Grade dossier
317 Stainless Steel for Higher-Molybdenum Corrosion Service
A higher-molybdenum austenitic grade offering more localized-corrosion margin than 316 in selected environments, with carbon level and product standard kept explicit.
Identity before substitution
Define the grade, product and condition together
A familiar grade name is not a complete purchase specification. Product form, controlling standard, dimensions, condition, finish, certification and service environment determine whether the delivered material is suitable.
Composition control
ASTM A240/A240M flat-product chemistry
Limits are not heat analysis targets
The table summarizes grade limits commonly used for plate, sheet and strip. Pipe, tube, bar, forgings and cast products can be governed by different specifications. Always place the product standard and edition on the purchase order.
| C | 0.08 max |
|---|---|
| Mn | 2.00 max |
| Si | 0.75 max |
| P | 0.045 max |
| S | 0.030 max |
| Cr | 18.00-20.00 |
| Ni | 11.00-15.00 |
| Mo | 3.00-4.00 |
| N | 0.10 max |
Properties with context
Minimums, typical indicators and delivered condition
Specified annealed flat-product values
| Tensile strength | 515 MPa min |
|---|---|
| 0.2% yield strength | 205 MPa min |
| Elongation | 35% min |
| Hardness | 95 HRBW max |
Selection indicators
| Density | about 8.0 g/cm3 |
|---|---|
| Corrosion position | Higher molybdenum than 316 |
| Magnetic response | Normally low annealed; can increase after cold work |
| Heat treatment | Not hardened by thermal treatment |
Values depend on product form, thickness, test orientation, condition and governing edition. Use the mill test certificate and the purchase specification for acceptance, not a web table alone.
Selection boundary
Where 317 belongs and where to escalate
Grade selection is an environmental decision, not a popularity contest. Review the complete medium, temperature, geometry, fabrication, cleaning and inspection requirements.
Good reasons to evaluate it
Chemical and pulp-processing equipment after media review
Higher-molybdenum tanks and transfer components
Parts requiring UNS S31700 chemistry
Applications where 316 lacks margin but 317 is validated
Reasons to stop and review
Assuming 317 is immune to warm chlorides
Substituting 317L without weld and carbon review
Using generic corrosion charts instead of process data
Ordering without product form or governing specification
Fabrication route
Protect properties through cutting, forming and welding
Use exposure-specific corrosion data or tests.
Qualify filler and heat input for the intended service.
Protect surfaces from iron contamination and heat tint.
State carbon limit, finish and test requirements on the RFQ.
Supply definition
Product form changes the applicable requirements
Do not send an RFQ that names only the grade. State form, governing standard, dimensions, tolerances, finish, edge or end condition, quantity, certification and inspection.
Plate, sheet and strip under ASTM A240/A240M
Bar and shapes under applicable long-product standards
Pipe and tube under product-specific specifications
Fabricated chemical-process equipment
Certificate checkpoint
Request heat identity, chemical analysis, mechanical results and compliance to the exact product specification. Add PMI, corrosion testing or supplementary examination only when the application requires it.
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Interactive selection check
Test 317 against the controlling question
Procurement FAQ
Questions to close before placing the order
Is 317 stainless steel magnetic?
Magnetic response depends on microstructure and delivered condition.
Can 317 replace another grade?
Only after checking the governing standard, composition, mechanical properties, corrosion exposure, fabrication route and certification. A commercial name is not a substitution approval.
Does the table apply to every product form?
Not automatically. The values shown use flat-product requirements as a reference. Other forms can use different product standards, dimensions and tests.
What should a 317 RFQ include?
Product form, standard and edition, UNS or EN designation, dimensions, tolerances, finish, quantity, service, fabrication, certificate and inspection requirements.
Sources, scope and RFQ
Use traceable grade data, then specify the actual product
ASTM A240/A240M requirements for UNS S31700 flat product
ASTM A959 harmonized wrought-grade composition
Producer corrosion-selection guidance for higher-molybdenum austenitic grades
Applicable product-form specification and project corrosion data