Stress Corrosion Cracking (SCC) ntawm titanium cua sov raj yog hais txog nkig nkag mus rau hauv cov kab nrib pleb uas tsim los ntawm kev sib xyaw ua ke ntawm tensile residual kev ntxhov siab, kev sib dhos sab nraud thiab cov nruab nrab corrosive tshwj xeeb. Txias dabtsi yog khoov, vuam thiab yuam kev sib dhos tawm tensile kev nyuaj siab nyob rau hauv lub cev yeeb nkab. Thaum raug cov tshuaj fluoride- muaj nruab nrab, anhydrous methanol, concentrated chloride tov los yog siab -kub ntsev ib puag ncig, titanium dioxide passive zaj duab xis ruptures hauv zos nyob rau hauv tensile stress. Corrosive nruab nrab invades lub matrix raws li cov lus qhia tawg, tsav ceev nrooj propagation yam tsis muaj teeb pom kev zoo phab ntsa thinning, nws thiaj li ua rau rupture thiab to. Qhov kev ua tsis tiav no tau muab zais thiab tam sim ntawd, ua rau muaj kev pheej hmoo loj rau kev nyab xeeb rau siab -cov khoom siv cua sov titanium.
1. Coupled Initiation Mechanism ntawm Stress thiab Corrosion
Titanium vam khom TiO₂ passive zaj duab xis los tiv thaiv corrosion. Tensile stress ua rau cov yas plam ntawm cov khoom nto thiab kua muag cov oxide zaj duab xis txuas ntxiv ntawm micro- cheeb tsam. Fluoride ions thiab lwm yam corrosive Cheebtsam erodes lub titanium substrate raug rau tsim me me corrosion pits. Kev ntxhov siab concentrates ntawm lub qhov hauv qab thiab tas li fractures tshiab regenerated passive zaj duab xis, ua kom tawg cov lus qhia nyob rau hauv lub active yaj lub xeev. Cracks nthuav dav raws transgranular lossis intergranular paths nyob rau hauv kev sib koom ua ke ntawm cov neeg kho tshuab nro thiab electrochemical corrosion. Txawm hais tias kev ntxhov siab nyob deb ntawm cov khoom siv zog tuaj yeem ua rau muaj kev cuam tshuam los ntawm - phab ntsa tawg tom qab ntev - lub sij hawm cyclic nkaus, uas txawv ntawm ib qho kev qaug zog tawg tsis muaj corrosive nruab nrab kev koom tes.
2. Tej hauj lwm uas muaj kev nyuaj siab Corrosion tawg
Weld seams thiab tshav kub- thaj chaw cuam tshuam nrog vuam shrinkage tensile residual stress;
Txias- tsim khoov cov yeeb nkab seem uas khaws cov kev ua kom muaj zog tensile loj;
Flange fastening thaj chaw nrog ntau lub bolts ua ntej-tightening quab yuam qhia sab nraud tensile kev nyuaj siab;
Cov kua dej hloov pauv thaj chaw uas cov tshuaj evaporates thiab fluorine / chloride ntsev concentrate thiab precipitate;
Rigidly tsau cov yeeb nkab ntu tsis muaj peev xwm ntawm cov thermal expansion thiab contraction nyob rau hauv kub alternation.
3. Tej yam tseem ceeb ua kom SCC puas tsuaj
High concentration ntawm fluoride ions thiab siab nruab nrab kub sharply txhim khu corrosion aggressiveness;
Unrelieved residual kev nyuaj siab los ntawm dabtsi yog khoov, vuam thiab machining txheej txheem;
Tshaj -cov fasteners nruj thiab nruj kev txwv tsis pub tsim cov tensile ntxiv;
Hauv zos evaporation ua rau ntsev crystallization thiab ion enrichment ntawm cov yeeb nkab sab hauv thiab sab nrauv phab ntsa;
Nto khawb thiab indentations ua hauj lwm raws li qhov pib tawg los rhuav tshem cov kev ncaj ncees ntawm cov zaj duab xis passive.
4. Tag nrho -Txuas Kev Tiv Thaiv Kev Tiv Thaiv Kev Ntsuas Kev Ntsuas
① Ua kev tshaj tawm - ua kom txo qis kev ntxhov siab
Ua kom sov preservation kev nyuaj siab nyem kev kho mob tom qab khoov thiab welding kom tshem tawm sab hauv tensile residual kev nyuaj siab.
② Standardize pipeline installation thiab fastening hauj lwm
Siv torque wrenches los tswj bolt zawm torque; txais kev txhawb nqa zawv zawg los khaws cov nyiaj thermal expansion hloov chaw.
③ Purify circulating nruab nrab thiab siv dej yaug tu
Nruab cov khoom siv lim kom txo cov fluoride thiab chloride ion cov ntsiab lus, thiab tsis tu ncua tshem tawm crystalline sediment.
④ Optimize cov khoom xaiv rau hnyav corrosive ua hauj lwm tej yam kev mob
Txais palladium-muaj titanium alloy nrog zoo heev los tiv thaiv -SCC kev ua tau zoo rau siab -fluoride siab- qhov kub thiab txias.
⑤ Polish nto tsis xws luag thiab ntxiv dag zog rau anodic oxidation passivation
Sib tov burrs thiab khawb; ua anodic oxidation kom tuab cov zaj duab xis passive thiab txhim kho cov qauv kev ruaj ntseg.
5. Kev Tiv Thaiv Cov Teeb Meem Sib piv
表格
| Kev Ua Haujlwm & Kev Ua Haujlwm Hom | SCC Risk Level | Daim ntawv thov tswv yim |
|---|---|---|
| Cov txheej txheem txias tsis muaj kev ntxhov siab + siab fluorine nruab nrab | Tsis tshua muaj kev pheej hmoo ntawm kev tawg sai sai | Ua kom muaj kev ntxhov siab rau kev kho cua sov los yog txhim kho cov khoom siv hlau |
| Kev kho kev ntxhov siab + kev teeb tsa tus qauv + nruab nrab purification | Zoo inhibit kev ntxhov siab corrosion tawg pib thiab nthuav | Standard ntau lawm thiab kev khiav hauj lwm txij nkawm specification |
| Anodic oxidation passivation + hloov pauv kev txhawb nqa | Yam tsawg kawg cracking nyiam nyob rau hauv kev ua hauj lwm hnyav | Cov txheej txheem nyiam rau siab -kev pheej hmoo corrosive cua sov kav dej |
Xaus
Kev ntxhov siab corrosion tawg ntawm titanium cua sov raj yog sib koom ua ke los ntawm kev ntxhov siab tensile rhuav cov zaj duab xis passive thiab xaiv electrochemical dissolution ntawm cov lus qhia tawg. Cov tswv yim tiv thaiv tseem ceeb muaj xws li tshem tawm cov kev ntxhov siab sab hauv thiab sab nraud, thaiv cov khoom siv hauv zos ntawm corrosive ions, tshem tawm qhov tsis xws luag ntawm qhov chaw tawg thiab txhim kho cov kev tiv thaiv kev ruaj ntseg ntawm cov txheej tiv thaiv nto. Kev tswj hwm nruj ntawm kev siv thev naus laus zis, ntawm - qhov chaw tsim kho thiab kev saib xyuas txhua hnub tuaj yeem tiv thaiv kev nkag mus sai sai los ntawm kev ntxhov siab corrosion tawg ntawm titanium cua sov raj.
