SS6931 304L Stainless Steel Fitting

304L Stainless Steel Stub Description

304L Austenitic Stainless Steel is an alloy with low carbon content (C ≤0,03%) developed to provide high corrosion resistance and structural stability. The controlled carbon level minimises the formation of chromium carbide in the heat‐affected zones during welding, thereby preventing localised corrosion and maintaining a consistent passive layer. The alloy comprises between 18 and 20% chromium and 8 to 12% nickel, which results in the formation of a chromium oxide surface that repairs itself. This layer quantitatively reduces the likelihood of pitting and crevice corrosion, particularly in chloride‐containing environments. The material exhibits a tensile strength exceeding 485 MPa and an elongation of 40%, providing an equilibrium between mechanical strength and ductility for demanding structural applications. Annealed and pickled surfaces (Ra ≤0,8 μm) facilitate passivation, and optional electropolishing further enhances the surface finish and corrosion resistance.

304L Stainless Steel Stub Applications

• Chemical Processing: Valve shafts, reactor fittings and pump shafts in acidic or alkaline media
• Medical: Handles for surgical instruments and components for implantable devices
• Semiconductors: Wafer handling devices and vacuum chamber components
• Food/Beverage: Fittings for storage tanks and parts for CIP systems
• Marine: Fasteners and couplings exposed to seawater

304L Stainless Steel Stub Packaging

Products are packed in customised cartons of various sizes, determined by the dimensions of the material. Small items are securely packaged in PP cartons, while larger items are placed in custom-made wooden crates. We comply strictly with customer-specific packaging requirements and utilise appropriate cushioning materials to ensure optimal protection during transport.

Packaging: Carton, wooden crate, or as per customer specifications.

Please refer to the Packaging Details for further information.

Manufacturing Process

Testing Procedures

(1) Chemical Composition Analysis – Techniques such as GDMS or XRF verify that the material meets the specified purity requirements.

(2) Mechanical Properties Testing – This testing includes assessments of tensile strength, yield point and elongation to evaluate material performance.

(3) Dimensional Inspection – Measurements of thickness, width and length are taken to ensure compliance with the specified tolerances.

(4) Surface Quality Assessment – Visual and ultrasonic inspections are conducted to identify defects such as scratches, cracks or inclusions.

(5) Hardness Testing – This method determines the material’s hardness and confirms the uniformity of its mechanical properties.

For full details, refer to the SAM Testing Procedures.

FAQs on 304L Stainless Steel Stubs

Q1. Does welding 304L stainless steel require post-treatment to prevent rusting in outdoor conditions?

No. The low carbon content (≤0,03%) limits the formation of chromium carbide during welding, thereby maintaining the corrosion resistance in the heat‐affected zones. Welding disrupts the passive oxide layer; consequently, light sanding of the weld area and the application of a suitable stainless steel cleaner will restore the corrosion protection.

Q2. How can surface discolouration on 304L components be removed without damaging the material?

A non-abrasive stainless steel cleaner or a mild acid solution (for example, a vinegar and water mixture) applied with a soft cloth should be used. Avoid strong chemicals or abrasive tools that may scratch the surface. For significant discolouration, treatment with a passivation gel or electropolishing (performed by a professional service) will restore the chromium oxide layer without altering the dimensions.

Q3. Is 304L resistant to frequent exposure to seawater or swimming pool chemicals?

304L demonstrates good corrosion resistance under general conditions. However, extended exposure to seawater or chlorine may lead to pitting corrosion over time. After exposure, the material should be rinsed thoroughly and regular electropolishing may be considered to improve the surface smoothness. In marine or chemical environments, 316L offers improved chloride resistance; however, 304L is acceptable for occasional exposure provided that appropriate maintenance is observed.

Further Information

Common Treatment Methods

304L rods are processed by vacuum induction melting to control sulphur and phosphorus impurities. The material is hot forged at temperatures between 1 150°C and 1 260°C and subsequently solution annealed at temperatures between 1 040°C and 1 120°C, followed by rapid water quenching to dissolve carbides. The rods are then machined to a tolerance of ±0,05 mm and pickled in an HNO₃/HF bath to remove scale. For medical-grade materials, electropolishing in a phosphoric-sulphuric acid solution achieves a surface roughness of Ra ≤0,4 μm. Final passivation is performed in accordance with ASTM A967 Method 2 to ensure the integrity of the chromium oxide layer. Batch traceability is maintained through PMI verification using XRF and intergranular corrosion testing in accordance with ASTM A262 Practice E.