:

High-Temperature Mechanical Properties (Typical):

Maximum allowable service temperatures (EN 10216-5):

Low-Temperature Impact Properties:

1.4307 maintains excellent toughness down to cryogenic temperatures, making it suitable for low-temperature and cryogenic service down to -196°C.

1.4307 seamless stainless pipe conforms to multiple European and international standards:

The seamless manufacturing process for 1.4307 pipe follows EN 10216-5 requirements.

Step 1 – Billet Preparation
Solid round billets of 1.4307 composition are inspected, cut to length, and heated to approximately 1200°C.

Step 2 – Piercing (Hot forming)
The heated billet is fed into a piercing mill where a conical mandrel forces through the center, creating a hollow shell (rotary piercing process).

Step 3 – Elongation
The hollow shell passes through a mandrel mill with multiple rolling stands to reduce wall thickness and increase length.

Step 4 – Sizing and Reducing
The pipe passes through a sizing mill or reducing mill to achieve precise outer diameter and straightness.

Step 5 – Cold Drawing (optional)
For tighter dimensional tolerances and superior surface finish, the hot-finished pipe is cold drawn through a die and over a mandrel. Multiple cold drawing passes with intermediate annealing are employed for small diameters and thin walls.

Step 6 – Solution Annealing
The pipe is heated to 1020-1120°C (1870-2050°F) and then water quenched. This step dissolves chromium carbides, restores corrosion resistance, and achieves the required mechanical properties.

Step 7 – Descaling (Pickling)
Scale and oxide layers are removed using a nitric-hydrofluoric acid pickling bath, producing the standard 1E (annealed & pickled) finish.

Step 8 – Bright Annealing (optional)
Final annealing in a controlled hydrogen or nitrogen atmosphere produces an oxide-free, bright surface (2R finish).

Step 9 – Straightening and Finishing
The pipe is straightened using rotary straighteners, cut to specified lengths, and ends are prepared (plain, beveled, or threaded).

Step 10 – Testing and Inspection
Hydrostatic testing, non-destructive examination (NDE), dimensional checks, and surface inspection are performed.

For inquiries, technical data sheets, or a quotation for 1.4307 seamless stainless pipe (X2CrNi18-9 / EN 10216-5 / low carbon stainless steel pipe), please contact our sales team.