Raws li cov khoom siv hauv paus rau kev ciaj sia thiab kev loj hlob ntawm tib neeg, kev xeb ntawm cov ntaub ntawv hlau tau coj cov khoom lag luam poob rau tib neeg txhua xyoo, thiab tseem ua rau muaj kev cuam tshuam loj heev ntawm corrosion. Muaj ntau ntau yam ntawm corrosion tsis ua hauj lwm. Raws li cov ntaub ntawv txheeb cais, qhov feem ntawm cov khoom siv hlau tsis ua haujlwm los ntawm kev ntxhov siab corrosion yog qhov loj tshaj plaws.
Kev ntxhov siab corrosion cracking yog ib hom "kev puas tsuaj corrosion". Choj tsoo, dav hlau sib tsoo, roj tank tawg, thiab cov kav dej xau cuam tshuam nrog kev ntxhov siab corrosion tau ua rau muaj kev puas tsuaj loj ntawm lub neej thiab khoom vaj khoom tsev rau tib neeg.
Thaum cov khoom siv hlau ua haujlwm hauv ntau qhov chaw, corrosion yuav tshwm sim txawm tias tsis muaj load, ua rau poob phaus. Thaum muaj kev ntxhov siab, corrosion nyob rau hauv ib qho chaw tshwj xeeb yuav ua rau tawg nucleation thiab nthuav, ua rau hysteresis tawg, uas yog hu ua kev ntxhov siab corrosion.
Kev ntxhov siab corrosion cracking (SCC) yog qhov sib txawv ntawm kev tawg los ntawm kev ntxhov siab yooj yim, nws tuaj yeem tawg nyob rau hauv kev ntxhov siab heev; nws kuj tseem txawv ntawm qhov yooj yim corrosion, txawm tias qhov nruab nrab tsis muaj zog corrosive tuaj yeem ua rau muaj kev ntxhov siab corrosion tawg.
Kev ntxhov siab corrosion cracking yog ib qho "insidious" daim ntawv ntawm corrosion uas ua rau txo qis hauv cov neeg kho tshuab lub zog nrog tsawg hlau poob. Kev puas tsuaj loj heev uas nws tsis yooj yim los xyuas los ntawm kev soj ntsuam xws li, kev ntxhov siab corrosion tawg tuaj yeem ua rau cov neeg kho tshuab puas sai thiab txawm tias muaj kev puas tsuaj loj ntawm cov khoom thiab cov qauv.
Nyob rau hauv cov txheej txheem ntawm kev ntxhov siab corrosion, yog tias microcracks tsim, lawv txoj kev loj hlob yog ntau qhov kev txiav txim siab ceev dua li ntawm lwm hom kev txhim kho hauv zos.
Cov xwm txheej rau kev ntxhov siab corrosion tshwm sim
Qhov tshwm sim ntawm kev ntxhov siab corrosion tawg yuav tsum tau ua kom tau raws li peb qhov tsim nyog nyob rau tib lub sijhawm:
a) Cov ntaub ntawv rhiab heev. Raws li cov lus hais mus, yoov tsis tom cov qe seamless, thiab kev nyuaj siab corrosion cracking yuav tsum xub ua los ntawm cov ntaub ntawv rhiab heev. Qhov rhiab heev ntawm cov ntaub ntawv muab rau peb ib tug hint tias nyob rau hauv tej yam kev mob uas muaj kev nyuaj siab corrosion cracking yuav tshwm sim, cov khoom xaiv yuav tsum tau ceev faj. Austenitic stainless hlau xws li 304 yog nyob rau hauv kev pab cuam nyob rau hauv ib puag ncig uas muaj chlorine, thiab kev nyuaj siab corrosion cracking yog ib qho teeb meem uas yuav tsum tau them tshwj xeeb mloog mus rau. Austenitic stainless hlau yog lub ntsej muag-centered cubic hlau, thiab lub ntsej muag-centered cubic hlau yog tshwj xeeb tshaj yog muaj kev ntxhov siab corrosion cracking, uas yog txiav txim los ntawm cov qauv siv lead ua.
b) Ib puag ncig muaj kev ntxhov siab corrosion cracking. Txawm hais tias cov khoom yog rhiab heev, tsis muaj qhov nruab nrab uas ua rau muaj kev ntxhov siab corrosion tawg, thiab kev ntxhov siab corrosion tawg yuav tsis tshwm sim. Nws zoo li A / B sab ntawm ib npib. Ib puag ncig nruab nrab kuj yog ib qho tseem ceeb rau kev ntxhov siab corrosion cracking.
c) Txaus tensile kev nyuaj siab. Nws feem ntau suav hais tias qhov kev ntxhov siab tensile zoo li qub yog qhov tsim nyog rau kev ntxhov siab corrosion cracking. Qee tus neeg tuaj yeem nug, ua li cas txog kev hloov pauv? Kuv xav tias tej zaum yuav yog vim kev qaug zog corrosion. Vim li cas nws thiaj li hais tias kev ntxhov siab tensile txaus yuav tsum muaj rau kev ntxhov siab corrosion tawg? Vim tias nws yuav tsum tau ua kom tau raws li qhov tseem ceeb ntawm kev siv zog ntawm KISCC hauv lub xeev corrosion.
Crack morphology feem ntau suav nrog cov hauv qab no:
1. Cov kab nrib pleb feem ntau yog los ntawm cov hlau nto. Cov kev taw qhia tawg yog "dendritic", thiab lub cev yog lub ntsiab tawg, taw tes rau qhov chaw ntawm qhov tawg raws qhov kev sib tshuam.
2. Kev loj hlob tawg tuaj yeem yog transgranular, intergranular, lossis sib xyaw; feem ntau muaj cov khoom siv corrosion ntawm cov pob txha tawg
3. Transgranular ncua fractures yog feem ntau cleavage, quasi-cleavage, tej zaum tov nrog intergranular los yog dimples
4. Lub intergranular ncua kev puas tsuaj yog nyob rau hauv cov duab ntawm pob zeb qab zib, qee zaum tov nrog me me ntawm quasi-cleavage los yog intergranular thiab dimples
