Post-Weld Pickling Lub Sijhawm Li Cas (5 feeb vs. 20 feeb hauv HNO₃/HF) rau Titanium Heater Tube Hloov Alpha-Case Tshem Tawm Qhov tob thiab tom qab ua haujlwm rau Crevice Corrosion hauv 10% Citric Acid?

Tshaj tawm -weld pickling ntawm titanium welds hauv nitric-hydrofluoric acid sib tov (HNO_3/HF) tshem tawm cov pa oxygen enriched alpha- txheej txheej. luv luv pickle (5 min) tshem tawm 10-20 µm, tawm hauv qee qhov alpha{13}} rooj plaub. Lub sijhawm ntev (20 feeb) tshem tawm 40–80 µm thiab rhuav tshem cov alpha{15}} rooj plaub. Kev tshem tawm ntawm alpha-cov ntaub ntawv ua rau muaj kev tiv thaiv rau crevice corrosion nyob rau hauv 10% citric acid ntawm 80 degree. Tag nrho cov hlab ntsha (20 min) nthuav tawm 5 × ntev lub sij hawm pib lub cev dua li cov hlab me me (5 min).

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 (min) Qhov tob ntawm Alpha-case Tshem Tawm (µm) Cov Alpha Residual-case (µm) Crevice Initiation Sijhawm hauv 10% Citric Acid (hr)
0 (as-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 effect

Citric Acid (%) Kub (degree) Kev txhim kho hauv lub neej Crevice (20 min piv rau 5 min pickle)
5 80 3 × 10 80 4-5 × 15 80 5-6 × 10 100 6-8 × Pickling Time Selector Guide

Xav Tau Crevice Resistance Recommended Pickle Time (feeb) Alpha-Case Tshem Tawm Hlau Loss (µm)
Tsawg 0-5 Daim 0-20
10-15 Feem ntau 20-60
Siab 20-25 Tag Nrho 40-80
Qhov siab tshaj plaws 30 + electropolish puv + du 60–120
Kev pom zoo ntawm Engineering.

10% citric acid @ 80℃rau 20 feeb Post-weld pickling rau titanium rhaub kom tshem tawm alpha- rooj plaub tag nrho. Tshawb xyuas kev tshem tawm los ntawm kev sim microhardness (nto hardness 250 HV) Lub sij hawm pickling yog tswj kom tshem tawm cov embrittled alpha- txheej txheej thiab txhim kho cov crevice corrosion kuj.