19 ADVANCED MATERIALS & PROCESSES | APRIL 2021 - - ranging from 6.0 from ranging [5] . [4] Ti-64 billets, with nominal compo nominal with billets, Ti-64 sition per AMS 4935 with an elongated grain structure that that structure grain with an elongated stretch hot by recrystallized is often - resul The and annealing. straightening of recrystallized consists structure tant alpha, with colony grains prior beta combination an excellent which offers - and fa toughness, fracture of strength, tigue life MATERIA S AND ROCESSIN AND MATERIA S to 9.25 in. in diameter, were induction induction were diameter, in 9.25 in. to the beta above a temperature to heated distinct two into and extruded transus shapes two These profiles. geometric their uniqueness in for selected were of geometryapplication and terms is often (Fig. 2). While the “T profile” compo structural aerospace used for complex the shape with more nents, Forward extrusion process where process extrusion Fig. 1 — Forward the through metal pushes the hot the ram die. ------. In [2] - extrud . A beta [3] or higher -1 The metal extrusion process can can process extrusion The metal be broadly classified into two main two classified into be broadly and indirect categories—direct ed titanium billet will yield products products yield will billet titanium ed tion of the extruded part. To relate the relate To part. tion of the extruded of that to of the workpiece section cross - common a value product, the extruded estab was ratio the extrusion ly called of lished, which is defined as the ratio sec cross original billet of the the area product of the extruded that tion (Ao) to or reduction (Af). ratio, The extrusion De as (Ao/Af). be expressed can ratio, a wide geometry, pending on final part - extrud for ratios of extrusion range - is avail products titanium ing different extrusion titanium most able. Typically, systems hydraulic water are presses in the rates high strain with remarkably of 10 s range the process described here, the direct the direct described here, the process - em was process extrusion or forward on are the die and ram where ployed, in travels ends and the billet opposite (Fig. 1). as the ram the same direction of the work section the cross Typically, sec than the cross is much larger billet META E TR SION META truded at PES and provides the me and provides PES truded at microstructures, properties, chanical consis and dimensional tolerances the length of full the throughout tent extrusion. presents different near net shapes ex net near different presents
- - . The [1]
In an effort to further reduce over reduce further to an effort In xtruded shapes are often ideal for for ideal often shapes are xtruded re that components long aircraft quire consistent cross sections sections cross consistent quire AEROS ACE A ICATIONS AEROS ACE B. Campbell Gudipati* and Michael Phani P. Kentucky Shapes, Hopkinsville, Plymouth Engineered NET SHA E E TR SION OR OR SHA E E TR SION NET in making industry aerospace progress recent could benefit from The the beyond applications for titanium extrusions net shape near components of an aircraft. long structural AD ANCEMENTS IN NEAR NEAR IN AD ANCEMENTS throughout the length of the part throughout most common aerospace extrusions in- extrusions aerospace common most using the produced tracks clude seat Ti-6Al-4V alloy, titanium workhorse major advancements (Ti-64). However, in the use of extruded occurred have in a variety shapes deployed titanium from range Uses applications. other of in subsonic systems parts specialized - in unmanned subma components to of titanium’s advantage take rines that relation- strength-to-density favorable resistance. ship and superior corrosion extru- the in used temperatures Billet typi- shapes are alloy sion of titanium - tempera transus beta the above cally and the reduction of the material, ture - oth in used those higher than are ratios - extru titanium types. Gross er product savings in radical sion, while producing - closer shape approxi due to materials less machining to also requires mation, achieve the finished product. and improve costs all manufacturing division R&D the ratio, buy-to-fly the Shapes (PES) of Plymouth Engineered - developed an innova has successfully near and manufactured process tive net shape Ti-64 extrusions, roughly 30 ft roughly shape Ti-64 extrusions, net in- that scale long, on a production This article geometries. cludes various International *Member of ASM E 2 ADVANCED MATERIALS & PROCESSES | APRIL 2021 packed for shipment. Fig. 3—Titanium billets are extruded inthebeta fieldusingrequired dies,thermallystraightened, surface alphacase chemically removed, and near net titanium shapes. Fig. 2—Geometric profiles oftwoselected RES TS AND DISC SSION illustrated inFig.3. sequence ofoperations isschematically the thinlayer ofsurface alphacase. The sions are chemically treated to remove hance machinability, finishedextru- the full length of the extrusion. To en- ness (bow/camber), andtwist along across thewidthofpart, straight and key characteristics suchasflatness to themechanical achieve properties nealing, inaccordance withAMS4935, jected to hot straightening andan- billet size. up to 40ftlong,dependingoninitial although typical extrusions can be for aplanned30ftofextruded length, are designedfor athicknessof0.150in. profile to beextruded. Theseprofiles on billet size, extrusion ratio, andthe trusion process are selected based ified tool steel. Parameters for theex and manufactured in-housewithmod- for theextrusion process are designed in aeroengine applications. Diesused geometric features isutilized (NNS-3) profiles were successfully extruded to Extruded products are then sub Dimensions. Thetwo selected - - - um extrusions requires extreme control nominal. of thetotal permissiblelimitfrom the by presenting avariation lessthan50% have outperformed thespecification feature, Plymouth’s near net extrusions for adeviation of±0.060in.onagiven are beta extruded to over30ftlong. and complex geometrical profile (bottom) Ti-64. Asamplecutfrom theT-profile (top) Fig. 4—Near net extrusions produced in Figs. 6 and 7. While AMS 2245 mensions for both profiles are shown in and variation to nominalplanneddi- Results ofdimensionalmeasurements testing andmicrostructural evaluation. ples for room temperature mechanical each profile andthelocation ofsam- the different dimensionsmeasured for ing thefinishedproduct. Figure 5shows extrusions playamajorrole inmachin- mal variation) andstraightness ofthe bility (uniform dimensionswithmini- over 30ftlong(Fig.4).Dimensionalsta- Straightness. Machiningoftitani- [6] allows Fig. 5.Room temperature mechanical tained from thelocation indicated in testing andmicrostructure were ob structure. Specimensfor mechanical for machining. making themexceptionally favorable limits thanspecifiedinAMS2245,thus here alsooffer muchtighter tolerance but thenear net extrusions described not onlywell withinallowable limits, age values ofcritical characteristics are table. that Itcan theaver beobserved of theextrusion are alsoshown in the overand twist thefulllength observed in Table ofbow 1.Themaximumlevel of the near net extrusions are presented tolerances onthenorthandsouthends constraints, onlythetransverse flatness ly machinethefinalpart. Dueto space paramount importance to successful- es alongthelengthofextrusion isof shape profiles, holdingthesetoleranc duction intheenvelope dueto near net full lengthoftheextruded part. Withre ness, twist, andangularityalongthe such astransverse flatness, straight of tolerances onkey characteristics microstructure are excised. and samplesfor mechanical testing and profiles where dimensionswere measured Fig. 5—Location onthetwoextruded Mechanical Properties &Micro------21 ADVANCED MATERIALS & PROCESSES | APRIL 2021 - - - , was found to be 100 µm. to found , was [8] It must be stated that the original that be stated It must Each preform process process Each preform Buy-To-Fly. Optical micrographs from the near from micrographs Fig. 8 — Optical and (top) T-profile shape extrusions: net alpha along colony indicate NNS-3 (bottom) Samples were grains. beta the recrystallized polishing. after reagent with Kroll’s etched ment of near net shape extrusions, the shape extrusions, net ment of near thus is further reduced, ratio buy-to-fly with associated the costs decreasing machining. was a T-profile for extrusion standard pre its over an improvement already 3 presents Table (plate). vious preform ratio. buy-to-fly the in reduction further Longitudinal and transverse surface surface and transverse Longitudinal using a measured also was roughness in a resulted that profilometer standard profiles. both for of 80-130 Ra range stock plate and casting, forging, as such loss of material a considerable incurs the excessive to during machining due the fin- around built envelope material considerably Extrusions ished product. and provide ratio the buy-to-fly reduce alternative by offered not advantages With the develop processes. preform geometric profiles. In addition, optical optical In addition, profiles. geometric a microstructure present micrographs Ti-64, processed beta from resulting - recrystal alpha along the with colony (Fig. 8). Av boundaries grain beta lized to according measured size, grain erage E112 ASTM - 0.3 0.7
Max. twist, deg. 0.055 0.010 2, As observedmicroscope. in Table in full are results testing mechanical re with the strength compliance both for of AMS 4935 quirements South 0.008 South 0.000 , and optical microscopy microscopy , and optical [7] NNS-3 North 0.000 T-profile North 0.013 Product typeProduct Location Flatness, in. in. Max. bow, NEAR NET EXTRUSIONS NET NEAR TABLE 1 — AVERAGE TOLERANCES ON KEY CHARACTERISTICS OF CHARACTERISTICS KEY ON TOLERANCES AVERAGE — 1 TABLE Deviation from the nominal planned dimensions on NNS-3. Note that the near net the near that the nominal planned dimensions on NNS-3.Fig. 7 — Deviation from Note along the full length of dimensions with minimal variation consistent exhibits profile extruded per AMS 2245. permissible limits much less than the the extrusion, Deviation from the nominal planned dimensions on the T-profile. Note that the near that Note the nominal planned dimensions on the T-profile. Fig. 6 — Deviation from along the full length dimensions with minimal variation consistent exhibits profile extruded net per AMS 2245. much less than the permissible limits of the extrusion, - longitudi the in samples on testing according performed was nal direction E8 ASTM to was performed using a Keyence digital digital using a Keyence performed was 22 ADVANCED MATERIALS & PROCESSES | APRIL 2021 product forms. Fig. 9—Comparisonto produce ofweight/ft thefinished part for both profiles from various NEAR NET E TRU E PRO UCTS TABLE ROOM TEMPERATURE MECHANICAL PROPERTIES OF SUMMARY tosion technology create theseshapes. the advantages ofusingnear net extru- for each product type, clearly exhibiting method. Figure 9 shows the weight/ft savings over thecurrent manufacturing veloped by PEScan provide significant plate, thenear net extrusion method de iscurrently beingmachinedfromNNS-3 Although most finishedproduct for TABLE BUY-TO-FLY RATIOS FOR T O GEOMETRIC PROFILES stream machiningandfinishing in asingleoperation, andlessdown - to extrude complex shapesover length er parts count resulting from theability tooling costs and material usage, low- the buy-to-fly ratio includereduction in rdc yeY,kiUS s L RA,% EL,% UTS,ksi YS, ksi Product type Economic advantages ofreducing Plymouth extrusion Standard extrusion AMS 4935 T-profile Product type Finished parts NNS-3 Plate 3. 147.0 146.0 132.0 130.0 2. 130.0 120.0 [9] . PES - T-Profile 13.47 1.00 1.64 4.26 an aircraft. ~AM&P the beyond long structural members of using thisnovel concept inapplications duction ofnear net shapeextrusions by technological advancements inthepro could significantly benefitfrom these thatbelieve theaerospace industry merits of titanium alloys, the authors net shapeextrusions. Consideringthe and AMS2245,respectively, for thenear ness are inaccordance withAMS4935 such astransverse flatness andstraight and extrusion-critical characteristics temperature mechanical properties, production scale. Microstructure, room facturing near net shape extrusions ona to reduce thebuy-to-fly ratio by manu- has successfully techniques developed 6031.0 38.0 20.0 16.0 19.0 10.0
NNS-3 8.66 1.00 1.32 - - - 201 Commerce Ct., Hopkinsville, 9. ing Average Grain Size, ASTM E112–13. 8. E8M –16a. Testing ofMetallic Materials, ASTM E8/ 7. Revised June2003. AMS 2245Rev. B,issuedDec.1973, Alloy Extruded Bars, Rods andShapes, 6. 1959-06, Revised 2017-09. Processed, AMS4935Rev. L,issued Welded RingsTi-6Al-4VAnnealedBeta 5. nology. Briefs inAppliedSciences andTech- 4. 2013. 3. sion Processes, Mechanical Metallurgy. 2. March 1989. Henderson, neering, PlymouthEngineered pati, director of innovation and engi- For more information: Phani P. Gudi- 1. References plymouth.com. 42240, 270.839.2064,pgudipati@
Tit R. W G. G.E. Die D. Sander St St T R.R. Bo olerances, Titanium andTitanium andard Test Method for Determin- andard Test Method for Tension Legate, Titanium 2013, Las Vegas, anium Alloy ExtrusionsandFlash anhill andS.Barter, Springer Journal ofMaterials, p36-39, yer, E.R.Barta, andJ.W. ter, Classification ofExtru- s, et al.,ITA, Atlanta, 2012. Shapes, KY, KY,