{"id":4471,"date":"2026-09-11T08:38:04","date_gmt":"2026-09-11T08:38:04","guid":{"rendered":"https:\/\/hontitan.com\/?p=4471"},"modified":"2026-09-11T08:38:06","modified_gmt":"2026-09-11T08:38:06","slug":"titanium-casting-methods","status":"publish","type":"post","link":"https:\/\/hontitan.com\/fr\/titanium-casting-methods\/","title":{"rendered":"M\u00e9thodes de coul\u00e9e du titane : moulage \u00e0 la cire perdue, moulage en sable et coul\u00e9e sous vide expliqu\u00e9s"},"content":{"rendered":"

La r\u00e9activit\u00e9 extr\u00eame du titane avec l'oxyg\u00e8ne rend le moulage en sable standard impraticable pour la plupart des applications \u2014 le titane fondu s'enflamme \u00e0 l'air libre. La m\u00e9thode dominante est coul\u00e9e \u00e0 la cire perdue sous vide<\/strong>, qui combine un proc\u00e9d\u00e9 de carapace c\u00e9ramique \u00e0 cire perdue avec une chambre sous vide \u00e9tanche et un four \u00e0 creuset froid en cuivre refroidi \u00e0 l'eau. D'autres m\u00e9thodes, notamment le moulage sous vide en coquille et la coul\u00e9e centrifuge, existent dans des cr\u00e9neaux limit\u00e9s. Ce guide d\u00e9taille chaque m\u00e9thode de coul\u00e9e du titane viable, explique l'exigence obligatoire du vide, compare les \u00e9conomies des proc\u00e9d\u00e9s et couvre les \u00e9tapes de post-traitement (HIP, \u00e9limination de la couche alpha\u2011case, traitement thermique) que les acheteurs du secteur a\u00e9rospatial et m\u00e9dical n\u00e9gligent syst\u00e9matiquement lors de l'\u00e9tablissement des budgets.<\/p>\n\n\n\n

Pourquoi la coul\u00e9e du titane est fondamentalement diff\u00e9rente de celle des autres m\u00e9taux<\/h2>\n\n\n\n

La plupart des m\u00e9taux peuvent \u00eatre fondus et coul\u00e9s dans un moule en sable \u00e0 l'air libre. Le titane, non.<\/p>\n\n\n\n

\u00c0 des temp\u00e9ratures sup\u00e9rieures \u00e0 environ 1100 \u00b0C, le titane fondu r\u00e9agit violemment avec l'oxyg\u00e8ne et l'azote. Il dissout les gaz atmosph\u00e9riques dans le bain de fusion, formant une couche de surface fragile enrichie en oxyg\u00e8ne appel\u00e9e cas alpha<\/strong> \u2014 et en cas d'exposition s\u00e9v\u00e8re, le m\u00e9tal peut s'enflammer. Il ne s'agit pas d'un simple inconv\u00e9nient de manipulation. C'est une r\u00e9alit\u00e9 m\u00e9tallurgique qui \u00e9limine des cat\u00e9gories enti\u00e8res de m\u00e9thodes de coul\u00e9e qui fonctionnent parfaitement pour l'acier, l'aluminium ou m\u00eame les superalliages \u00e0 base de nickel.<\/p>\n\n\n\n

La cons\u00e9quence : pratiquement toutes les m\u00e9thodes de coul\u00e9e du titane viables n\u00e9cessitent un environnement sous vide ou sous atmosph\u00e8re inerte contr\u00f4l\u00e9e.<\/strong> Cette seule contrainte modifie tout \u2014 les \u00e9quipements, l'outillage, le temps de cycle, la qualification des fournisseurs et les co\u00fbts.<\/p>\n\n\n\n

Comprendre cela d\u00e8s le d\u00e9part permet d'\u00e9viter des cycles de demandes de devis inutiles aupr\u00e8s de fonderies qui \u201c font de la coul\u00e9e \u201d mais ne disposent pas de l'infrastructure adapt\u00e9e au titane.<\/p>\n\n\n\n

Les quatre principales m\u00e9thodes de coul\u00e9e et leur compatibilit\u00e9 avec le titane<\/h3>\n\n\n\n
\"Titanium<\/figure>\n\n\n\n
M\u00e9thode<\/th>Compatible avec le titane ?<\/th>Pourquoi \/ Pourquoi pas<\/th><\/tr><\/thead>
Coul\u00e9e \u00e0 la cire perdue sous vide<\/strong><\/td>\u2705 Oui \u2014 m\u00e9thode principale<\/td>La chambre sous vide \u00e9tanche et la carapace c\u00e9ramique pr\u00e9viennent la contamination atmosph\u00e9rique<\/td><\/tr>
Moulage sous vide en coquille<\/strong><\/td>\u2705 Oui \u2014 cr\u00e9neau limit\u00e9<\/td>Le moulage sous pression \u00e9lev\u00e9e sous vide est viable ; n\u00e9cessite un \u00e9quipement sp\u00e9cialis\u00e9<\/td><\/tr>
Coul\u00e9e centrifuge<\/strong><\/td>\u2705 Oui \u2014 sp\u00e9cialis\u00e9<\/td>Utilis\u00e9 pour les anneaux et tubes ; environnement sous vide requis<\/td><\/tr>
Moulage en sable<\/strong><\/td>\u26a0\ufe0f Tr\u00e8s limit\u00e9<\/td>Le moulage en sable conventionnel provoque une couche alpha\u2011case s\u00e9v\u00e8re ; le moulage en sable sous vide existe mais est rarement utilis\u00e9 pour le titane<\/td><\/tr>
Coul\u00e9e par gravit\u00e9 en moule permanent<\/strong><\/td>\u274c Non viable<\/td>Le titane fondu r\u00e9agit avec les outillages en acier ou en fonte<\/td><\/tr>
Moulage sous pression standard<\/strong><\/td>\u274c Non viable<\/td>La pression d'injection est incompatible avec la r\u00e9activit\u00e9 du titane ; absence de contr\u00f4le du vide<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Le reste de ce guide se concentre sur les trois m\u00e9thodes viables en usage pratique : la coul\u00e9e \u00e0 la cire perdue sous vide, le moulage sous pression sous vide, et \u2014 le cas \u00e9ch\u00e9ant \u2014 le moulage en sable du titane.<\/p>\n\n\n\n

Coul\u00e9e \u00e0 la cire perdue sous vide : le proc\u00e9d\u00e9 dominant pour le titane<\/h2>\n\n\n\n

La coul\u00e9e \u00e0 la cire perdue sous vide (\u00e9galement appel\u00e9e coul\u00e9e \u00e0 cire perdue sous vide) repr\u00e9sente 85\u201390% des pi\u00e8ces moul\u00e9es en titane \u00e0 usage commercial. C'est la m\u00e9thode que la plupart des fonderies d\u00e9signent lorsqu'elles parlent de \u201c moulage du titane \u201d sans autre pr\u00e9cision.<\/p>\n\n\n\n

Pourquoi ce proc\u00e9d\u00e9 domine-t-il :<\/strong> La capacit\u00e9 quasi-net-shape de la coul\u00e9e \u00e0 la cire perdue minimise l'usinage post-coul\u00e9e d'un mat\u00e9riau co\u00fbteux et difficile \u00e0 usiner. La carapace c\u00e9ramique tol\u00e8re le point de fusion \u00e9lev\u00e9 point de fusion du titane (1668\u00b0C \/ 3034\u00b0F). Et le proc\u00e9d\u00e9 est intrins\u00e8quement \u00e9volutif par lots \u2014 une seule campagne de four sous vide peut couler simultan\u00e9ment des dizaines de pi\u00e8ces.<\/p>\n\n\n\n

Le proc\u00e9d\u00e9 de coul\u00e9e \u00e0 la cire perdue sous vide, \u00e9tape par \u00e9tape<\/h3>\n\n\n\n
\"Vacuum<\/figure>\n\n\n\n

1. Fabrication du mod\u00e8le<\/strong>
Des mod\u00e8les en cire ou en thermoplastique du composant cible sont moul\u00e9s par injection \u00e0 l'aide d'outillages usin\u00e9s avec pr\u00e9cision. Pour les pi\u00e8ces a\u00e9rospatiales de haute pr\u00e9cision tol\u00e9rance, les mod\u00e8les en cire usin\u00e9s par CNC sont de plus en plus courants afin d'\u00e9liminer les variations dimensionnelles li\u00e9es \u00e0 l'outillage d'injection.<\/p>\n\n\n\n

2. Construction de la carapace<\/strong>
Les mod\u00e8les sont tremp\u00e9s \u00e0 plusieurs reprises dans une barbotine c\u00e9ramique et enrob\u00e9s de sable r\u00e9fractaire. Pour le titane en particulier, les carapaces standard \u00e0 base de silice sont inad\u00e9quates \u2014 le titane en fusion r\u00e9duit la silice (SiO\u2082), contaminant ainsi le bain. La norme industrielle utilise zircone stabilis\u00e9e \u00e0 l'yttria (YSZ)<\/strong> ou des couches de parement en zircone stabilis\u00e9e \u00e0 la chaux, qui sont chimiquement inertes vis-\u00e0-vis du titane liquide. Une carapace titane typique n\u00e9cessite 8 \u00e0 12 couches de trempage et atteint une \u00e9paisseur de paroi de 8 \u00e0 12 mm \u00e9paisseur de paroi.<\/p>\n\n\n\n

3. D\u00e9cirage et pr\u00e9chauffage<\/strong>
Les moules en c\u00e9ramique sont chauff\u00e9s pour \u00e9liminer le mod\u00e8le en cire, laissant des cavit\u00e9s c\u00e9ramiques creuses. Les moules sont ensuite pr\u00e9chauff\u00e9s \u00e0 150\u2013300 \u00b0C avant la coul\u00e9e afin d'am\u00e9liorer le remplissage et de r\u00e9duire le choc thermique.<\/p>\n\n\n\n

4. Pr\u00e9paration de l'\u00e9lectrode<\/strong>
Plut\u00f4t que d'utiliser des mati\u00e8res de charge conventionnelles, les fonderies de titane utilisent g\u00e9n\u00e9ralement une \u00e9lectrode consommable<\/strong> \u2014 une barre compact\u00e9e d'alliage de titane qui sert \u00e0 la fois de mati\u00e8re premi\u00e8re et d'anode dans le processus de fusion \u00e0 l'arc. La composition de l'\u00e9lectrode doit correspondre \u00e0 la sp\u00e9cification de l'alliage cible (par ex., AMS 4991 pour les pi\u00e8ces coul\u00e9es en Ti-6Al-4V).<\/p>\n\n\n\n

5. Chargement et mise sous vide de la chambre<\/strong>
La carapace c\u00e9ramique pr\u00e9chauff\u00e9e et l'\u00e9lectrode en titane sont charg\u00e9es dans la chambre de coul\u00e9e. La chambre est herm\u00e9tiquement ferm\u00e9e et mise sous vide pouss\u00e9 \u2014 g\u00e9n\u00e9ralement inf\u00e9rieur \u00e0 10\u207b\u00b3 mbar \u2014 afin d'\u00e9liminer l'oxyg\u00e8ne atmosph\u00e9rique et l'azote avant tout chauffage.<\/p>\n\n\n\n

6. Fusion en creuset froid (proc\u00e9d\u00e9 VAR)<\/strong><\/p>\n\n\n\n

\"Cross-section<\/figure>\n\n\n\n

Il s'agit de l'\u00e9tape qui distingue le plus le titane des autres m\u00e9taux coul\u00e9s par moulage \u00e0 la cire perdue. Un creuset en cuivre refroidi \u00e0 l'eau (skull melter)<\/strong> est utilis\u00e9 plut\u00f4t qu'un creuset c\u00e9ramique conventionnel, car le titane en fusion r\u00e9agit avec les c\u00e9ramiques oxydes. Un arc \u00e9lectrique est amorc\u00e9 entre l'\u00e9lectrode consommable et une petite quantit\u00e9 de mat\u00e9riau de d\u00e9marrage dans le creuset. Le titane fond \u00e0 partir de l'extr\u00e9mit\u00e9 de l'\u00e9lectrode et s'accumule dans le bol en cuivre refroidi \u00e0 l'eau.<\/p>\n\n\n\n

The outer layer of the titanium pool solidifies against the copper walls \u2014 forming the \u201cskull\u201d \u2014 while the interior remains liquid. This skull of solid titanium physically prevents contact between the molten pool and the copper. Temperatures in the melt pool exceed 1700\u00b0C.<\/p>\n\n\n\n

7. Tilt Pour or Centrifugal Pour<\/strong>
Once the required melt volume is achieved, the chamber tilts (or a centrifuge mechanism engages) to pour molten titanium into the preheated shell. The entire pour happens within the sealed vacuum environment. Centrifugal casting variants spin the shell at 200\u2013500 RPM during pouring to improve fill of thin sections.<\/p>\n\n\n\n

8. Controlled Cooling and Shell Removal<\/strong>
Castings cool in the vacuum or inert atmosphere before the chamber is opened. Ceramic shell is removed by mechanical knockout, vibratory decladding, or high-pressure water blasting.<\/p>\n\n\n\n

9. Cutoff and Initial Inspection<\/strong>
Gates and risers are removed. Initial dimensional inspection and visual inspection follow. For aerospace applications, first-article inspection typically includes coordinate measuring machine (CMM) dimensional verification.<\/p>\n\n\n\n

What Tolerances Can You Expect?<\/h3>\n\n\n\n

Titanium investment castings typically achieve:<\/p>\n\n\n\n

    \n
  • Linear dimensional tol\u00e9rance:\u00a0\u00b10.005 in\/in (\u00b10.13 mm\/mm)<\/strong>\u00a0per ASTM B372 \/ industry practice<\/li>\n\n\n\n
  • Surface finish:\u00a0Ra 1.6\u20133.2 \u00b5m (63\u2013125 \u00b5in) as-cast<\/strong>\u00a0\u2014 significantly better than sand casting<\/li>\n\n\n\n
  • Minimum \u00e9paisseur de paroi:\u00a01.5\u20132mm<\/strong>\u00a0for most alloys<\/li>\n<\/ul>\n\n\n\n

    These tolerances assume proper tooling design and shell quality. Complex internal passages, cores, or thin sections require design-for-manufacturing review.<\/p>\n\n\n\n

    Titanium Sand Casting: When It Works and When It Doesn\u2019t<\/h2>\n\n\n\n

    Sand casting is the world\u2019s most common metal casting process \u2014 but titanium makes it far more complicated than casting iron or steel.<\/p>\n\n\n\n

    The fundamental problem: conventional silica sand contains SiO\u2082 (silicon dioxide). At titanium casting temperatures, molten titanium aggressively reduces SiO\u2082, pulling oxygen into the melt and depositing silicon contamination. The result is a brittle, oxygen-enriched alpha-case layer on the casting surface that can extend several millimeters deep, requires aggressive chemical milling to remove, and represents a structural liability in load-bearing applications.<\/p>\n\n\n\n

    This is why the common statement \u201csand casting can be used for titanium\u201d is technically true but practically misleading for most engineering applications.<\/strong><\/p>\n\n\n\n

    Where Titanium Sand Casting Is Actually Used<\/h3>\n\n\n\n

    Titanium sand casting does exist \u2014 but it uses non-reactive refractory aggregates<\/strong>, not conventional silica sand. Viable mold materials include:<\/p>\n\n\n\n

      \n
    • Graphite molds<\/strong>\u00a0(most common for larger titanium parts)<\/li>\n\n\n\n
    • CaO-stabilized zirconia aggregate<\/strong><\/li>\n\n\n\n
    • Calcia (CaO) or yttria (Y\u2082O\u2083) face-coat sand molds<\/strong><\/li>\n<\/ul>\n\n\n\n

      And the entire process still requires a vacuum or inert-atmosphere environment<\/strong> for melting and pouring. Open-air titanium sand casting is not viable at production quality.<\/p>\n\n\n\n

      In practice, titanium \u201csand casting\u201d (usually graphite mold casting) is used for:<\/p>\n\n\n\n

        \n
      • Large structural aerospace parts<\/strong>\u00a0(wing carry-through structures, fuselage frames) where the geometry is too large for standard investment casting equipment<\/li>\n\n\n\n
      • Parts up to 500 kg where investment casting tooling costs are prohibitive<\/li>\n\n\n\n
      • Low-volume or prototype parts where shell tooling isn\u2019t justified<\/li>\n<\/ul>\n\n\n\n

        Trade-offs vs. investment casting:<\/strong><\/p>\n\n\n\n

        Param\u00e8tres<\/th>Coul\u00e9e \u00e0 la cire perdue sous vide<\/th>Vacuum Sand\/Graphite Casting<\/th><\/tr><\/thead>
        Surface finish (as-cast)<\/td>Ra 1.6\u20133.2 \u00b5m<\/td>Ra 6.3\u201312.5 \u00b5m (rougher)<\/td><\/tr>
        Dimensional tol\u00e9rance<\/td>\u00b10.005 in\/in<\/td>\u00b10.010\u20130.015 in\/in<\/td><\/tr>
        Max part size<\/td>~25\u201350 kg (typical equipment)<\/td>500+ kg feasible<\/td><\/tr>
        Co\u00fbt de l'outillage<\/td>Moderate (wax\/ceramic tooling)<\/td>Lower (graphite machining)<\/td><\/tr>
        Alpha-case depth<\/td>0.1\u20130.3 mm (ceramic shell)<\/td>0.3\u20130.8 mm (graphite mold)<\/td><\/tr>
        Applications typiques<\/td>Aerospace brackets, medical implants, industrial valves<\/td>Airframe structures, large pump casings<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

        The key takeaway: for any precision or structural titanium casting under ~50 kg, vacuum investment casting delivers better dimensional control and surface finish at comparable cost.<\/strong> Graphite mold casting becomes the practical choice when part size exceeds standard investment casting furnace capacity.<\/p>\n\n\n\n

        Vacuum Die Casting for Titanium: The High-Pressure Alternative<\/h2>\n\n\n\n

        Vacuum die casting of titanium occupies a narrow but real niche, primarily studied and commercialized in the 1990s\u20132000s as a route to lower-cost titanium components. Research at ORNL and other institutions demonstrated that vacuum die casting can produce near-net-shape titanium parts with wall thicknesses down to 1mm at cycle times much faster than investment casting.<\/p>\n\n\n\n

        How it differs from conventional die casting:<\/strong><\/p>\n\n\n\n

          \n
        • The die cavity is evacuated before injection<\/li>\n\n\n\n
        • Tooling must be compatible with titanium\u2019s reactivity (specialized die coatings or materials)<\/li>\n\n\n\n
        • Shot speeds and pressures are modified to prevent turbulence that entraps gas<\/li>\n<\/ul>\n\n\n\n

          The catch:<\/strong> titanium\u2019s high point de fusion (1668\u00b0C) and reactivity with most tool steels makes die longevity a persistent challenge. Standard H13 tool steel dies used for aluminum die casting are not suitable \u2014 titanium solders to them and erodes them rapidly. This has limited widespread commercial adoption.<\/p>\n\n\n\n

          Where vacuum die casting for titanium currently sees use:<\/p>\n\n\n\n

            \n
          • High-volume consumer\/automotive Ti components where investment casting tooling amortization is slow<\/li>\n\n\n\n
          • Thin-wall structural shapes that investment casting struggles to fill consistently<\/li>\n<\/ul>\n\n\n\n

            For most aerospace and medical procurement engineers, vacuum investment casting remains the default and the safe choice.<\/p>\n\n\n\n

            Post-Processing: The Part of Titanium Casting That Surprises Buyers<\/h2>\n\n\n\n

            One of the most common budget surprises in titanium procurement: the casting itself is only part of the cost. Aerospace and medical applications require additional processing steps that add 30\u201370% to the part cost.<\/p>\n\n\n\n

            Pressage isostatique \u00e0 chaud (HIP)<\/strong><\/p>\n\n\n\n

            Titanium investment castings contain micro-porosity from gas entrapment and solidification shrinkage. For structural applications, this porosity must be eliminated. HIP subjects the casting to simultaneous high temperature (~900\u2013950\u00b0C) and high isostatic pressure (100\u2013175 MPa \/ ~15,000\u201325,000 PSI) in an inert argon atmosphere. This collapses internal voids without changing external dimensions.<\/p>\n\n\n\n

            HIP is mandatory for flight-critical aerospace castings<\/strong> and for load-bearing medical implants. It is not optional if your part specification calls out AMS 2175 (castings standard) or AMS 2801 (heat treatment). Budget approximately 15\u201325% cost addition for HIP.<\/p>\n\n\n\n

            Alpha-Case Removal<\/strong><\/p>\n\n\n\n

            Even with a good vacuum, the outermost surface of titanium castings develops a brittle, oxygen-enriched alpha-case layer. For investment castings with yttria-stabilized zirconia shells, this layer is typically 0.05\u20130.2 mm thick. For graphite mold castings, it can reach 0.5\u20131.0 mm.<\/p>\n\n\n\n

            Alpha case must be removed before the part is used in structural applications. Methods:<\/p>\n\n\n\n

              \n
            • Chemical milling (acid etching)<\/strong>: Most common; HF\/HNO\u2083 solutions dissolve the surface layer uniformly<\/li>\n\n\n\n
            • Mechanical removal<\/strong>: Electrochemical machining (ECM) or controlled abrasive blasting in some configurations<\/li>\n<\/ul>\n\n\n\n

              NADCAP-certified processing is standard for aerospace applications.<\/p>\n\n\n\n

              Traitement thermique<\/strong><\/p>\n\n\n\n

              Ti-6Al-4V and other alpha-beta alloys typically receive a stress relief anneal or full solution treat + age cycle after casting to achieve target mechanical properties. Required parameters are alloy-specific and specified in AMS 2801 or the customer\u2019s engineering specification.<\/p>\n\n\n\n

              NDT Requirements<\/strong><\/p>\n\n\n\n

              Aerospace castings commonly require:<\/p>\n\n\n\n

                \n
              • X-ray or CT scanning (ASTM E1742 \/ MIL-STD-453)<\/li>\n\n\n\n
              • Fluorescent penetrant inspection (FPI per ASTM E1417)<\/li>\n\n\n\n
              • Chemical analysis (per-heat traceability to AMS or ASTM spec)<\/li>\n<\/ul>\n\n\n\n

                These add cost but are non-negotiable for flight hardware. Medical implants add biocompatibility certification requirements (ISO 10993, ASTM F136 for implant-grade Ti-6Al-4V TR\u00c8S FAIBLE TENEUR INTERSTITIELLE).<\/p>\n\n\n\n

                Selecting the Right Titanium Casting Method: A Decision Framework<\/h2>\n\n\n\n

                The right casting method depends on four variables: part size, required tol\u00e9rance, production volume, and application criticality.<\/p>\n\n\n\n

                Facteur de d\u00e9cision<\/th>Coul\u00e9e \u00e0 la cire perdue sous vide<\/th>Graphite\/Sand Mold Casting<\/th>Moulage sous vide en coquille<\/th><\/tr><\/thead>
                Part weight<\/td><25\u201350 kg<\/td>Up to 500+ kg<\/td><5 kg (typical)<\/td><\/tr>
                Tol\u00e9rance requirement<\/td>Tight (\u00b10.005 in\/in)<\/td>Moderate (\u00b10.010\u20130.015)<\/td>Tight (\u00b10.003\u20130.005)<\/td><\/tr>
                Surface finish priority<\/td>Haut<\/td>Low-moderate<\/td>Haut<\/td><\/tr>
                Volume<\/td>Low to medium<\/td>Faible<\/td>Medium to high<\/td><\/tr>
                Geometric complexity<\/td>High \u2014 thin walls, internal passages<\/td>Low-moderate<\/td>Moderate \u2014 thin walls<\/td><\/tr>
                Aerospace\/medical certifiable<\/td>Yes \u2014 industry standard<\/td>Yes \u2014 for large structures<\/td>Limited \u2014 less established<\/td><\/tr>
                Relative tooling cost<\/td>Mod\u00e9r\u00e9<\/td>Faible<\/td>High (die cost)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

                Practical selection rules:<\/strong><\/p>\n\n\n\n

                  \n
                • Part under 25 kg + complex geometry + aerospace\/medical =\u00a0coul\u00e9e \u00e0 la cire perdue sous vide<\/strong><\/li>\n\n\n\n
                • Part over 100 kg + simpler geometry + cost-sensitive =\u00a0vacuum graphite mold casting<\/strong><\/li>\n\n\n\n
                • High-volume + thin wall + consumer\/automotive =\u00a0vacuum die casting<\/strong>\u00a0(if supplier is qualified)<\/li>\n\n\n\n
                • \u201cCan we sand cast this titanium bracket?\u201d from a conventional foundry =\u00a0non<\/strong>\u00a0\u2014 redirect to vacuum investment casting<\/li>\n<\/ul>\n\n\n\n

                  Titanium Casting Grades: Which Alloy to Specify<\/h2>\n\n\n\n

                  Three titanium grades represent approximately 95% of castings in production:<\/p>\n\n\n\n

                  CP Titanium Grade 2 (Commercially Pure)<\/strong><\/p>\n\n\n\n

                    \n
                  • Density: 4.51 g\/cm\u00b3; R\u00e9sistance \u00e0 la traction: ~345 MPa as-cast<\/li>\n\n\n\n
                  • Standards: ASTM B367, ASME SB367, ASTM F67 (for medical)<\/li>\n\n\n\n
                  • Best for: Maximum r\u00e9sistance \u00e0 la corrosion applications \u2014 chemical process equipment, marine hardware, non-structural medical housings<\/li>\n\n\n\n
                  • Don\u2019t use for: Any load-bearing structural application<\/li>\n<\/ul>\n\n\n\n

                    Ti-6Al-4V (Grade 5 \/ AMS 4991)<\/strong><\/p>\n\n\n\n

                      \n
                    • Density: 4.43 g\/cm\u00b3; R\u00e9sistance \u00e0 la traction: 895\u2013930 MPa (as-cast, post-HIP)<\/li>\n\n\n\n
                    • Standards: AMS 4991 (casting), ASTM F136 (implant-grade TR\u00c8S FAIBLE TENEUR INTERSTITIELLE variant)<\/li>\n\n\n\n
                    • Best for: Aerospace brackets, engine mounts, orthopedic implants, racing components<\/li>\n\n\n\n
                    • Note: \u201cTi-6Al-4V\u201d and \u201cASTM F136\u201d are not interchangeable \u2014 medical implants require the TR\u00c8S FAIBLE TENEUR INTERSTITIELLE (Extra Low Interstitial) variant with tighter oxygen\/nitrogen\/hydrogen limits<\/li>\n<\/ul>\n\n\n\n

                      Ti-6Al-2Sn-4Zr-2Mo (Grade 6 \/ AMS 4999)<\/strong><\/p>\n\n\n\n

                        \n
                      • Density: 4.54 g\/cm\u00b3; significantly higher fluage resistance than Gr 5<\/li>\n\n\n\n
                      • Standards: AMS 4999<\/li>\n\n\n\n
                      • Best for: Jet engine stators, high-temperature actuators, components with sustained loads above 315\u00b0C (600\u00b0F)<\/li>\n\n\n\n
                      • Cost: 2\u20133\u00d7 Ti-6Al-4V; only justified when operating temperature demands it<\/li>\n<\/ul>\n\n\n\n

                        Real Cost Ranges for Titanium Castings<\/h2>\n\n\n\n

                        Cost transparency is rare in titanium casting. Based on supplier data and industry benchmarks:<\/p>\n\n\n\n

                        Component Type<\/th>Alliage<\/th>Rough Cost Range<\/th>Key Cost Driver<\/th><\/tr><\/thead>
                        Simple valve body (50\u2013200g)<\/td>CP Gr 2<\/td>$800\u2013$1,500\/unit<\/td>Small volume, vacuum overhead<\/td><\/tr>
                        Aerospace bracket (0.5\u20132 kg)<\/td>Ti-6Al-4V<\/td>$1,800\u2013$3,500\/unit<\/td>HIP + X-ray + cert requirements<\/td><\/tr>
                        Medical hip stem (0.3\u20130.8 kg)<\/td>Ti-6Al-4V ELI<\/td>$4,000\u2013$7,500\/unit<\/td>ASTM F136 cert + electropolishing<\/td><\/tr>
                        Large structural frame (10\u201325 kg)<\/td>Ti-6Al-4V<\/td>$8,000\u2013$25,000\/unit<\/td>Furnace cycle cost, post-processing<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

                        Raw material cost for Ti-6Al-4V is approximately $80\u2013$120\/kg for casting-grade sponge\/electrode. But material is typically only 25\u201340% of total part cost \u2014 vacuum processing overhead, specialty ceramics, HIP, NDT, and certification compliance dominate.<\/p>\n\n\n\n

                        The rule of thumb: titanium castings cost 5\u201310\u00d7 equivalent stainless steel castings and 15\u201320\u00d7 equivalent aluminum castings.<\/strong> This premium is justified when the application demands the strength-to-weight ratio, r\u00e9sistance \u00e0 la corrosion, or biocompatibility that titanium uniquely provides.<\/p>\n\n\n\n

                        Qualifying a Titanium Casting Supplier: What to Ask<\/h2>\n\n\n\n

                        Most foundries cannot produce titanium castings. The equipment investment \u2014 vacuum arc melting furnaces, copper skull melters, yttria shell systems \u2014 runs $2\u20135M+, and the process expertise takes years to develop. Before sending an RFQ, verify:<\/p>\n\n\n\n

                        Equipment:<\/strong><\/p>\n\n\n\n

                          \n
                        • Does the foundry have its own vacuum arc remelting (VAR) or skull melting equipment? (Not outsourced)<\/li>\n\n\n\n
                        • What is the maximum furnace capacity (kg per heat)?<\/li>\n\n\n\n
                        • Is HIP done in-house or at a NADCAP-certified subcontractor?<\/li>\n<\/ul>\n\n\n\n

                          Certifications :<\/strong><\/p>\n\n\n\n

                            \n
                          • AS9100 Rev D (aerospace quality management) for aerospace parts<\/li>\n\n\n\n
                          • NADCAP accreditation in casting (AC7102) and applicable special processes<\/li>\n\n\n\n
                          • ISO 13485 for medical device applications<\/li>\n\n\n\n
                          • Per-heat material traceability to AMS 4991 or ASTM F136<\/li>\n<\/ul>\n\n\n\n

                            Process Controls:<\/strong><\/p>\n\n\n\n

                              \n
                            • What ceramic shell system do they use? (Answer should reference yttria or calcia face coats \u2014 not generic silica)<\/li>\n\n\n\n
                            • What vacuum level is achieved before pour? (Should be sub-10\u207b\u00b3 mbar)<\/li>\n\n\n\n
                            • What is their documented scrap rate for titanium? (Expect 10\u201320% for complex parts; significantly higher is a red flag)<\/li>\n<\/ul>\n\n\n\n

                              Red flags:<\/strong> \u201cWe occasionally do titanium\u201d \/ no dedicated vacuum furnace \/ generic material certs not tied to heat numbers.<\/p>\n\n\n\n

                              Questions fr\u00e9quemment pos\u00e9es<\/h2>\n\n\n\n

                              Can titanium be sand cast?<\/strong>
                              Titanium can be cast in graphite or calcia\/yttria-stabilized sand molds, but conventional silica sand reacts with molten titanium and is not suitable. Any titanium sand or graphite mold casting still requires a vacuum or inert-atmosphere environment for the melt and pour. For most precision applications under 50 kg, vacuum investment casting offers better results.<\/p>\n\n\n\n

                              Why does titanium casting require a vacuum?<\/strong>
                              Molten titanium reacts aggressively with oxygen and nitrogen at its casting temperature (above 1668\u00b0C). These reactions form brittle interstitial phases and an alpha-case surface layer that compromises mechanical properties. A vacuum environment prevents atmospheric exposure during melting and pouring.<\/p>\n\n\n\n

                              What is alpha case in titanium casting?<\/strong>
                              Alpha case is a brittle, oxygen-enriched surface layer that forms when molten titanium contacts oxygen or nitrogen. It is harder than the bulk material and has significantly reduced ductilit\u00e9 and fatigue life. For structural applications, alpha case must be removed by chemical milling (acid etching) before part acceptance.<\/p>\n\n\n\n

                              What is HIP and why is it required for titanium castings?<\/strong>
                              Hot Isostatic Pressing (HIP) uses simultaneous heat (~900\u00b0C) and high inert gas pressure (~175 MPa) to collapse internal micro-porosity in the casting. For aerospace and load-bearing medical applications, the internal integrity HIP provides is a specification requirement, not a supplier option.<\/p>\n\n\n\n

                              Is Ti-6Al-4V the best alloy for titanium castings?<\/strong>
                              For most applications, yes. Ti-6Al-4V (AMS 4991) offers the best combination of strength, castability, and available certification data. CP Gr 2 is preferred when maximum r\u00e9sistance \u00e0 la corrosion matters more than strength. Ti-6Al-2Sn-4Zr-2Mo (AMS 4999) is only justified for high-temperature applications above ~315\u00b0C sustained service temperature.<\/p>\n\n\n\n

                              How long does titanium investment casting typically take from order to shipment?<\/strong>
                              Lead times for aerospace\/medical titanium castings typically run 12\u201320 weeks for new parts (including tooling production, first-article inspection, and post-processing). Repeat production of qualified parts can be 8\u201312 weeks. This is significantly longer than aluminum or steel investment casting due to the complexity of post-processing and qualification requirements.<\/p>\n\n\n\n

                              R\u00e9sum\u00e9<\/h2>\n\n\n\n

                              Titanium\u2019s reactivity with oxygen is the defining fact of all titanium casting \u2014 it eliminates conventional sand casting, open-pour die casting, and any method that exposes molten metal to air. Vacuum investment casting using copper skull melters and yttria-stabilized ceramic shells is the industry-standard process<\/strong> because it handles complex geometries at near-net-shape precision while keeping the melt in a sealed vacuum environment.<\/p>\n\n\n\n

                              Sand\/graphite mold casting remains viable for large titanium structures that exceed standard investment casting furnace capacity, but requires the same vacuum environment and produces rougher surfaces and wider tolerances. Vacuum die casting handles niche high-volume thin-wall applications.<\/p>\n\n\n\n

                              For buyers: the part cost is only the beginning. Budget for HIP, alpha-case removal, heat treatment, and NDT \u2014 these post-processing steps are mandatory for aerospace and medical parts and add 30\u201370% to casting cost. Verify your supplier\u2019s equipment and certifications before sending drawings.<\/p>","protected":false},"excerpt":{"rendered":"

                              Titanium\u2019s extreme reactivity with oxygen makes standard sand casting impractical for most applications \u2014 molten titanium ignites in open air. The dominant method is vacuum investment casting, which combines a lost-wax ceramic shell process with a sealed vacuum chamber and a water-cooled copper skull melter. Other methods, including vacuum die casting and centrifugal casting, exist in […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-4471","post","type-post","status-publish","format-standard","hentry","category-blog"],"_links":{"self":[{"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/posts\/4471","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/comments?post=4471"}],"version-history":[{"count":1,"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/posts\/4471\/revisions"}],"predecessor-version":[{"id":4475,"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/posts\/4471\/revisions\/4475"}],"wp:attachment":[{"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/media?parent=4471"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/categories?post=4471"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hontitan.com\/fr\/wp-json\/wp\/v2\/tags?post=4471"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}