Overheating xwm txheej tuaj yeem txiav txim siab los ntawm kev soj ntsuam metallographic ntawm kev puas tsuaj tsis tuaj yeem xws li lis ciam oxidation, voids, lossis hauv zos melting. Cov yam ntxwv no qhia tau hais tias cov khoom tau dhau los ua tsis tiav thiab tsis tuaj yeem kho los ntawm kev kho cua sov.
1. Cov yam ntxwv zoo nyob rau hauv Metallographic Microscope
Grain Boundary Oxidation: Nyob rau hauv lub tshuab tsom, lub network dub oxide pom nyob rau ntawm cov ciam teb, qhia tias oxygen tau nkag mus rau hauv cov ciam teb, ua rau muaj kev sib raug zoo ntawm lub zog.
Grain Boundary Voids: me me pores los yog kab nrib pleb tshwm nyob rau hauv thaj tsam ciam teb, uas yog cov pov thawj ncaj qha ntawm intensified atomic diffusion thiab tsis muaj zog grain ciam teb nyob rau hauv high kub.
Localized Melting (Remelted Balls): Rounded kab ntawm cov kua theem (remelted balls) tshwm nyob rau ntawm cov nplej ciam teb junctions, qhia tias qhov kub thiab txias tau tshaj cov khoom melting point thiab micro- cheeb tsam melting tau tshwm sim.
Intergranular Fracture: Txoj kev puas tsuaj txuas ntxiv raws li thaj tsam ntawm cov qoob loo, thiab cov pob zeb tawg muaj "pob zeb-zoo li tawg"- greyish-dawb, tsis muaj xim hlau, thiab nrog lub ntsej muag zoo nkauj.
Kev Txiav Txim Siab: Kev ntsuas ntsuas raws li GB / T 6394. Yog tias pom ib qho ntawm cov yam ntxwv saum toj no, nws tuaj yeem lees paub tias yog overheating.
2. Kev tshwm sim txawv txav hauv Macroscopic thiab kev siv
Pwm Deg Discoloration: Overheated cheeb tsam pom xiav -liab, greyish-dawb, los yog tev tshwm sim, qhia txog microstructural degradation.
Nquag Cracking: Intergranular tawg tshwm nyob rau hauv siab - qhov chaw kub xws li kub khiav nozzles thiab manifolds, thiab rov tshwm sim sai tom qab kho.
Sudden Performance Degradation: Hardness thiab cuam tshuam toughness txo qis, thiab lifespan luv luv los ntawm ntau tshaj 50% nyob rau hauv tib yam kev ua haujlwm.
Ceeb toom tshwj xeeb: Thaum overheating tau lees paub, cov khoom siv tsis tuaj yeem thiab cov khoom yuav tsum tau hloov. Kev siv txuas ntxiv yuav ua rau muaj kev nyab xeeb.
3. Cov txheej txheem txiav txim pom zoo
Sampling thiab Testing: Nqa cov qauv los ntawm qhov xav tias muaj cua sov thiab npaj cov qauv metallographic;
Corrosion Observation: Tom qab etching nrog 4% nitric acid cawv, tshuaj xyuas lub teb chaws ciam teb nyob rau hauv ib tug 100 × - 200 × microscope;
Kev Tshawb Fawb Txog Kev Tshawb Fawb: Ua qhov kev txiav txim zaum kawg raws li keeb kwm cua sov (txawm tias qhov kub siab tshaj 1150 degree), tawg morphology, thiab cov txiaj ntsig kev ua haujlwm.
