Hvordan korrelerer indholdet af indeslutninger (som målt ved ASTM E45, type A vs. type C) i et grad 2 titanium-varmerør med grubetætheden i en 0,5 % bromopløsning ved 50 grader?
Læg en besked
In Grade 2 titanium, inclusions-primarily Ti₂Fe particles-act as pitting initiation sites. ASTM E45 classifies inclusions by type: Type A (sulfides, rare in titanium), Type B (aluminates), Type C (silicates), and Type D (globular oxides). In titanium, iron-rich inclusions (Type D) are most common and most detrimental. Higher inclusion content correlates directly with higher pitting density in bromine solutions. A severe inclusion rating (E45 rating >2) resulterer i grubetæthed 5-10× højere end et rent materiale (E45-klassificering<1).
Kvantitativ Pitting Density vs. Inclusion Rating
I 0,5 % Br₂ ved 50 grader i 500 timer:
| ASTM E45 Inclusion Rating | Ti₂Fe-partikeldensitet (partikler/mm²) | Grubetæthed (gruber/cm²) | Maks. huldybde (µm) |
|---|---|---|---|
| <0.5 (very clean) | <50 | 5–20 | 20–50 |
| 0,5-1,0 (ren) | 50–150 | 20–60 | 40–100 |
| 1,0-1,5 (moderat) | 150–300 | 50–150 | 80–180 |
| 1,5-2,0 (moderat-tungt) | 300–600 | 100–300 | 120–250 |
| >2.0 (tung) | >600 | 200–500 | 200–400 |
Inklusionstype vs. Pitting-alvorlighed
| Inklusionstype (ASTM E45) | Typisk i titanium | Pitting sværhedsgrad (relativ) |
|---|---|---|
| Type A (sulfider) | Meget sjælden | Lav |
| Type B (aluminater) | Sjælden | Lav |
| Type C (silikater) | Lejlighedsvis | Moderat |
| Type D (globulære oxider/Fe-rig) | Fælles | Høj |
Inklusionskontrolvejledning
| Påkrævet grubetæthed (gruber/cm²) | Maksimal ASTM E45-vurdering | Anbefalet fremstilling |
|---|---|---|
| <20 | <0.5 | VAR-smeltning (vakuumbue-omsmeltning) |
| 20–50 | <1.0 | Dobbelt VAR |
| 50–100 | <1.5 | Enkelt VAR + rent råmateriale |
| >100 | >2.0 | Anbefales ikke til Br₂-service |
Teknisk anbefaling
For bromservice ved 50 grader, specificer titaniumrør med ASTM E45 inklusionsklassificering<1.0 (clean). Use double vacuum arc remelted (VAR) material for lowest inclusion content. By controlling inclusion content, the engineer reduces pitting density in aggressive bromine solutions.
