Raccords en alliage en alliage en titane

 

je. Core Content and Scope of ASTM B363 Titanium Alloy Butt-Welding Fittings

The ASTM B363 standard comprehensively governs titanium and titanium alloy butt-welding fittings, principalement pour un service résistant à la corrosion et à haute température. Les spécifications clés incluent:

1. Material Sources and Processing Requirements
   • Raw materials must comply with ASTM standards: assiettes (B265), bars / billettes (B348), sorts (B381), tuyaux sans couture (B861), and welded pipes (B862).
   • Manufacturing processes include forging, extrusion, rolling, flexion, soudage, etc., with strict avoidance of harmful defects.
2. Dimensions et tolérances
   • Fittings must conform to ASME B16.9 and MSS SP 43 normes.

• Seamless fittings: ½” à 8″ tailles; wall thickness SCH 5S to SCH 80S.
• Welded fittings: ½” to 16″ tailles; same wall thickness range.
  • Examples: Grade 2 seamless 90° elbows (2″ & 4″, SCH 40), concentric reducer (4″×2½″, SCH 40).

3. Heat Treatment and Inspection
   • Mandatory stress-relieving annealing for optimized mechanical properties.
   • Contrôles non destructifs: 100% TP (penetrant testing) for surfaces, RT (tests radiographiques) for welds.

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Ii. Types and Applications of Titanium Butt-Welding Fittings

(A) Types communs

Type de	Fonction & Spécifications
Coudes	45°, 90°, 180° bends; long radius (LR) or short radius (RS) for directional changes.
Réducteurs	Concentric/eccentric designs for pipe diameter transitions (par exemple., 4″×2½″ SCH 40).
T-shirts	Equal/unequal tees, lateral tees for fluid branching.
D’autres	Capuchons, U-bends, Talon de joint lapin se termine, crosses.

(B) Key Industries

1. Chemical & Pétrochimique
   • Resistant to acids/alkalis in reactors, Échangeurs de chaleur.
2. Aérospatial
   • Fuel/hydraulic systems: high strength-to-weight ratio reduces structural weight.
3. Génie maritime
   • Seawater desalination, subsea pipelines: superior corrosion resistance vs. en acier inoxydable.
4. Energy & Puissance
   • High-temperature applications (par exemple., nuclear cooling systems), serviceable up to 500°C.

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III. Processus de fabrication & Spécifications techniques

(A) Material Processing

• Melting: Vacuum consumable electrode arc melting or electron beam melting for purity.
• Forgeage: Multi-step upsetting/drawing to refine microstructure.
• Extrusion: Performed at 750–1300°C with glass lubricants; extrusion ratio ~100.

(B) Formation & Soudage

• Seamless fittings: Piercing extrusion or cross-rolling.
• Welded fittings: Compliance with ASTM B861/B862; post-weld annealing (450–650°C for 1–5 hours).

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Iv. Normes dimensionnelles: ASME B16.9 vs. MSS SP 43

Paramètre	ASME B16.9	MSS SP 43
Portée	Carbon/alloy/stainless steel (NPS ½”–48″)	Thin-wall stainless/nickel alloys (SCH 5S/10S)
OD Tolerance (NPS≤4″)	±0.03″	±0.03″ (NPS≤4″); +0.06″/-0.03″ (NPS≥5″)
Pressions nominales	SCH 10–XXS (full range)	SCH 5S/10S only; short-pattern lap-joints

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V. Impact of Stress-Relieving Annealing

1. Propriétés mécaniques
   • Strength reduction: Tensile/yield strength drops 5–10% (par exemple., TC18 alloy: 1100 MPa → 950 MPa).
   • Ductility improvement: Elongation increases 20–30%; enhanced impact toughness.
2. Microstructure
   • Above 650°C: Reduced α-phase, increased metastable β-phase.
   • Recommended for TA18 alloy: 450–500°C × 3–5 hours.

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Vi. Product Examples (ASTM B363 Grade 2)

Produit	Taille	Épaisseur de paroi	la norme
90° Coude	2″ & 4″	SCH 40	ASME B16.9
Concentric Reducer	4″×2½″	SCH 40	MSS SP 43

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VII. Quality Control & Essai

• CND: 100% RT for welds, PT for surface defects.
• Dimensional checks: Laser scanning/CMM for compliance (par exemple., elbow angle tolerance ±0.03°–0.75°).

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VIII. Industry Trends & Innovations

• Material advancements: High vanadium/molybdenum alloys (par exemple., WPT23) pour >600°C service.
• Process innovation: Fabrication additive (3D printing) for complex geometries; lead time reduced to 10–15 days.

This translation provides a technical overview of ASTM B363 titanium alloy fittings, covering standards, manufacturing, candidatures, and emerging technologies for engineering reference.