17-4PH H900 vs H1025: what buyers choose

The short answer

For CNC **17-4PH**, buyers usually choose between **H900** (higher strength, less toughness) and **H1025** (more balanced strength/toughness). Put the age condition on the PDF before you treat a [quote-new.php](https://3dwk.com/quote-new.php) band as actionable—**rates.v1.1** planning often adds ~+$60/lot for H900/H1025 heat treat when selected (estimate, not an invoice).

This guide is for buyers picking post-machine age condition. Illustrations use an **Example part** only. It is distinct from tolerance callouts covered in [tolerances CNC 17-4PH](https://3dwk.com/resources/tolerances-cnc-17-4ph-what-buyers-specify).

H900 vs H1025 in plain buyer language

**H900:** precipitation hardened near peak strength; common when yield/tensile targets dominate and geometry can tolerate the harder, less ductile condition.

**H1025:** aged at higher temperature; typically lower peak strength than H900 but improved toughness and stress relief behavior for many housings and shafts.

Neither label replaces a print note. “17-4 stainless, heat treat” without H-condition forces clarification or **needs_manual**. Related: [stainless 304 vs 316 vs 17-4PH](https://3dwk.com/resources/stainless-304-vs-316-vs-17-4ph), [heat treating steel after CNC](https://3dwk.com/resources/heat-treating-steel-after-cnc-machining), [CNC cost drivers](https://3dwk.com/resources/cnc-machining-cost-drivers-buyer-guide).

Sequence: machine annealed then age—or buy aged bar?

Many lots machine in solution-treated / annealed condition then age; some features need grind or skim after age for critical fits. State the sequence. If you buy already-aged bar, say so—machinability and time coefficients change. **rates.v1.1** CNC machine-time coefficient for 17-4PH is about ×1.4 versus baseline soft aluminum planning (estimate). Bar stock planning ~$9/kg under the same estimate table—not a PO line.

Illustration 1 compares H900 vs H1025 buyer forks for an **Example part** shaft/housing.

Distortion, stock, and finish interactions

Age can move thin walls and long shafts. Leave stock on critical bores if your process needs post-age finish. Passivation usually follows final machining—see [passivation vs electropolishing](https://3dwk.com/resources/passivation-vs-electropolishing-stainless). Do not call Type III anodize on 17-4PH; wrong finish families waste RFQ cycles.

Tolerances still belong on the print

H-condition choice does not excuse blanket ±0.01 mm. Default ISO 2768-m (or equivalent) and tighten mates only. Bearing registers and sealing flats deserve explicit callouts after the age sequence is clear. See [GD&T basics](https://3dwk.com/resources/gdt-basics-for-buyers) and the 17-4PH tolerances article linked above.

When the quote path goes needs_manual

Incomplete condition notes, mixed H900 features with H1025 notes on one print, or hot lines that also stack deep EDM-like pockets often leave automatic bands. Lot heat-treat adders are modest versus spindle time on complex parts, but ambiguity is expensive. Lines that also exceed configured USD thresholds for hard alloys auto-route to **needs_manual** under **rates.v1.1** rules.

Illustration 2 shows thin RFQ wording versus a quote-ready H-condition block and the resulting estimate path.

Packaging the RFQ

• Alloy: 17-4PH (or UNS S17400) + desired H-condition
• Sequence: machine then age / age then finish criticals
• Qty and whether heat treat is per lot or per piece narrative
• Passivation or other finish after final machine
• Datums and mate tolerances only where needed

Upload on [quote-new.php](https://3dwk.com/quote-new.php) with STEP + PDF. Related process pages: [CNC machining](https://3dwk.com/cnc-machining-service.php), [materials](https://3dwk.com/materials.php).

Example part walkthrough

**Example part:** 17-4PH clevis, ~70×40×20 mm, ISO 2768-m, one Ø12 H7 bore after age, H1025 chosen for toughness, passivate after final machine. Expect a clearer planning band than “17-4, hard, tight.” Same part marked H900 with every wall ±0.01 and no sequence note often widens the band or flips manual—without inventing customer certs.

What buyers usually choose (and why)

• **Fixtures, wear, peak strength targets:** H900 appears more often
• **Structural housings, impact, some shafting:** H1025 appears more often
• **Unknown:** pick one for the prototype lot; do not leave “H900 or H1025 TBD” on a production RFQ

Confirm mechanical targets with your design owner; this page does not replace material specs.

What to do next

Lock H-condition and sequence, then request a range on [quote-new.php](https://3dwk.com/quote-new.php). Treat **rates.v1.1** figures—including ~+$60/lot heat-treat planning—as estimates. If needs_manual appears, answer condition questions before chasing a fake firm mid.

Certification language without over-claiming

If you need material certs or heat-treat charts with the shipment, say so in notes. Do not paste fake cert numbers into the RFQ. **Example part** planning never invents mill certs. Ask for “material cert + heat-treat report if aged” when that is a real requirement—inspectors price paperwork time into manual ranges when the automatic band cannot see it.

Comparing to other stainless choices

If H900/H1025 complexity is not earning its keep, revisit whether 304/316 CNC is enough for corrosion-only prototypes. Switching alloys mid-RFQ means a new parse—do not reuse a 17-4PH mid for 316. For additive paths on stainless-family geometries, keep SLM versus CNC as parallel lines rather than one muddled note.

Lead time expectations

Age cycles and vendor queues add calendar days beyond spindle time. Prototype H1025 lots can still be fast when the shop ages in-house; outsourced age plus passivate stretches need-by windows. Put need-by on the RFQ so lead-time notes stay honest relative to [CNC lead time buyer guide](https://3dwk.com/resources/cnc-machining-lead-time-buyer-guide).

Common questions