What is the difference between V2A and V4A?

The designations V2A and V4A are used by industry professionals to refer to groups of corrosion-resistant stainless steels belonging to the austenitic class. These materials feature a face-centred cubic crystal structure stabilised by the alloying elements chromium and nickel. We use these materials because they offer excellent formability and weldability. While V2A serves as the standard alloy for general requirements, V4A is a higher-grade variant. Through targeted metallurgical modifications, both variants fulfil specific roles in modern surface finishing and structural engineering.

Designations and synonyms

Stainless steel is identified using various international standards systems, each of which addresses specific details of the alloy. In our production, we primarily use the numerical material designations specified in DIN EN 10088 to ensure maximum precision in material procurement and processing.

V2A – material grade 1.4301 and AISI 304

The designation V2A originates from the historical test series “Versuchsschmelze Austenit 2” (Austenite Test Melt 2). In modern standards, it primarily corresponds to grade 1.4301. Internationally, this grade is known as AISI 304 (American Iron and Steel Institute). We also offer variants such as 1.4307, a low-carbon version (304L) that provides improved corrosion resistance after welding. This alloy is the mainstay of standard applications in interior fit-outs and general mechanical engineering where environmental conditions are moderate.

V4A – material grade 1.4401/1.4404 and AISI 316/316L

V4A stands for the fourth test series and today includes grades such as 1.4401 and 1.4404. In English-speaking countries, these molybdenum-bearing stainless steels are designated AISI 316. Grade 1.4404 (316L) has a reduced carbon content, which minimises susceptibility to intergranular corrosion. We recommend this grade for projects in coastal locations or chemically aggressive environments. Titanium-stabilised stainless steel 1.4571 also falls under the collective term V4A, but is increasingly being replaced by 1.4404, which is easier to polish.

Chemical composition

The performance of the materials is directly determined by their chemical composition. We monitor compliance with these limits in accordance with ISO 9001 to ensure the reproducibility of our surface finishes.

Chromium (Cr): 17.5% to 19.5% (ensures the formation of the protective passive layer)

• Nickel (Ni): 8.0% to 10.5% (stabilizes the austenitic microstructure and improves toughness)
• Carbon (C): Maximum 0.07% for standard grades, below 0.03% for L grades (reduces carbide formation)
• Molybdenum (Mo): Only present in V4A, approx. 2.0% to 2.5% (increases resistance to chlorides)
• Manganese (Mn): Maximum 2.0% (supports desulfurization during melting)
• Silicon (Si): Maximum 1.0% (used to deoxidize the steel)

Properties

The physical and mechanical properties of V2A and V4A determine their suitability for complex forming processes and static loads. We take these values into account at every finishing stage at our plant in Cleebronn.

Mechanical Properties

Both stainless steel grades have a yield strength of approximately 200 to 230 MPa and a tensile strength of between 500 and 700 MPa. Their elongation at break is a high 40 % to 45 %, enabling excellent cold formability. We use this ductility to create complex textures such as our VIBES or BEADS finishes. Despite their moderate hardness of approx. 160 to 200 HB (Brinell), the materials are tough and resistant to impact loads. Where required, we increase their strength through work hardening during the rolling processes.

Physical Properties

Stainless steel has a density of approx. 7.9 kg/dm³ and a thermal conductivity of 15 W/(m·K), which is significantly lower than that of unalloyed structural steel. Its electrical resistivity is comparatively high at approx. 0.73 (Ω·mm²)/m. In thermal processing and façade construction, we take into account the linear thermal expansion coefficient of 16.0 to 16.5 x 10⁻⁶ K⁻¹. This causes components to expand when exposed to sunlight. Our design recommendations account for these physical constants to reliably prevent stress cracking in large-area cladding.

Corrosion resistance

This is the key differentiating factor: While V2A offers good resistance to water, water vapour and humidity, V4A provides protection against aggressive media. The molybdenum content in V4A significantly increases the PREN value (Pitting Resistance Equivalent Number). This prevents pitting corrosion in chloride-containing environments such as swimming pools or marine applications. We use V4A where contact with de-icing salts or industrial acids is unavoidable. In both grades, the passive layer regenerates automatically upon contact with oxygen after mechanical damage.

Magnetism

In the solution-annealed condition, both V2A and V4A are non-magnetic (antimagnetic). This is an essential characteristic for applications in medical technology or electronics manufacturing. However, please note that cold working—such as bending, deep drawing or polishing—can cause some strain-induced martensite to form. This results in the material becoming slightly magnetic. The greater the degree of forming, the stronger this effect. Due to its higher nickel and molybdenum content, V4A is less susceptible to magnetisation through cold working than V2A stainless steel.

Applications and Industries

The applications of V2A and V4A overlap to some extent, but are clearly differentiated by economic and technical considerations. We supply customers worldwide across a wide range of industrial sectors with specialized finishes.

• Architecture and façade construction: V2A for interiors, V4A for exterior envelopes in urban or marine environments.
• Food industry: V2A for vessels, tanks and work surfaces not exposed to high salt concentrations.
• Chemical industry: V4A for piping and equipment that come into contact with acids or chlorides.
• Yacht and shipbuilding: Exclusive use of V4A for railings, fittings and polished design elements.
• Pharmaceutical industry: V4A (often 1.4435) for sterile production facilities with the most stringent purity requirements.
• Elevator construction: V2A for cabin walls and control panels in standard buildings without corrosive exposure.

Overview of international standard designations

Knowledge of international equivalents is essential for global trade and precise specification in export projects. We supply our products worldwide and ensure that all materials comply with the required standards.

• Germany/Europe: Material grades 1.4301 (V2A) and 1.4404 (V4A) in accordance with DIN EN 10088.
• USA: AISI 304/304L (V2A) and AISI 316/316L (V4A) in accordance with ASTM standards.
• Japan: SUS 304 and SUS 316 in accordance with JIS (Japanese Industrial Standards).
• China: 06Cr19Ni10 (V2A) and 022Cr17Ni12Mo2 (V4A) in accordance with GB/T standards.
• United Kingdom: British Standard (BS) designations such as 304S15 or 316S11.

Finishing V2A and V4A – Precision by mirrorINOX

At our plant in Cleebronn, we transform standard stainless steel sheets into functional works of art. We process both V2A and V4A in thicknesses ranging from 0.5 mm to 30 mm. With our proprietary Perfect Mirror No. 10® finish, we produce the world’s highest-quality mirror polish, which is even used for optical measuring instruments. Using the nanoINOX® process, we apply functional coatings that combine anti-fingerprint properties with brilliant colours. Our mechanical finishing processes, such as glass bead blasting (BEADS) and vibratory finishing (VIBES), guarantee perfect reproducibility from batch to batch. Thanks to our ISO 9001 certification and state-of-the-art equipment, we ensure consistently high quality for every project.