Intergranular Corrosion (Weld Decay)
Engineering definition, metallurgical mechanisms, standard testing specifications, and manufacturing guidelines for closed-die forgings up to 50 kg.
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Localized corrosion attack along the grain boundaries of an austenitic stainless steel resulting from chromium depletion caused by chromium carbide precipitation.
Technical Explanation & Metallurgical Principles
When unstabilized austenitic stainless steels (like standard SS 304 or 316) dwell between 450°C and 850°C, carbon migrates to grain boundaries and binds with chromium, forming Cr23C6 carbides. This starves the adjacent matrix of chromium below the 12% threshold required for passivation, causing rapid knife-line corrosion along grain boundaries.
Key Engineering Specifications & Parameters
| Technical Parameter / Metric | Engineering Benchmark / Value |
|---|---|
| Sensitization Range | 450°C to 850°C (840°F to 1560°F) |
| Testing Standard | ASTM A262 Practice E (copper sulfate-sulfuric acid test) |
| Countermeasure | Use 'L' grades (C ≤0.030%) or stabilized grades (321 with Ti, 347 with Nb) |
Application at Jayesh Forge (Rajkot Plant)
Every stainless forging at Jayesh Forge is either solution-quenched or forged from certified 304L/316L/321 alloys with verified ASTM A262 Practice E compliance.
Related Materials, Standards & Products
Related Metallurgical & Testing Terms
Solution Annealing (Solution Treatment)
Heating austenitic or duplex stainless steel above 1040°C to dissolve all chromium carbides, followed by rapid water quenching to trap elements in solid solution.
Austenite (Gamma-Iron Phase)
The face-centered cubic (FCC) solid solution of carbon in gamma-iron, stable in unalloyed steels between 912°C and 1394°C, and stabilized at room temperature in 300-series stainless steels.
ASTM A182 Forged Alloy & Stainless Fittings Standard
Standard specification for forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves for high-temperature service.
Questions Regarding Intergranular Corrosion (Weld Decay)
Titanium has a much higher chemical affinity for carbon than chromium does; it precipitates TiC, leaving Chromium intact to maintain the protective passive film.
Request a Forging Quote with Intergranular Corrosion (Weld Decay) Compliance
Our Rajkot metallurgy desk is ready to review your technical drawings, testing protocols, and delivery schedules for custom closed-die forgings strictly up to 50 kg.