Cyclic corrosion testing of materials & components in automotive construction.
The purpose of this test is to provide an accelerated test procedure for the assessment of the corrosion behaviour of components and of the corrosion protection provided by coating systems. The test method is based on real corrosive conditions and delivers differentiated results for a large number of uses in automotive applications
Test specimens are placed in an enclosed chamber, and positioned at an angle of 65° to 75° to the horizontal with the side to be tested uppermost. The salt spray phase is performed with a 1% solution of sodium chloride, (pH 6.5 to 7.2) and falls out onto the specimens at a rate of 2.0 to 4.0ml/80cm²/hour.
A full test cycle lasts 7 days and consists of:
Cycles A,B & C are multi step cycles consisting of varying degrees of temperature from -15°C to +50°C and humidity values of between 50% and 95%.
The typical test duration is six full test cycles. (6 Weeks)
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The VW Volkswagen PV 1078 Test Specification defines the assessment criteria for the corrosion resistance of surface-protected, Corrosive highly stressed chassis components based on iron materials, especially low-alloy steels, solid (e.g. subframes, wishbones, cross struts).
Its a two part test, a combination as follows:
- INKA Component Test
- Step 1 Dry phase @ 40°C/40%RH for 4 hours
- Step 2 Salt Spray Phase @ 35°C for 0.5 hours
- Step 3 Wetting Phase @ 40°C/95%RH for 7.5 hours
- Step 4 Dry phase @ 40°C/40%RH for 4 hours
- Step 5 Controlled Humidity @ 50°C/80%RH for 8 hours
- Alternating Climate Test in accordance with PV 1200 (+80°C/-40°C)
- Limit temperatures: 80°C and -40°C
- Holding time at limit temperature: 4 h
- Heating-up and cooling-down times: 2 h
- Relative humidity at 80°C/80%RH
Both the above tests can be ran in a single Ascott chamber
1 cycle lasts one week and is divided as follows:
A: A: B: B: A: A: A, where:
A = INKA component test,
B = storage according to PV 1200.
The start of the test is always “A” with 5 consecutive days.
The test duration for subframes and cavity-forming chassis parts is 6 cycles (this corresponds to 6 weeks).
this is a VW Volkswagen / Audi Test Standard. Also see PV 1209 & PV 1200.
Hyundai/Kia CCT-D
An accelerated corrosion test under complex environment shall be performed in accordance with CCT-D of MS600-66
Step 1: Salt Dipping (Immersion) @ 50°C for 2 hours
Step 2: Wetting @ 50°C / 95%RH for 8 hours
Step 3: Drying @ 70°C / 30%RH for 1.5 hours
Step 4: Drying @ 70°C / 15%RH for 1.5 hours
Step 5: Wetting @ 35°C / 100%RH for 6.5 hours
Step 6: Drying @ 35°C / 15%RH for 2 hours
Step 7: Salt Spray @ 35°C / 95%RH for 30 minutes
Step 8: Freezing @ -20°C for 20 minutes
Transition times:
From step 1 to step 2 = 30 minutes
From step 2 to step 3 = 20 minutes
From step 3 to step 4 = 20 minutes
From step 4 to step 5 = 50 minutes
From Step 5 to step 6 = 50 minutes
From Step 6 to step 7 = 20 minutes
From Step 7 to step 8 = 60 minutes
From Step 8 to step 1 = 20 minutes
The entire cycle is 24 hours and repeatable
Hyundai/Kia CCT-C
An accelerated corrosion test under complex environment shall be performed in accordance with CCT-C of MS600-66
Step 1: Salt Dipping (Immersion) @ 40°C for 4 hours
Step 2: Drying @ 70°C / 30%RH for 2 hours
Step 3: Wetting @ 50°C / 95%RH for 2 hours
Step 4: Natural Drying @ 25°C / 60%RH for 1.5 hours
Step 5: Freezing @ -20°C for 2.5 hours
Transition times:
From step 1 to step 2 = 30 minutes
From step 2 to step 3 = 20 minutes
From step 3 to step 4 = 20 minutes
From step 4 to step 5 = 60 minutes
From Step 5 to step 1 = 20 minutes
The entire cycle is 12 hours and repeatable
Mazda MES MN 601G Test Method for Paint Film
Section 27 for this test standard discusses the 5 class requirements for corrosion testing
Class 1 – Salt Spray Test
Class 2 – Perforation Corrosion Resistance Test
Class 3 – Scratch Corrosion Resistance Test
Class 4 – Edge Corrosion Resistance Test
Class 5 – Filiform Corrosion Resistance Test
Class 2 OR Class 3 can be tested to MAZDA MCT-2M which requires a fully enclosed chamber to perform the following test steps:
- 6 hour Salt Spray @ 35°C in accordance with JIS Z 2371
- 3 hours Drying @ 50°C / 20-40%RH
- 14 Hour wetting @ 50°C / 95% RH
- 1 hour standard ambient temperature
The test profile runs for 24 hours
For Class 2 testing this should be ran for 120 cycles
For Class 3 testing this should be ran for 60 cycles
This test can be ran in an Ascott Cyclic Chamber fitted with some accessories
Nissan Engineering Standard – Composite Corrosion Test
NES M-0007 is used to measure the degree of rusting, blistering and adhesion when the specimen is exposed to corrosive conditions such as salt spray, drying and wetting (condensate humidity)
Method B of the standard requires a Cyclic corrosion chamber which can automatically cycle between periods of salt spray, drying and wetting.
Any one of the following cycles below can be chosen to run this test in agreement with the parties concerned
- CCT-1 -Salt Spray (35°C, 4h) → drying (60°C, 2h)→ wetting (50°C, 95% RH, 2h)
- CCT-2- Salt Spray (35°C, 2h) → drying (60°C, 2h)→ wetting (50°C, 95% RH, 4h)
- CCT-4 -Salt Spray (35°C, 10min) → drying (60°C, 155min)→ wetting (60°C, 95% RH, 75min), with a sub-programme of drying (60°C, 160min)→wetting (60°C, 95%RH, 80min) repeated 5 times
See above hyperlinks for further information on each of these test methods
Nissan NES M0158 – Methods of Compound Corrosion Test
This Nissan engineering standard specifies the method to measure compound corrosion that uses the combined processes of salt spraying or salt solution immersion followed by drying and moistening. The process will simulate and accelerate corrosion of metal materials used on automobiles. Therefore this test will measure corrosion of metals of functional decorative parts together with the coating effect of inorganic or organic plating of vehicle models.
It is an accelerated laboratory corrosion test method that can be used to determine the corrosion resistance of automotive assemblies and components. It is cyclic in nature, i.e.; test specimens are exposed to changing climates over time.
As a rule, the testing equipment shall have the ability to generate and automatically repeat 3 different processes, i.e. salt solution spraying or immersion, drying and moistening.
- CCT-I Corrosion resistance in general (surface rust and penetrated rust): Vehicle body panel, road wheel, under-floor piping, drive shaft, propeller shaft, fastening parts (bolts and nuts) etc.
- CCT-IV External panel scab rust: External panel, external topcoat
- CCT-V Internally accelerated penetration of rust: Internal panel, box structure parts
See the hyperlinks above for information on each individual test standard
Nissan NES M0158 – CCT 5 (CCT-V)
This Nissan engineering standard specifies the method to measure compound corrosion that uses the combined processes of salt spraying or salt solution immersion followed by drying and moistening. The process will simulate and accelerate corrosion of metal materials used on automobiles. Therefore this test will measure corrosion of metals of functional decorative parts together with the coating effect of inorganic or organic plating of vehicle models.
It is an accelerated laboratory corrosion test method that can be used to determine the corrosion resistance of automotive assemblies and components. It is cyclic in nature, i.e.; test specimens are exposed to changing climates over time.
Test specimens are placed in an enclosed chamber and exposed to a changing climate that comprises of a relatively short period of salt immersion, followed by exposure to hot/humid and hot/dry atmospheres. 1 entire test cycle takes 2 hours to execute. The number of entire cycle repeats and therefore the test duration is variable.
The main test cycle begins with 5 minutes salt water immersion at 60°C followed by 55 minutes of drying at 80°C , Humidity less than 30%rh . The final step is wetting at 60°C / 95%RH for 1 hour.
The total cycle is 2 hours and repeatable
The atmosphere in the chamber must be “instant setting” with a transition time of less than 10 seconds, and 1 cycle should take 2 hours. However, the process of Drying → Moistening should take less than 30 minutes.
Mazda MES MN 601G Test Method for Paint Film
Section 27 for this test standard discusses the 5 class requirements for corrosion testing
Class 1 – Salt Spray Test
Class 2 – Perforation Corrosion Resistance Test
Class 3 – Scratch Corrosion Resistance Test
Class 4 – Edge Corrosion Resistance Test
Class 5 – Filiform Corrosion Resistance Test
Class 3-4 are commonly referred to as MAZDA MCT-3M which requires a fully enclosed chamber to perform the following test steps:
- 1 hour Salt Spray @ 35°C in accordance with JIS Z 2371
- 6 hours Drying @ 60°C / 10-30%RH
- 1 Hour wetting @ 50°C / 95% RH
The test profile runs for 8 hours and 180 cycles
This test can be ran in an Ascott Cyclic Chamber fitted with accessories ACC42 & ACC47
Component Corrosion Test
This test procedure is used to evaluate the corrosion performance of coatings applied to components. It is designed to simulate the corrosive conditions of the Arizona Proving Ground (APG) Vehicle Accelerated Corrosion Test (CETP 00.00-R-311). The test requires an Automated Cyclic Corrosion Test Chamber with forced air circulation, temperature control of +/- 2°C to 65°C and relative humidity control of +/- 2% up to 90%.
Ascotts Atmosfar chamber range is the ideal solution for this test , see here for further information – Ascott Atmosfar Chambers
For further information visit the manufacturers website : https://www.ford.com
