Bolt tsis ua hauj lwm yog ib qho teeb meem kev ntseeg siab nyob rau hauv petrochemical thiab siab -kub, siab - cov khoom siv hluav taws xob hloov pauv thaum lub sijhawm ua haujlwm ntev -. Muab ob npaug rau- xaus bolts, raws li qhov tseem ceeb ntawm cov khoom sib khi hauv cov qauv sib khi ntawm cov khoom siv hluav taws xob hauv lub taub hau, cov condensers, thiab cov hlab ntsha siab, cuam tshuam ncaj qha rau tag nrho kev ua haujlwm ruaj khov ntawm cov khoom siv. Lub taub hau lub taub hau txias hauv cov txheej txheem rov tsim dua tshiab ntawm cov roj refinery tau ntsib cov ntsia hlau tawg tsis ua haujlwm tom qab 16 xyoo ua haujlwm. Cov ntaub ntawv no nthuav tawm cov yam ntxwv ntawm kev qaug zog corrosion thiab kev ntxhov siab corrosion coupling, muab cov txiaj ntsig tseem ceeb rau kev nkag siab txog qhov tsis ua haujlwm ntawm cov fasteners hauv qhov chaw ntub dej H2S.
Cov cuab yeej ua haujlwm nyob rau hauv cov xwm txheej hauv qab no: plhaub- sab dej kub ntawm 90-100 degree, raj-sab acidic gas kub ntawm 30-35℃, thiab kev khiav hauj lwm siab ntawm 0.2 MPa thiab 0.4 MPa, feem. Qhov nruab nrab muaj ib feem ntawm H2S thiab ntsev corrosive media. bolt specification yog M20 × 2.5mm, thiab cov khoom yog 35CrMoA quenched thiab tempered steel. Raws li kev sib xyaw ua ke ntawm qhov ntev -lub sij hawm hloov thermal stress, sib dhos preload, thiab nruab nrab corrosion, ob npaug - xaus ntsia liaj qhov rooj nws thiaj li tawg ntawm lub hauv paus ntawm cov xov.
Kev soj ntsuam macroscopic qhia tau hais tias cov pob txha tawg yog nyob rau hauv cov xov hauv paus cheeb tsam, nrog ib tug zoo morphology thiab tsis pom tseeb macroscopic yas deformation. Cov khoom siv corrosion dub adhered rau saum npoo. Tom qab ntxuav, cov pob txha tawg tau nthuav tawm cov yam ntxwv ntawm kev qaug zog, nrog cov kab nrib pleb los ntawm cov xov hauv paus thiab nthuav tawm sab hauv ntawm lub kaum sab xis ntawm kwv yees li 20 degree. Tom qab ntawd nws nkag mus rau hauv thaj chaw nthuav dav sai uas nthuav tawm cov qauv radial, thaum kawg ua rau tawg sai sai. Cov yam ntxwv morphological no qhia tau hais tias cov txheej txheem tsis ua haujlwm ntawm Ob Chav Ended Tshuab Screw koom nrog ntau theem: corrosion qaug zog, kev nyuaj siab corrosion tawg, thiab tawg sai sai.
Kev txheeb xyuas tshuaj muaj pes tsawg leeg pom tau tias cov khoom siv tag nrho ua tau raws li qhov yuav tsum tau ua ntawm 35CrMoA tus qauv, qhia tias qhov tsis ua haujlwm tsis yog tshwm sim los ntawm qhov txawv txav. Kev kuaj Hardness pom tau tias Ob Chav Ended Lag Bolt muaj qhov nyuaj tag nrho, nrog cov qauv matrix feem ntau yog tsim los ntawm tempered sorbite, mus txog qib hauv zos ntawm 350-360 HV, uas yog siab dua qhov kev pom zoo rau cov pa fasteners. Metallographic tsom xam ntxiv tau nthuav tawm qee qhov kev txiav txim siab ntawm decarburization ntawm cov xov nto, nrog rau txheej decarburized ntawm kwv yees li 31 μm. Qhov chaw microstructure feem ntau yog ferrite. Hom qauv no yooj yim ua rau muaj kev ntxhov siab hauv cheeb tsam hauv kev ntxhov siab, yog li inducing tawg pib.
Scanning electron microscopy (SEM) tsom xam ntxiv qhia txog kev puas tsuaj ntawm Ob Chav Ended Hex Bolt. Pom tseeb qhov qaug zog striations tau pom nyob rau hauv cheeb tsam pib tawg, thiab cov khoom siv corrosion tau ntim cov kab nrib pleb thaum nthuav tawm. Raws li qhov tawg ntawm kev nthuav dav nce ntxiv, qhov tawg ntawm qhov tawg maj mam hloov los ntawm kev qaug zog propagation mus rau kev ntxhov siab corrosion cracking yam ntxwv, nthuav tawm cov quasi -cleavage thiab radial propagation morphology, qhia tias qhov nruab nrab corrosive tau koom nrog cov txheej txheem tawg. Lub zog dispersive spectroscopy (EDS) tsom xam pom tias cov khoom siv corrosion muaj cov sulfur siab thiab cov tshuaj chloride me me, qhia txog qhov tseem ceeb ntawm sulfide thiab chloride corrosion hauv qhov chaw pabcuam.
Kev tsom xam pom tau hais tias qhov kev ua tsis tiav no yog ib qho kev cuam tshuam corrosion thiab sulfide kev nyuaj siab corrosion cracking teeb meem tshwm sim los ntawm kev sib txuas ntawm ntau yam. Nws tsim mechanism feem ntau manifests nyob rau hauv peb yam.
Ua ntej, muaj kev ntxhov siab. Qhov ob -kawg threaded stud muaj kev ua haujlwm siab ua ntej thaum sib dhos, ua rau muaj kev ntxhov siab axial tensile tseem ceeb ntawm cov xov hauv paus. Nyob rau tib lub sijhawm, cov qauv ntab taub hau qhia txog kev ntxhov siab ntxiv. Thaum lub sijhawm ua haujlwm, thermal stress los ntawm kev nthuav dav thiab kev sib cog lus, kev vibration loads los ntawm nruab nrab ntws, thiab cyclic kev nyuaj siab thaum pib - nce thiab kaw cia cov ntsia hlau ntsia hlau nyob rau hauv lub xeev ntawm kev ntxhov siab hloov mus rau ncua sij hawm, accelerating pib tawg thiab propagation.
Qhov thib ob, cov khoom tseem ceeb ua lub luag haujlwm. Thaum 35CrMoA steel muaj lub zog siab, nws muaj kev cuam tshuam rau hydrogen -induced cracking thiab sulfide stress corrosion ntawm siab hardness. Cov txheej txheem cuam tshuam qhia tau tias hauv H2S- muaj ib puag ncig, qhov kev ntxhov siab corrosion kuj ntawm siab - lub zog steel yuav txo qis yog tias qhov hardness ntau tshaj ib qho. Nyob rau hauv cov ntaub ntawv no, lub ob - tas lub qhov (socket) ntsia hlau muaj ntau hardness thiab nthuav qhia lub zos decarburization tsis xws luag, ntxiv txo deg tawg tiv thaiv thiab tsim ib tug raug tawg cheeb tsam pib.
Thirdly, ib puag ncig yam tseem ceeb. Qhov nruab nrab muaj H2S, noo noo, thiab ntsev, ua rau muaj kev cuam tshuam corrosion nyob rau hauv electrochemical tej yam kev mob. Cov txheej txheem anodic tsim Fe2+, uas ua ke nrog cov sulfur ions los ua FeS corrosion khoom. Nyob rau tib lub sijhawm, hydrogen atoms tsim los ntawm cov tshuaj tiv thaiv cathodic tuaj yeem kis mus rau hauv cov hlau, ua rau cov tshuaj hydrogen embrittlement thiab blistering teebmeem. Raws li kev sib koom ua ke ntawm kev ntxhov siab thiab kev xeb, cov kab nrib pleb maj mam nthuav tawm ntawm lub hauv paus ntawm ob lub-kawg ntsia hlau xov, ua kom tsis zoo.
Tsis tas li ntawd, qhov ntim nthuav dav ntawm cov khoom siv corrosion ntxiv ua rau cov kab nrib pleb nthuav tawm ntawm dual - threaded screws. Qhov ntim ntawm cov khoom siv corrosion feem ntau yog 2 mus rau 4 npaug ntawm qhov ntim thawj, tsim kom muaj kev nthuav dav ntxiv hauv qhov kaw qhov tawg. Qhov no ua rau muaj kev ntxhov siab ntawm qhov tawg ntawm qhov tawg mus tas li, yog li ua kom cov txheej txheem tawg. Qhov "corrosion-kev nyuaj siab- nthuav tawm" qhov kev tawm tswv yim zoo yog qhov tseem ceeb ntawm hom kev ua tsis tiav no.
Hauv cov ntsiab lus, hom no ntawm ob npaug - tas cov ntsia hlau tsis ua haujlwm yog qhov tseem ceeb ntawm kev sib xyaw ua ke ntawm cov qauv kev ntxhov siab, cov khoom siv rhiab heev, thiab qhov chaw corrosive. Rau cov xwm txheej zoo sib xws, yuav tsum tau ua kom muaj kev txhim kho, suav nrog txo qhov hardness rhiab heev ntawm M10 ob npaug - tas screws, optimizing cov txheej txheem kev kho cua sov, tswj cov qib preload, thiab txhim kho kev sib khi thiab kev tiv thaiv corrosion tsim, los txhim kho lub sij hawm ntev - kev ntseeg siab ntawm cov qauv.
Yog xav paub ntxiv txog qhov tsis ua hauj lwm mechanism tsom xam ntawmdual- taub hau stud boltslos yog customized fastener xaiv cov lus pom zoo, thov hu rau peb pab neeg technical rau kev txhawb nqa engineering thiab kev daws teeb meem raws li koj qhov kev xav tau tshwj xeeb.
Tiv tauj peb
