Corrosion Evaluation For Failure Analysis 

Corrosion evaluation gives manufacturers a repeatable way to explain why a metal surface, plating, or coating changed after exposure. It connects visible damage to measurements that support a clear disposition decision. 

Summary of Corrosion Evaluation Testing

When a return arrives with rust staining, pitting, or coating lift, a corrosion failure analysis effort should start with controlled documentation, not opinions. The lab photographs the part as received, records orientation, and notes packaging because abrasion, trapped moisture, and residue transfer can alter evidence. Next, the lab maps affected zones and prioritizes where to section or test so results trace back to real conditions.

Teams often route the work through a qualified corrosion test lab to keep chamber records and reporting consistent across lots and suppliers. If the work needs broader analytical support, the Reliable Analysis team can align the corrosion plan to the larger failure analysis question. 

When To Use Corrosion Evaluation 

Use corrosion evaluation when parts corrode during storage, shipment, outdoor service, or washdown, since each environment drives different wetting and contamination patterns. It also fits when a supplier changes a finish, pretreatment, or packaging step and the next lot shows premature corrosion failure that does not match historical performance. 

Teams commonly pair documentation and sectioning with controlled exposure, then compare progression to the original damage map to confirm the pathway. Many programs start with ASTM B117 salt spray testing or salt fog testing for screening, then move to cyclic or customer methods when the field environment requires it. When moisture cycling drives the issue, teams often add humidity testing to separate humidity driven changes from salt driven attack. 

Common triggers include: 

• A spike in returns after a coating or plating change 
• Corrosion concentrated at seams, fasteners, or edges after shipment 
• Cosmetic and functional concerns that require a defendable test record 

Start simple when the evidence is clear and the damage pattern points to one exposure pathway. Expand the plan when the damage mode stays ambiguous or when the team needs chamber data to validate the mechanism. 

The Importance Of Corrosion Evaluation 

First off, corrosion progresses through pathways that can hide under a coating or inside a joint. A structured plan starts by mapping where attack begins, then it links that location to an exposure pathway such as trapped electrolyte, chloride deposition, or contact between dissimilar metals. This approach reduces debate because each hypothesis must match the morphology and chemistry found on the part. 

Second, a strong program also prevents repeat failures by focusing on mechanism instead of symptoms. A testing laboratory such as Reliable Analysis can run an early corrosion damage assessment to separate coating related attack from base metal loss, then decide whether to expand into accelerated exposure that reproduces the pattern. Corrosion mechanism identification becomes more credible when sectioning, deposit chemistry, and exposure progression all point to the same pathway. Once the pathway is clear, teams can set pass/fail criteria that match function and service environment rather than relying on appearance alone. 

Common risks reduced by testing 

Edge defects, seams, and fastener interfaces often create electrolyte traps that accelerate local attack. Ranking these locations early shortens the time to a useful conclusion. 

How Test Data Supports Pass/Fail Decisions and Compliance 

A pass/fail decision needs measurable end points, such as creep from a scribe, pit depth, blister density, mass change, or adhesion loss. This data also supports corrosion corrective action support because it shows whether a change shifted performance under controlled exposure, not just whether a part looked better once. 

Scope Of Corrosion Testing Programs 

A corrosion evaluation project starts with intake control that preserves as received evidence before handling can change the surface. The lab photographs parts, records orientation, and documents packaging because abrasion, trapped moisture, and residue transfer can mimic real in service damage. For returns, the lab builds a comparison set using retained samples or unused controls from the same lot to keep field return corrosion analysis defensible. Next, corrosion lab testing shifts to sectioning and targeted measurements guided by the damage map, including polished cross sections that show how attack moves through coating layers or along interfaces. 

When deposit chemistry matters, teams pair the cross sections with SEM and EDS so corrosion root cause analysis can link observations to controllable inputs such as surface preparation, coating thickness, or contamination control. 

Pretesting preparation and sample evaluation 

The lab reviews drawings and finish callouts, then selects fixtures that avoid artificial crevices. A corrosion risk assessment for components often sets the first test locations. 

Data Analysis and Result Validation 

The lab logs solution chemistry, temperature, pH, and inspection intervals for every condition so results remain repeatable. It verifies chamber setpoints with calibrated probes and records any adjustments during the run. It also documents both typical and worst case outcomes, which strengthens supplier comparisons and supports corrosion failure analysis conclusions. 

For return populations, field return corrosion analysis stays aligned to the original damage map, which strengthens corrosion mechanism identification. 

Documentation and Reporting Requirements 

Reports should list methods, durations, acceptance criteria, and photo evidence that shows progression. A complete report enables corrosion corrective action support by stating what the data supports and what it rules out. Teams often request corrosion investigation services when that clarity needs to move quickly across functions. 

Common Testing Standards For Corrosion Evaluations 

• ASTM B117 salt fog supports repeatable screening and trending across coatings and process changes, and it aligns with ASTM B 117 salt spray testing. 
• ASTM B368 CASS accelerates attack for certain plated and decorative finishes when faster differentiation matters. 
• SAE J2334 uses cyclic conditions that better represent road environments where wetting and drying drives corrosion growth. 
• GMW3286 and GMW14872 support automotive corrosion programs that must match General Motors requirements. 
• ISO 9277 can support consistent terminology and evaluation approaches, and it aligns with ISO 9277 corrosion testing. 

Some projects add EIA 364 26 salt spray testing or MIL-STD-883 salt atmosphere testing for electrical components. 

Frequently Asked Questions Pertaining to Corrosion Evaluations 

How does a lab start corrosion investigation services on a single failed part?

First, the lab photographs the part, records orientation and packaging condition, and protects residues before any cleaning or handling changes the surface. Next, the team selects at least one control and marks initial inspection and section locations to support mechanism confirmation. 

What should be included in a corrosion lab testing request?

A complete request includes drawings, finish callouts, coating or plating specifications, and a clear description of the service, storage, and shipment environment. Add cleaning steps, packaging materials, recent process changes, and acceptance criteria so the lab can choose end points and exposure duration. 

When should a team add corrosion damage assessment before chamber work?

When staining, coating lift, and base metal attack overlap, teams should add corrosion damage assessment before exposure work begins. Cross sections and targeted inspections separate underfilm growth from surface discoloration so the chamber plan matches the actual damage pathway. 

How does corrosion root cause analysis support a supplier discussion?

Corrosion root cause analysis ties the failure to a controllable input such as thickness variation, surface preparation, or process chemistry using measurable evidence. Clear comparisons between suspect and baseline parts then keep the supplier discussion focused on verified differences. 

What does an investigation service usually deliver beyond photos?

Beyond photos, an investigation service delivers a mechanism based explanation with supporting records and test details that hold up in internal reviews and supplier meetings. A focused retest plan and inspection intervals can also confirm whether corrective actions reduced risk. 

Expert Laboratory Testing For Corrosion Evaluation 

Applus+ Reliable Analysis supports corrosion evaluation with disciplined documentation, controlled exposure, and mechanism focused interpretation that fits failure analysis decision making. Teams use our laboratory testing services to build a baseline, then verify improvements with retesting that supports corrective action verification.  

Additionally, we provide comprehensive reports shortly after completion of the testing, and we stay in constant communication throughout the test process. 

Ready to get started? Request a quote to begin your corrosion evaluation so you can confirm the root cause and next steps.