Yuav ua li cas Post-Weld Pickling Lub Sij Hawm (5 feeb Vs. 20 feeb hauv HNO₃/HF) Rau Titanium Heater Tube Hloov Alpha-Case Tshem Tawm Qhov tob Thiab Qhov Kev Tiv Thaiv Tom Qab Rau Crevice Corrosion Hauv 10% Citric Acid?
Tso lus
Post-weld pickling hauv nitric-hydrofluoric acid sib tov (HNO₃/HF) tshem tawm cov pa oxygen-enriched alpha- txheej txheej ntawm titanium welds. Ib qho luv luv pickle (5 feeb) tshem tawm 10–20 µm, tawm hauv qee qhov alpha- rooj plaub. Lub pickle ntev dua (20 feeb) tshem tawm 40–80 µm, tshem tawm tag nrho cov alpha- rooj plaub. Hauv 10% citric acid ntawm 80 degree, crevice corrosion kuj txhim kho nrog alpha{17}} tshem tawm cov ntaub ntawv. Cov hlab ntsha tag nrho (20 feeb) muaj 5 × ntev lub sijhawm pib dua li cov hlab ntsha me me (5 feeb).
Quantitative Alpha-Kev tshem tawm cov ntaub ntawv thiab Crevice Resistance
Rau Qib 2 titanium welds tom qab pickling hauv 20% HNO₃ + 3% HF ntawm 50 degree:
| Pickle Sijhawm (feeb) | Alpha{0}}Case Tshem Tawm Qhov tob (µm) | Residual Alpha-Case (µm) | Crevice Initiation Sijhawm hauv 10% Citric Acid (teev) |
|---|---|---|---|
| 0 (raws li -welded) | 0 | 50–150 | 100–200 |
| 5 | 10–20 | 30–130 | 200–500 |
| 10 | 20–40 | 10–110 | 400–1,000 |
| 15 | 30–60 | 0–90 | 600–1,500 |
| 20 | 40–80 | 0–50 | 800–2,000 |
| 30 | 60–120 | 0 | 1,000–2,500 |
Cov txiaj ntsig ntawm Citric Acid Concentration ntawm Cov txiaj ntsig
| Citric acid (%) | Kub (degree) | Crevice Life Extension (20 feeb vs . 5 min pickle) |
|---|---|---|
| 5 | 80 | 3× |
| 10 | 80 | 4–5× |
| 15 | 80 | 5–6× |
| 10 | 100 | 6–8× |
Pickling Sijhawm Xaiv Phau Ntawv Qhia
| Yuav tsum tau Crevice Resistance | Pom zoo Pickle Time (feeb) | Alpha-Kev Tshem Tawm | Hlau poob (µm) |
|---|---|---|---|
| Tsawg | 0–5 | Ib nrab | 0–20 |
| Nruab nrab | 10–15 | Feem ntau | 20–60 |
| Siab | 20–25 | Ua kom tiav | 40–80 |
| Qhov siab tshaj plaws | 30 + electropolish | Ua kom tiav + du | 60–120 |
Kev pom zoo engineering
Rau cov cua sov titanium hauv 10% citric acid ntawm 80 degree, qhia cov ncej -weld pickling rau 20 feeb kom tshem tawm tag nrho alpha- rooj plaub. Txheeb xyuas qhov kev tshem tawm los ntawm kev sim microhardness (nto hardness<250 HV). By controlling pickling time, the engineer removes the embrittled alpha-case layer and improves crevice corrosion resistance.
