Selection summary
Overview
347 uses niobium stabilization to control chromium-carbide precipitation during welding and thermal exposure. It is commonly evaluated for pressure, refinery, power-generation, and aerospace components where high-temperature service matters more than the extra chloride resistance of molybdenum-bearing grades.
This page separates standard-oriented limits from typical reference data. Purchase acceptance comes from the ordered specification and certified material test report.
Names and systems
Identity & standards
Similar designations across ASTM, EN, JIS, and other systems are not automatically interchangeable. Product form and ordered standard control chemistry, properties, dimensions, condition, and testing.
Reference chemistry
Composition
| Element | Reference range | Why it matters |
|---|---|---|
| Carbon | ≤ 0.08% | Controlled for corrosion behavior |
| Chromium | 17.0–19.0% | Oxidation and corrosion resistance |
| Nickel | 9.0–13.0% | Austenitic structure |
| Niobium + tantalum | Stabilized to carbon | Carbide stabilization |
Concise grade-family reference only. Confirm every element limit against the current standard for the exact product ordered.
Condition matters
Reference properties
Annealed flat product; verify ordered standard
Annealed flat product; verify ordered standard
Typical room-temperature reference
Environment first
Corrosion behavior
Designed to resist intergranular attack associated with sensitizing thermal exposure.
Localized chloride resistance is not equivalent to 316L.
Temperature, concentration, deposits, crevices, stress, surface finish, cleaning, and fabrication quality can change service performance.
Service limits
Temperature & service
Confirm stabilization, creep properties, heat treatment, and allowable stress with the governing code.
Delivery condition
Heat treatment & condition
347 is normally solution annealed and rapidly cooled; niobium stabilization controls carbon during relevant welding and elevated-temperature exposure.
A separately ordered stabilization treatment may be needed for severe intergranular-corrosion or high-temperature service; it is not interchangeable with generic stress relief.
Process route
Fabrication
Welding procedures and filler selection should follow the governing construction code.
Machining behavior resembles other work-hardening austenitic grades.
Magnetic response: Normally low magnetic response when annealed.
Decision boundaries
Comparisons & substitution
Compared with 321, 347 uses niobium stabilization and is commonly available as matching filler for welding titanium-stabilized 321.
Compared with 304L, 347 is considered when stabilized-grade behavior or high-temperature code data matters more than the low-carbon route.
Where it is used
Applications
Ordering scope
Product forms & standards
Plate, sheet, and strip under the applicable flat-product specification and ordered finish.
Bar, rod, shapes, and forgings under the product-specific stainless standard.
Seamless or welded pipe and tube under the ordered dimensional, service, and testing specification.
Decision support
Selection guidance
Choose this grade when
- Niobium stabilization is specified for welded elevated-temperature service.
- Pressure-equipment practice already recognizes the grade.
Review another grade when
- Chloride pitting controls material selection.
- The specified product form or code favors 321 or a low-carbon grade.
Before ordering
Procurement checklist
Name the governing product standard, edition, dimensions, tolerances, edge, finish, and delivery condition.
Require the exact UNS designation and a material test report; a familiar trade name alone is not an acceptance criterion.
Confirm corrosion environment, design temperature, fabrication route, inspection, certification, marking, and packaging before order release.
Traceable evidence