أنا. 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, في المقام الأول لخدمة مقاومة للتآكل ودرجات الحرارة العالية. تشمل المواصفات الرئيسية:
- Material Sources and Processing Requirements
- Raw materials must comply with ASTM standards: لوحات (B265), الحانات/المليارات (B348), المطروق (B381), أنابيب سلسة (B861), and welded pipes (B862).
- Manufacturing processes include forging, قذف, rolling, الانحناء, لحام, إلخ, with strict avoidance of harmful defects.
- الأبعاد والتسامح
- Fittings must conform to ASME B16.9 and MSS SP 43 المعايير.
- Seamless fittings: ½” إلى 8″ الأحجام; wall thickness SCH 5S to SCH 80S.
- Welded fittings: ½” to 16″ الأحجام; same wall thickness range.
- Examples: درجة 2 seamless 90° elbows (2″ & 4″, SCH 40), concentric reducer (4″×2½″, SCH 40).
- Heat Treatment and Inspection
- Mandatory stress-relieving annealing for optimized mechanical properties.
- اختبار غير مدمر: 100% حزب العمال (penetrant testing) for surfaces, ر.ت (الاختبار الشعاعي) for welds.
الثاني. Types and Applications of Titanium Butt-Welding Fittings
(A) الأنواع الشائعة
| نوع | وظيفة & المواصفات |
|---|---|
| المرفقين | 45°, 90°, 180° bends; long radius (إل آر) or short radius (ريال) for directional changes. |
| مخفضات | Concentric/eccentric designs for pipe diameter transitions (مثل, 4″×2½″ SCH 40). |
| المحملات | Equal/unequal tees, lateral tees for fluid branching. |
| الآخرين | قبعات, U-bends, ينتهي كعب الرصيف, crosses. |
(ب) Key Industries
- Chemical & البتروكيماويات
- Resistant to acids/alkalis in reactors, المبادلات الحرارية.
- الفضاء
- Fuel/hydraulic systems: high strength-to-weight ratio reduces structural weight.
- الهندسة البحرية
- Seawater desalination, subsea pipelines: superior corrosion resistance vs. الفولاذ المقاوم للصدأ.
- Energy & قوة
- High-temperature applications (مثل, nuclear cooling systems), serviceable up to 500°C.
ثالثا. عمليات التصنيع & المواصفات الفنية
(A) Material Processing
- Melting: Vacuum consumable electrode arc melting or electron beam melting for purity.
- تزوير: Multi-step upsetting/drawing to refine microstructure.
- البثق: Performed at 750–1300°C with glass lubricants; extrusion ratio ~100.
(ب) تشكيل & لحام
- Seamless fittings: Piercing extrusion or cross-rolling.
- Welded fittings: Compliance with ASTM B861/B862; post-weld annealing (450–650°C for 1–5 hours).
رابعا. معايير الأبعاد: ASME B16.9 vs. MSS SP 43
| المعلمة | أسم B16.9 | MSS SP 43 |
|---|---|---|
| نِطَاق | 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″) |
| تقييمات الضغط | SCH 10–XXS (full range) | SCH 5S/10S only; short-pattern lap-joints |
V. Impact of Stress-Relieving Annealing
- الخواص الميكانيكية
- Strength reduction: Tensile/yield strength drops 5–10% (مثل, TC18 alloy: 1100 MPa → 950 الآلام والكروب الذهنية).
- Ductility improvement: Elongation increases 20–30%; enhanced impact toughness.
- البنية المجهرية
- Above 650°C: Reduced α-phase, increased metastable β-phase.
- Recommended for TA18 alloy: 450–500°C × 3–5 hours.
السادس. Product Examples (ASTM B363 Grade 2)
| المنتج | الحجم | سمك الجدار | اساسي |
|---|---|---|---|
| 90كوع ° | 2″ & 4″ | SCH 40 | أسم B16.9 |
| Concentric Reducer | 4″×2½″ | SCH 40 | MSS SP 43 |
VII. Quality Control & الاختبار
- NDT: 100% RT for welds, PT for surface defects.
- Dimensional checks: Laser scanning/CMM for compliance (مثل, elbow angle tolerance ±0.03°–0.75°).
VIII. Industry Trends & Innovations
- Material advancements: High vanadium/molybdenum alloys (مثل, WPT23) من أجل >600°C service.
- Process innovation: Additive manufacturing (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, التطبيقات, and emerging technologies for engineering reference.
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