— 01
Realistic multi-phase cycle
Alternates salt spray, condensing humidity and dry atmosphere — simulating the real-world exposure of an automotive part: rain → drying → spray → overnight condensation.
VDA 621-415 test
on disc springs
The standard cyclic corrosion test of the German automotive industry (Verband der Automobilindustrie). One cycle combines 24 h salt spray + 96 h humid-tropical exposure + 48 h standard atmosphere. Run on 14 samples — stainless steels 1.4310 and 1.4568 plus standard steel 51CrV4 with eight anti-corrosion coatings.
4 full cycles on all samples and 13 extended cycles on four selected stainless samples. Compared in parallel against immersion in 3% NaCl and 40% MgCl₂ to calibrate the test against standardized immersion media.
Time distribution of the three phases within one VDA cycle — most of the cycle (96 h, 57%) takes place under tropical condensation, where the failure modes most relevant to automotive applications appear.
Cycle
168 h · 7 d
Standard
4 cycles · 4 wk
Extended
13 cycles · 91 d
Samples
14 · stainless + coatings
01
Structure of a VDA 621-415 cycle
| # | Phase | Duration | Standard | Conditions | Dominant mechanism |
|---|---|---|---|---|---|
| 01 | Salt spray | 24 h | DIN 50021 SS | 35 °C · continuous spray · 5% NaCl | Accelerated salt attack · first chloride load on the surface |
| 02 | Humid-tropical | 96 h | DIN 50017 KFW | 40 °C · 100% RH · condensation on the part | Condensing atmosphere · constant moisture · activates corrosion beneath the coating |
| 03 | Standard atmosphere | 48 h | DIN 50014 | 23 °C · 50% RH | Laboratory climate · drying · partial recovery before the next cycle |
Total · 1 cycle: 168 h · 7 days per cycle — the transitions between phases subject the part to changes in temperature, relative humidity and chemical attack.
— Why VDA is the benchmark
— 02
High reproducibility
All three phases are standardized (DIN 50021, DIN 50017 KFW, DIN 50014). This makes it possible to compare results across labs and over time.
— 03
OEM acceptance
Many qualification specifications across the automotive supply chain require a minimum number of VDA cycles before a component or a coating can be approved.
02
Applying the test to disc springs
Samples: the same geometries and materials used in the rest of the corrosion tests, to ensure direct comparability across blocks.
Mechanical state: parts free of load throughout the test, with no preload and no fatigue cycling. The results reflect the intrinsic resistance of the material or coating to the VDA cycle, with no influence from internal stresses.
Parallel tests: at the same time, the same materials and coatings were subjected to 4 weeks of immersion in 3% NaCl and 40% MgCl₂. This makes it possible to calibrate VDA against two standardized immersion media and to understand whether a material that passes VDA also withstands more concentrated chloride exposure.
| Parameter | Value |
|---|---|
| Type of exposure | Cyclic · 3 alternating phases per cycle |
| Cycle duration | 168 h (7 days) |
| Standard duration | 4 cycles · 4 weeks · on all samples |
| Extended duration | 13 cycles · ~91 days · on 4 stainless samples |
| Mechanical state | Parts free of load · no preload, no fatigue |
| Geometries | C-63 (63×31×1.8 mm) · B-80 (80×41×3.0 mm) · DIN 2093 |
| Parallel tests | 4-week immersion in 3% NaCl and 40% MgCl₂ for calibration |
Stainless steels · 6 variants
- 01 1.4310 · standard
- 02 1.4310 · shot peened
- 03 1.4568 · standard
- 04 1.4568 · shot peened
- 05 1.4568 · Kolsterised
- 06 Series C-63 and B-80
51CrV4 steel + 8 anti-corrosion coatings
- 01 Yellow zinc plating
- 02 Clear zinc plating
- 03 Dacromet
- 04 Geomet
- 05 Delta Tone + Delta Seal
- 06 Nickel plating
- 07 Water-based paint
- 08 Oiled
03
Results after 4 VDA cycles
Absolute VDA result · level difference vs. immersion in 3% NaCl and 40% MgCl₂
Scale
Good
Moderate
Poor
Very Poor
How to read the NaCl / MgCl₂ columns+1one level better than VDA= 0same level as VDA−1one level worse−2two levels worse−3three levels worse
| Spring · Material · Finish | VDA4 cycles · absolute | NaCl 3%immersion · diff vs VDA | MgCl₂ 40%immersion · diff vs VDA |
|---|---|---|---|
| — Uncoated stainless steels | |||
| C-63 · 1.4310 · Stamped · Ground | = 0 | +1 | |
| C-63 · 1.4310 · Shot peened | = 0 | +1 | |
| B-80 · 1.4310 · Stamped · Ground | = 0 | +1 | |
| C-63 · 1.4568 · Stamped · Ground | −1 | = 0 | |
| C-63 · 1.4568 · Shot peened | −1 | = 0 | |
| C-63 · 1.4568 · Kolsterised | −1 | = 0 | |
| — 51CrV4 steel with anti-corrosion coatings | |||
| 51CrV4 · Yellow zinc plating | −1 | −3 | |
| 51CrV4 · Clear zinc plating | −1 | −2 | |
| 51CrV4 · Dacromet | = 0 | = 0 | |
| 51CrV4 · Geomet | = 0 | = 0 | |
| 51CrV4 · Delta Tone + Delta Seal | = 0 | −1 | |
| 51CrV4 · Nickel plating | = 0 | = 0 | |
| 51CrV4 · Water-based paint | −2 | −2 | |
| 51CrV4 · Oiled | = 0 | = 0 | |
Conditions: 4 full VDA cycles (28 days) · parts free of load · compared with 4 weeks of immersion in 3% NaCl and 40% MgCl₂ at room temperature.
Shall we talk about your project?
Tell us your use case and our engineering team will advise you on choosing the optimal solution.
04
Images of the samples after 4 VDA cycles
14 springs · color chip = VDA result on the B / M / P / MP scale
Medio Stainless steels · 6 variants
1.4310 · C
C-63 · 1.4310 · Stamped · Ground
1.4310 · C · SP
C-63 · 1.4310 · Shot peened
1.4310 · B
B-80 · 1.4310 · Stamped · Ground
1.4568 · C
C-63 · 1.4568 · Stamped · Ground
1.4568 · C · SP
C-63 · 1.4568 · Shot peened
1.4568 · C · KO
C-63 · 1.4568 · Kolsterised
Medio 51CrV4 steel with 8 coatings
Zinc plated · Yellow chromate
Yellow zinc plating
Zinc plated · Clear chromate
Clear zinc plating
Dacromet
Dacromet
Geomet
Geomet
Delta Tone + Seal
Delta Tone + Delta Seal
Nickel plating
Nickel plating
Water-based paint
Water-based paint
Oiled
Oiled
05
Reading the results after 4 cycles
Stainless steels
1.4310 (with and without shot peening, in C and B): good result (B). The shot-peened part shows no sign of corrosion; the two without shot peening show small brown spots, but the overall condition is rated good.
1.4568 standard: moderate (M) — behavior similar to a 1.4310 without shot peening, with somewhat more staining.
1.4568 shot peened: poor (P). Shot peening, far from improving it, makes it worse. Shot peening introduces roughness without any electrochemical offset — a pattern already seen in the unstressed test.
1.4568 Kolsterised: very poor (MP). It is the worst stainless steel evaluated — the surface is covered with deep brown spots. Kolsterising improves wear resistance, not chemical resistance to VDA cycles.
Coatings on 51CrV4
Dacromet and Geomet: good (B), with no signs of corrosion after 4 cycles. They match the best stainless steel and confirm their versatility against saline atmospheric environments.
Delta Tone + Delta Seal: moderate (M). White spots appear (zinc corrosion products) without the base steel being affected — the sacrificial layer is still working.
Clear zinc plating: poor (P) — brown spots and abundant white spots.
Yellow zinc plating: very poor (MP) — a large number of deep brown spots with base-steel corrosion clearly visible.
Electroless nickel and water-based paint: both poor (P). The defects appear at the edges — the base steel corrodes wherever the coating is discontinuous.
Oiled: very poor (MP), as expected. Oil is storage protection, not real corrosion protection.
06
VDA versus chloride immersion
— 1.4310
VDA more demanding than immersion
For the 1.4310 samples, VDA stresses the part more than 3% NaCl (same level) and even more than 40% MgCl₂ (+1). In immersion there is no localized condensation or evaporation zones that concentrate chlorides on the part.
— 1.4568
NaCl immersion more aggressive than VDA
Across all 1.4568 variants, 3% NaCl is one level worse than VDA. This reflects the particular sensitivity of 17-7 PH to dissolved chlorides under continuous exposure versus atmospheric cycling.
— Zinc · MgCl₂
Zinc dissolves in 40% MgCl₂
Yellow and clear zinc plating: substantially harsher punishment in 40% MgCl₂ (−2 and −3 relative to VDA). The high concentration of dissolved chlorides dissolves the zinc of the coating.
— Dac · Geomet · Aceitado
Same level in VDA and immersion
All three tests give an identical level: B for Dacromet and Geomet, MP for oiled. These are cases where the failure mode does not depend on the type of exposure, only on the medium.
— Pintura agua
Immersion dissolves the paint
The immersion tests are significantly more aggressive than VDA (−2 in both). Continuous immersion dissolves the organic layer; in VDA, the dry phases let the paint partially recover between cycles.
07
Extended test · 13 cycles on stainless steels
9 additional cycles on 4 variants that had performed well over the first 4 cycles · ~91 days total
To assess long-term behavior, the test was extended on four selected stainless variants — the ones that had performed best over the first 4 cycles — completing a total of 13 VDA cycles (~91 days) per part.
The 1.4568 parts show lower resistance than the 1.4310 parts during the extended test. The difference is especially marked in the shot-peened 1.4568, which ends up more degraded than any of the other three. The shot-peened 1.4310 remains the part in the best condition.
This trend confirms a recurring conclusion: 1.4310 offers better overall resistance to atmospheric corrosion than 1.4568, and shot peening benefits 1.4310 but penalizes 1.4568 — a counterintuitive combination if you look only at the higher mechanical strength of 1.4568, but one that reflects the different response of the two steels to cyclic chemical stress.
-
1
C-63 · 1.4310 · Shot peenedBest overall condition after 13 cycles · surface almost clean
-
2
C-63 · 1.4310 · Stamped · GroundGood condition · small isolated brown spots
-
3
C-63 · 1.4568 · Stamped · GroundSpread staining · lower resistance than any 1.4310
-
4
C-63 · 1.4568 · Shot peenedMore degraded than the other three · visible pitting
The 4 stainless variants tested: C-63 · 1.4310 standard and SP · 1.4568 standard and SP.
08
VDA test conclusions
— Stainless steels
The 1.4310 grades are the most reliable under cyclic exposure
With shot peening, the result is optimal both short-term (4 cycles) and long-term (13 cycles). First choice when VDA is the qualification criterion.
— Dac · Geomet
They match the best stainless steel over 4 VDA cycles
The most versatile option when cost is a factor or the starting point is carbon steel. Beyond 4 cycles, it is best to validate with an extended test.
— 1.4568
The most vulnerable among the stainless steels
Especially shot peened or Kolsterised. If the application requires it mechanically, combine it with an additional coating or limit environmental exposure.
— Zinc plating
Below Dacromet / Geomet in VDA
For automotive applications that must pass several VDA cycles, mechanical galvanizing is not the optimal choice.
— Geometry
Nickel plating and paint: they fail at the edges
The failure mode is not chemical but one of coating uniformity over geometries with sharp edges like those of the disc spring.
Cross-reference with the other blocks. For automotive applications and components exposed to de-icing salts or coastal environments, this test is a direct qualification benchmark. For applications under static or dynamic load, the VDA results must be cross-checked with the stressed and fatigue tests — where the conclusions can change significantly.
09
Applications where VDA is a direct benchmark
The VDA 621-415 test is one of the most widespread qualification criteria across the European automotive supply chain. Its use, however, is not limited to that sector: any component exposed to wet-and-dry cycles in saline or industrial atmospheres benefits from being evaluated under VDA rather than under continuous salt spray or immersion.
The final choice of material and coating must cross-check the results of all four test blocks. A fatigue or static-load condition can rule out combinations that look optimal under pure VDA — and vice versa.
Suspension and chassis components in automotive applications · direct road exposure
Wheel fasteners and elements subjected to de-icing salts in cold climates
Springs in engine and powertrain modules · semi-exposed to splash
Equipment in coastal environments · atmospheres with airborne marine chlorides
Outdoor machinery components with wet-and-dry cycles
Any part that must meet OEM specifications with a minimum VDA cycle criterion
10
Frequently asked questions
01 What is the difference between the VDA test and a simple salt spray test?
A simple salt spray test to DIN 50021 (Salt Spray Test / ASTM B117) subjects the part to continuous salt spray exposure at constant temperature and humidity. The VDA 621-415 test combines three alternating phases: 24 h of salt spray + 96 h of humid-tropical exposure (condensing humidity at 40 °C) + 48 h of standard atmosphere (23 °C, 50% RH). This alternation reproduces in-service behavior more realistically — wet-and-dry cycles, condensation, partial recovery between exposures — and often reveals failure modes (filiform corrosion, delamination, hydrogen embrittlement in specific areas) that continuous salt spray does not detect. That is why it is preferred in the European automotive industry as a qualification criterion.
02 How many VDA cycles must a component pass to be considered suitable for automotive use?
It depends on the OEM's qualification specification and the component's position in the vehicle. Typical specs require between 2 and 6 VDA cycles with no visible corrosion failure on the base steel for non-structural functional components; between 6 and 10 cycles for components exposed to splash or de-icing salts; and more than 10 cycles for critical suspension, chassis or wheel-fastener components. Extended 13-cycle tests (~91 days) serve to distinguish between materials and coatings that pass the strictest specs. The exact figure and acceptance criteria are always set by the end customer.
03 If a part passes the VDA test, does that mean it will also pass immersion in 3% NaCl or 40% MgCl₂?
Not necessarily — the failure modes are different. The results on this page show that some combinations pass VDA but fail in immersion (water-based paint, zinc plating in 40% MgCl₂) and, conversely, the 1.4310 stainless steels suffer more in VDA than in continuous immersion because tropical condensation concentrates chlorides locally. The practical rule: VDA is the benchmark for cyclic atmospheric exposure; immersion is necessary when the component operates submerged or in prolonged contact with chloride-laden liquids. The two tests are complementary, not interchangeable.
04 Why does shot peening improve 1.4310 but worsen 1.4568 in the VDA test?
Shot peening introduces residual compressive stresses at the surface and increases roughness. In 1.4310 (a stable austenitic grade) the compressive stresses hinder pit initiation and improve behavior against cyclic atmospheric corrosion. In 1.4568 (17-7 PH, hardenable semi-austenitic) the roughness introduced by peening outweighs the electrochemical benefit — the deformed zones are anodic relative to the rest and become corrosion initiation sites. It is a pattern already documented in the unstressed test: shot peening should never be applied to 1.4568 when corrosion is the dominant criterion.
05 Is the VDA 621-415 test still the current standard, or has it been replaced?
VDA 621-415 is still in force and widely used, especially among suppliers in the German automotive chain. In parallel, some OEMs have adopted the newer cyclic tests derived from ISO 16701 (Cyclic Corrosion Test, CCT) and their own internal standards (Volkswagen's PV 1210, VDA 233-102, etc.) that combine more phases and varying temperatures. For new components, the usual practice is to consult the customer's specific specification. Even so, the results published here remain valid as a technical reference: they compare materials and coatings under the original VDA cycle, which has the longest history and the largest number of qualification specifications associated with it.
Shall we talk about your project?
Tell us your use case and our engineering team will advise you on choosing the optimal solution.