Titanium, aluminum-lithium and nickel superalloy parts, made to print

Three alloy families, three different reasons to use them

Titanium alloys are chosen for strength-to-weight and corrosion resistance, aluminum-lithium alloys for lower density and higher stiffness than conventional aerospace aluminum, and nickel superalloys for strength at temperatures up to about 650 °C and beyond. The table lists the grades and specifications we quote most often.

Titanium alloys

Ti-6Al-4V is the workhorse aerospace titanium alloy, bought as sheet and plate to AMS 4911 or as bar and forgings to AMS 4928 in the annealed condition. It is used where steel is too heavy and aluminum too weak or too hot, from airframe fittings and brackets to engine impellers running at up to about 300 °C. Its low thermal conductivity keeps cutting heat in the tool rather than the chip, so part quality depends on rigid fixturing, sharp tooling and coolant delivery more than on raw spindle power.

Aluminum-lithium alloys

Each 1 wt% of lithium added to aluminum lowers density by about 3% and raises elastic modulus by about 6%, which is why third-generation Al-Cu-Li alloys such as 2050, 2099, 2195 and 2198 replace 2xxx and 7xxx alloys in weight-critical structure. Alloy 2050 was developed to match or exceed 7050-T7451 in tensile and fracture properties with about 4% lower density and up to 5% higher modulus, and 2195 replaced 2219 in launch-vehicle tank structure for large weight savings. Al-Li machines much like other aerospace aluminum; the practical differences are distortion control on thin-walled parts and keeping Al-Li chips separate so the scrap stream stays recyclable.

Nickel-based superalloys

Inconel 718 keeps its structural strength to about 650 °C, above which its γ″ strengthening phase gives way to δ phase, and it is one of the most widely used superalloys in turbine engines, rocket engines and high-temperature fasteners. Inconel 625 is not age-hardenable but resists oxidation and corrosion from cryogenic temperatures to about 980 °C. Both work-harden severely, so tool life, not cycle time, sets the cost. For 718 the heat-treat condition is a quoting decision: solution-treated material (AMS 5662) machines faster but moves slightly when aged afterwards, while solution-treated-and-aged material (AMS 5663) holds its dimensions but wears tools faster. We agree the condition and the sequence before the quote is issued.

DFARS specialty metals and melt source

Under DFARS 252.225-7009, titanium and titanium alloys, and nickel alloys with more than 10% alloying metals, are "specialty metals" that must be melted or produced in the United States or a qualifying country when they are delivered in US defense contracts. The qualifying-country list in DFARS 225.003 includes Japan, Germany, the United Kingdom, France, Israel and 23 other countries; Taiwan is not on it. Aluminum-lithium alloys are not specialty metals under this clause, and electronic components, including PCBs, are excepted.

For that reason Tecsply separates where metal is melted from where it is machined. For defense programs that carry DFARS 252.225-7009, titanium and nickel-alloy material is bought from mills in the United States or a qualifying country, and the mill certificate showing the melt location travels with every lot; machining can then be performed by a qualified partner. For all defense and aerospace work, raw material is not melted in North Korea, China, Russia or Iran, as set out in our covered-nation sourcing commitment. The clause has exceptions, including a 2% de minimis threshold by weight and treatment of commercial off-the-shelf items, which are confirmed with the customer program by program.

Custom manufacturing, built around your print

Tecsply makes every titanium, aluminum-lithium and superalloy part to one customer's drawing and material specification, from a single prototype to recurring production lots, and keeps the same material source, process sequence and inspection plan from the first part to the last. What that means in practice:

• Engineering review before the quote. Every drawing is reviewed for material, heat-treat condition, special processes and inspection requirements before a price is issued, and manufacturability questions come back to your engineer, not a salesperson.
• Hard alloys, complex geometry. Thin walls, deep pockets, tight-tolerance bores and bolt patterns in titanium and nickel superalloys are planned around each alloy's behavior: heat at the cutting edge in titanium, work hardening in Inconel, distortion in thin-walled Al-Li.
• Prototype to production, same process. First articles and production lots are made to the same routing, so qualification data from the prototype still applies when volume starts.
• Flexible scheduling. Single orders, scheduled releases against a blanket order, and expedited lots when a program needs parts sooner; when mill allocation is tight, we propose qualified alternates for your approval instead of letting the date slip.
• Revision control. Engineering changes mid-program are logged against the drawing revision, and the parts, certificates and inspection reports in each shipment all reference the same revision.
• One accountable US supplier. A single US point of contact for PCBs and metal parts, delivered DDP with the paperwork your receiving inspection expects.

Quality records

Every Tecsply metal part order ships with 3 records: the mill certificate with heat number and melt location, the heat-treat and special-process certifications where applicable, and dimensional inspection results, with first-article inspection in AS9102 format when the program requires it. Where a program requires NADCAP-accredited special processes such as heat treatment, non-destructive testing or chemical processing, those processes are placed only with NADCAP-accredited sources.

What to send with a request

A metal-part request with 6 items, drawing or 3D model, alloy and specification, heat-treat condition, quantity, special processes and program flow-downs, can be quoted without a call.

• Drawing or 3D model with revision and tolerances.
• Alloy and specification, for example Ti-6Al-4V to AMS 4928 or Inconel 718 to AMS 5662.
• Heat-treat condition at delivery, and whether aging follows machining.
• Quantity and delivery schedule.
• Special processes: heat treatment, NDT, passivation, coatings.
• Program flow-downs: DFARS 252.225-7009, ITAR, AS9102 first article.

Specialty metal parts FAQ

Three questions that come up on almost every titanium, Al-Li or superalloy quote; the full list is on the FAQ page.

References

1. DFARS 252.225-7009, Restriction on Acquisition of Certain Articles Containing Specialty Metals; DFARS 225.003, definition of qualifying country (acquisition.gov).
2. Light Metal Age, "The Evolution of Constellium Al-Li Alloys for Space Launch and Crew Module Applications": 2050 vs 7050-T7451, 2195 vs 2219.
3. Al-Li density and modulus per wt% lithium: third-generation Al-Cu-Li alloy literature (Springer, Metallurgical and Materials Transactions A, "The Evolution of Al-Li Base Products for Aerospace and Space Applications").
4. voestalpine Specialty Metals, Alloy 718 (AMS 5662 and 5663); Special Metals, INCONEL alloy 625 technical bulletin; Inconel 718 service-temperature limit (γ″ → δ).
5. Carpenter Technology and distributor data sheets for Ti-6Al-4V (AMS 4911, AMS 4928).
6. Machining-induced work hardening of Inconel 718 (Materials, 2022, PMC8780571).
7. NASA Glenn Research Center, CC3 centrifugal compressor: 15 full and 15 splitter blades, 50° backsweep, 210 / 431 mm inlet tip / exit diameter (NTRS 20170002701); impeller image rendered from these parameters.
8. Five-axis flank milling of titanium and nickel-alloy jet-engine impellers with ruled blade surfaces (ResearchGate, "Virtual Five-Axis Flank Milling of Jet Engine Impellers").