General corrosion
Define every chemical species, concentration, temperature, aeration, flow and expected corrosion allowance.
Technical guide
Stainless Steel Corrosion Resistance Chart
Corrosion resistance is a system result, not a permanent grade score. Chemistry, temperature, deposits, crevices, stress, fabrication and cleaning can change performance.
First questionExact medium and concentration
Localized riskChlorides, crevices and deposits
Final decisionService evidence plus design review
Decision summary
Classify the corrosion mechanism before comparing grades
Uniform corrosion, pitting, crevice corrosion, stress-corrosion cracking and galvanic effects require different data and controls.
Pitting and crevice corrosion
Chlorides, temperature, deposits, gasket geometry and stagnant zones can dominate selection.
Stress-corrosion cracking
Tensile stress, chloride exposure and temperature interact; fabrication residual stress matters.
Galvanic corrosion
Identify connected metals, area ratio, electrolyte and electrical continuity.
Intergranular risk
Confirm grade, carbon control, heat treatment, welding and any required corrosion test.
Microbiologically influenced corrosion
Review water source, nutrients, stagnation, biofilm, cleaning and operating history.
Reference table
Qualitative corrosion screening chart
This matrix indicates grade families to review first. It is not a guarantee and does not replace chemical-specific data, testing or a corrosion specialist.
| Environment | 304L starting review | 316L starting review | Duplex / higher-alloy review | Data still required |
|---|---|---|---|---|
| Dry indoor atmosphere | Often reviewed | Often reviewed | Usually selected for another duty | Humidity, contaminants, cleaning |
| Outdoor industrial atmosphere | Case-specific | Often reviewed | Consider for severe exposure or strength | Salt deposition, pollution, drainage |
| Fresh water | Case-specific | Often reviewed | Consider for warmer or contaminated water | Chloride, temperature, oxygen, stagnation |
| Chloride splash or coastal | Elevated localized-corrosion risk | Case-specific | Duplex or higher alloy may be reviewed | Chloride, wet-dry cycle, crevices, finish |
| Seawater contact | Specialist review | Specialist review | Higher-alloy duplex, super-austenitic or nickel alloy may be required | Temperature, flow, biology, crevices, cathodic protection |
| Acid or process chemical | Chemical-specific review | Chemical-specific review | Special alloy review may be required | Full composition, concentration, temperature, impurities |
Terms such as often reviewed and case-specific are screening language only. A grade can fail in an unfavorable design or contaminated environment.
Working method
Create a defensible corrosion-selection brief
The most useful inquiry describes the whole exposure, component design and acceptable consequence of damage.
Describe the medium completely
List normal, cleaning and upset chemistry, concentration, pH, impurities, gases, solids and biological activity.
Map operating conditions
Provide temperature, pressure, velocity, aeration, stagnation, wet-dry cycles and exposure duration.
Show corrosion-sensitive geometry
Identify crevices, gaskets, deposits, heat-transfer surfaces, welds, dead legs and dissimilar-metal contacts.
Define verification
Specify literature basis, coupon or laboratory testing, corrosion allowance, inspection plan, passivation and documentation.
Limits and escalation
Do not convert a screening chart into a service guarantee
Chloride alone is incomplete
Temperature, oxygen, pH, crevices, deposits and stress change localized-corrosion risk.
Finish and fabrication matter
Heat tint, embedded iron, rough welds and poor drainage can reduce practical performance.
Laboratory tests have limits
Standard tests compare controlled conditions; they do not reproduce every field mechanism or design detail.
Cleaning is part of service
Acids, hypochlorites, disinfectants and rinse quality can be more aggressive than normal operation.
Interactive planning aid
Identify the data needed for a corrosion review
Choose the dominant exposure. The result gives a cautious starting family and the missing service data.
Frequently asked questions
Stainless steel corrosion resistance FAQ
No. 316 often improves localized-corrosion resistance relative to 304, but it can still pit, crevice-corrode or crack in unsuitable chloride, temperature or stress conditions.
No. Duplex grades offer useful strength and chloride resistance, but fabrication, phase balance, temperature range, product availability and the exact environment must be reviewed.
No. Cleaning and passivation can remove contamination and support a clean passive surface, but they cannot replace adequate alloy selection or good design.
Not generally. Accelerated tests are comparative under defined conditions and should not be converted directly into field life without a validated correlation.
Method, sources and review
Traceable sources and review status
Industry overview of stainless corrosion mechanisms and selection factors.
Technical education on general and localized corrosion mechanisms.
Industry guidance connecting grade selection, environment and design details.
Producer technical resources for corrosion-based material screening.
The chart is qualitative screening guidance. Final selection requires current source data, complete service conditions, design and fabrication review, and testing or specialist advice where consequences are significant.
Corrosion service context
Compare corrosion resistance against the actual exposure, not a grade label alone.
A corrosion chart should be read with chloride level, temperature, concentration, crevice conditions, product form and the inspection or maintenance plan.
- Exposure chemistry
- Temperature margin
- Maintenance plan
Visual process context
Make the exposure condition and verification route visible.
Reserve one image for the service environment and another for the material condition, test method or inspection evidence.
Engineering and sourcing support
Request stainless against the actual corrosion environment
Send chemistry, temperature, flow, crevices, stress, cleaning, design life, tests, quantity and destination.