The short answer
On a CNC aerospace RFQ, **7075-T6** and **7075-T73** are not the same quote package. T6 usually means higher strength with more stress-corrosion cracking (SCC) sensitivity in some service environments. T73 trades some strength for improved SCC resistance after a controlled overaging temper. Silence on temper intent is what widens many [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** estimate bands—not the envelope alone.
This guide is for buyers packaging prismatic 7075 RFQs. Illustrations use an **Example part** only—not a customer airframe fitting. Related alloy notes live in [6061 vs 7075 aluminum for machined parts](https://3dwk.com/resources/6061-vs-7075-aluminum-for-machined-parts) and [plate vs billet stock for CNC aluminum](https://3dwk.com/resources/plate-vs-billet-stock-cnc-aluminum); here we focus on **how to label T6 vs T73** so estimators do not guess mill certs you never sent.
What T6 and T73 mean for quoting
T6 is a peak-aged temper commonly stocked for high-strength 7075 machining. T73 is an overaged temper often selected when SCC resistance or dimensional stability after machining matters more than absolute peak strength. For quoting, also say whether the temper must be certified on the finished part, on the blank only, or whether a shop re-temper after roughing is allowed. Process pages for aluminum aerospace parts ([CNC 3-axis Al 7075 aerospace](https://3dwk.com/en/cnc-3axis/al-7075/aerospace.html), [CNC 5-axis Al 7075 aerospace](https://3dwk.com/en/cnc-5axis/al-7075/aerospace.html), [CNC 3-axis Al 7075](https://3dwk.com/en/cnc-3axis/al-7075.html)) assume clear temper notes when lots mix structural and non-structural details.
Do not bury “7075 somehow” inside a materials paragraph. Put **7075-T6** or **7075-T73** on the RFQ and mirror it in the PDF title block. Background: [DFM checklist before an online CNC quote](https://3dwk.com/resources/dfm-checklist-before-online-cnc-quote), [what files to send for a CNC quote](https://3dwk.com/resources/what-files-to-send-for-cnc-quote).
Strength, SCC and stock form
T6 blanks machine well but leave less margin for SCC-sensitive geometries (thin webs, residual tensile stress, aggressive chemical environments). T73 stock may be less common in every gage, which can widen lead bands even when machine minutes look similar. Soft stock analogs (PA66 time coeff ×0.8 under **rates.v1.1** estimates) are not substitutes here—7075 still sits in the aluminum family for time coeffs, but temper availability and cert paperwork drive the band. Hot alloys (IN718/IN625 ×2.5, CoCr ×2.2) are a different story; do not mix their coeffs into a 7075 RFQ. Aggressive “certify finished temper after heavy rough” asks frequently auto-route toward **needs_manual**, especially when the line mid exceeds configured planning bands.
If only a mill cert on the blank is required, say so. If post-machine temper verification is mandatory, expect longer planning.
Bar $/kg planning bands (estimates only): PA66 ~5, 17-4PH ~9, IN718 ~55, IN625 ~60—useful for contrast, not as 7075 invoices. Aluminum plate/billet pricing still dominates 7075 RFQs; name stock form—see [how stock size changes a CNC quote](https://3dwk.com/resources/how-stock-size-changes-cnc-quote).
Finish sequence and residual stress
Type II / Type III anodize, chem film, and shot peen interact with temper choice and residual stress. Mask maps and keep-outs still apply—see [as-machined before Type II anodize](https://3dwk.com/resources/as-machined-before-type-ii-anodize), [chem film vs Type II anodize aluminum](https://3dwk.com/resources/chem-film-vs-type-ii-anodize-aluminum), and [how anodize choice changes CNC RFQ cost](https://3dwk.com/resources/how-anodize-choice-changes-cnc-rfq-cost). Heavy asymmetric roughing on T6 can move datums; call out stress-relief expectations if any.
Tolerance and inspection traps
Tight flatness on thin 7075 webs fights stock temper and machining sequence. Default non-critical sizes to ISO 2768-m and put functional tolerances only on locating or sealing features. Related: [surface roughness Ra for machined parts](https://3dwk.com/resources/surface-roughness-ra-for-machined-parts), [datum schemes for multi-setup CNC parts](https://3dwk.com/resources/datum-schemes-for-multi-setup-cnc-parts), [GD&T basics for buyers](https://3dwk.com/resources/gdt-basics-for-buyers).
Illustration 1 shows an **Example part** with T6 vs T73 callouts and cert scope (blank vs finished).
Example part walkthrough
**Example part:** 7075 plate ~150×90×20 mm aerospace bracket, TEMPER: 7075-T73 preferred for SCC margin, mill cert on blank OK, no post-machine re-temper, ISO 2768-m general, critical hole true position 0.08 to Datum A, chem film on exterior with as-machined seal land. With STEP + clear temper labels, expect a usable automatic planning band on [quote-new.php](https://3dwk.com/quote-new.php). Same geometry with “7075 aerospace somehow” often lands DFM notes or **needs_manual**—without inventing any customer PO or mill lot.
Illustration 2 contrasts a vague RFQ (“7075 high strength”) versus a labeled T6/T73 block and the clearer estimate path.
What widens bands fastest
Unlabeled temper, “T6 or equivalent” without SCC notes, conflicting re-temper after roughing, and 100% hardness mapping of every piece with no sampling plan. Quantity breaks help unit cost but do not erase temper-availability risk—see [how quantity breaks change CNC unit cost](https://3dwk.com/resources/how-quantity-breaks-change-cnc-unit-cost) and [what needs_manual means](https://3dwk.com/resources/what-needs-manual-means-preliminary-quote).
What to do next
Mark **7075-T6** or **7075-T73**, state cert scope (blank vs finished), then upload on [quote-new.php](https://3dwk.com/quote-new.php). Service pages: [CNC machining](https://3dwk.com/cnc-machining-service.php), [materials](https://3dwk.com/materials.php). Treat **rates.v1.1** min/mid/max as estimates, not invoices. If the UI shows **needs_manual**, answer the temper questions rather than forcing a fake firm price.
Common questions
Can I specify “7075” without a temper?
You can, but expect wider **rates.v1.1** bands or **needs_manual**. Estimators cannot invent your SCC vs strength priority.
Is T73 always more expensive than T6?
Not always on machine minutes—stock availability and cert paperwork often dominate. Rare gages of T73 can widen lead and price bands even when cycle time looks similar.
Does anodize replace temper choice?
No. Finish protects surfaces; temper still governs bulk SCC / strength behavior. Keep temper and finish notes separate on the RFQ.
How does this relate to 6061 RFQs?
6061-T6 remains the common general-purpose alternative when 7075 strength is unnecessary—see [6061 vs 7075 aluminum for machined parts](https://3dwk.com/resources/6061-vs-7075-aluminum-for-machined-parts).