Grade dossier
17-7 PH Stainless Steel for Formed High-Strength Parts
A semi-austenitic precipitation-hardening grade supplied in formable conditions and transformed before aging to achieve high strength in sheet, strip, wire and springs.
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 | 0.090 max |
|---|---|
| Mn | 1.00 max |
| Si | 1.00 max |
| P | 0.040 max |
| S | 0.040 max |
| Cr | 16.00-18.00 |
| Ni | 6.00-7.75 |
| Al | 0.75-1.50 |
Properties with context
Minimums, typical indicators and delivered condition
Specified annealed flat-product values
| Condition A | Austenitic/formable starting condition |
|---|---|
| TH1050 | Thermally transformed then aged |
| RH950 | Subzero transformed then aged |
| CH900 | Cold-worked then aged; route-sensitive |
Selection indicators
| Density | about 7.8 g/cm3 |
|---|---|
| Transformation | Conditioning or cold work precedes aging |
| Corrosion position | Generally similar to 304 in many mild environments |
| Procurement rule | Specify complete condition sequence |
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 17-7 PH 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
Springs, diaphragms and bellows
High-strength clips and formed sheet parts
Aircraft and industrial strip components
Wire products after route qualification
Reasons to stop and review
Treating an annealed part as fully hardened
Mixing TH, RH and CH property values
Welding after final aging without requalification
Ignoring dimensional change during transformation and aging
Fabrication route
Protect properties through cutting, forming and welding
Form in the condition selected for the route.
Document conditioning, refrigeration/cold work and aging sequence.
Qualify welding before the final transformation cycle.
Inspect final hardness, distortion and mechanical properties.
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.
Sheet and strip to ASTM A693
Bar and shapes under applicable ASTM specifications
Wire and spring products
Formed diaphragms, bellows and clips
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 17-7 PH against the controlling question
Procurement FAQ
Questions to close before placing the order
Is 17-7 PH stainless steel magnetic?
Magnetic response depends on microstructure and delivered condition.
Can 17-7 PH 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?
No. TH1050, RH950 and CH900 are different processing routes. A complete condition sequence is part of the material specification.
What should a 17-7 PH 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 A693 requirements for UNS S17700 sheet and strip
Carpenter Technology Custom 631 (17Cr-7Ni) official datasheet
Applicable ASTM/AMS wire and bar specification
Qualified heat-treatment procedure and final-condition test plan