Chromium depletion ntawm grain ciam teb
Kev kho cua sov tsis raug (piv txwv li, dhau - kev laus lossis qeeb txias tom qab vuam) yuav txhawb cov nag lossis daus ntawm chromium - nplua nuj carbides (xws li Cr₂₃C₆) ntawm cov ciam teb. Qhov no ua rau kev tsim ntawmchromium - thaj chaw depletednyob ib sab ntawm cov ciam teb, qhov twg cov ntsiab lus chromium poob qis dua qhov tseem ceeb (kwv yees li 12% los ntawm huab hwm coj) yuav tsum tau tsim kom muaj kev ruaj khov passivation zaj duab xis. Cov cheeb tsam depleted no dhau los ua qhov chaw tshwj xeeb rau kev pib corrosion, uas yooj yim induce intergranular stress corrosion cracking.
Precipitation ntawm brittle theem
Kev sib ntxiv ntawm cov ntsiab lus ntxiv (piv txwv li, Nb, Ta, W) yuav txhawb kev tsim cov nkig intermetallic theem (xws li TCP theem, σ theem) los yog ntxhib MC - hom carbides hauv cov hlau. Cov theem nkig no yuav ua rau muaj kev ntxhov siab nyob rau theem - matrix interface, thiab txo qhov toughness ntawm alloy matrix, ua rau cov alloy muaj kev cuam tshuam rau kev ntxhov siab corrosion tawg nyob rau hauv kev sib xyaw ua haujlwm ntawm kev ntxhov siab thiab corrosion.
Grain loj thiab morphology
Coarse - grained npib tsib xee - raws li cov alloys muaj tsawg dua cov ciam teb, thiab cov kab nrib pleb tuaj yeem nthuav tawm sai sai raws li cov ciam teb ib zaug, uas qhia tau tias SCC siab dua. Hauv qhov sib piv, nplua - grained alloys tuaj yeem cuam tshuam kev tawg ntawm kev nthuav tawm los ntawm kev nce tus lej ntawm cov ciam teb, tab sis ultra - cov nplej nplua nuj tuaj yeem ua rau muaj kev pheej hmoo ntawm SCC vim tias muaj feem ntau ntawm cov ciam teb nplej thiab qhov nyiam ntawm cov ciam teb zawv zawg.
Residual stress
Qhov no yog qhov kev ntxhov siab tshaj plaws rau npib tsib xee - raws li cov khoom siv hlau, feem ntau yog muab los ntawmkev ua tsis tsim nyog thiab kev tsim khoom, xws li txias sib sau, vuam, kho cua sov, thiab machining. Piv txwv li, lub voj voog thermal thaum lub sij hawm vuam yuav ua rau qhov tsis sib xws ntawm kev nthuav dav thiab kev cog lus ntawm thaj chaw weld thiab tshav kub - thaj tsam cuam tshuam, ua rau muaj kev ntxhov siab ntau ntxiv.
Siv kev ntxhov siab
Nws hais txog cov khoom siv sab nraud uas tau los ntawm cov hlau thaum lub sijhawm ua haujlwm, xws li cov khoom siv thauj khoom ntawm aero - cav turbine hniav thiab lub siab load ntawm cov khoom siv tshuaj lom neeg. Thaum lub zog tensile thov tshaj ib qho chaw pib, nws yuav ua kom qhov pib thiab nthuav tawm ntawm cov kab nrib pleb.
Chloride - muaj ib puag ncig
Chloride ions (Cl⁻) yog cov feem ntau SCC - inducing ions rau nickel - raws li alloys. Nyob rau hauv siab - kub thiab siab - concentration chloride media (xws li seawater, industrial brine, thiab chloride - uas muaj dej txias), chloride ions yuav nkag mus thiab rhuav tshem cov zaj duab xis passivation ntawm lub alloy nto, tsim pitting corrosion, uas tom qab ntawd tsim mus rau hauv kev nyuaj siab corrosion tawg nyob rau hauv tensile stress.
Caustic media ib puag ncig
Nyob rau hauv siab - kub thiab siab - concentration alkaline daws (xws li NaOH, KOH), npib tsib xee - raws li alloys yog nquag muscaustic kev nyuaj siab corrosion cracking. Piv txwv li, nyob rau hauv lub chav generator ntawm nuclear fais fab nroj tsuag, cov concentrated alkaline ib puag ncig nyob rau hauv lub crevice yuav induce SCC ntawm npib tsib xee - raws li alloy tshav kub exchangers raj.
Siab - dej kub thiab qhov chaw ib puag ncig
Nyob rau hauv siab - dej kub thiab chav tshuab (xws li boiler kav thiab chav turbines), yaj oxygen thiab hydrogen ions nyob rau hauv dej yuav ua rau kom cov electrochemical corrosion ntawm cov hlau, thiab koom tes nrog tensile kev nyuaj siab induce SCC.
Kub
SCC ntawm npib tsib xee - raws li alloys yog qhov kub thiab txias - nyob ntawm qhov tshwm sim. Feem ntau, SCC susceptibility nce nrog qhov nce ntawm qhov kub thiab txias nyob rau hauv ib qho chaw, vim tias qhov kub thiab txias yuav ua rau cov tshuaj tiv thaiv electrochemical thiab diffusion tus nqi ntawm corrosive ions.
Crevice thiab stagnant tej yam kev mob
Crevices (xws li kev sib txuas ntawm bolts thiab txiv ntseej, qhov sib txuas sib txuas ntawm qhov sib txuas) thiab cov chaw xov xwm stagnant yog nquag tsim.concentration cell, ua rau muaj kev nplua nuj ntawm corrosive ions thiab acidification lossis alkalization ntawm ib puag ncig hauv zos, uas ua rau muaj kev pheej hmoo ntawm SCC.
