440C vs 440B Stainless hlau: Siab-Hardness Martensitic Qib

 

Dab tsi yog cov tshuaj muaj pes tsawg leeg, cov khoom siv kho tshuab, thiab kev siv thawj zaug ntawm 440C thiab 440B?
Ob qib yog ib feem ntawm 440 series martensitic stainless hlau, uas muaj cov ntsiab lus chromium siab (16-18%) thiab cov pa roj carbon tseem ceeb. Qib 440C (UNS S44004) muaj cov pa roj carbon ntau tshaj ntawm 0.95-1.20%. Qib 440B (UNS S44003) muaj cov ntsiab lus nruab nrab-siab carbon ntawm 0.75-0.95%. Qhov sib txawv no tso cai rau 440C kom ua tiav qhov nyuaj ntawm HRC 58-60 tom qab kev kho cua sov, thaum 440B nce txog HRC 56-58, kev ua lag luam siab tshaj plaws rau kev txhim kho toughness. Ob leeg yog hlau nplaum, muab kev hnav zoo, thiab muaj kev tiv thaiv corrosion tsis zoo. Lawv feem ntau yog siv rau cov khoom siv bearing, valve qhov chaw, cov hniav zoo nkauj, cov cuab yeej phais, thiab lwm qhov chaw uas qhov hnyav saum npoo yog qhov tseem ceeb.

Yuav ua li cas cov ntsiab lus carbon dictate xaiv ntawm qhov siab tshaj plaws hardness thiab toughness?
Carbon yog lub hauv paus hardening. Cov pa roj carbon ntau dua hauv 440C ua rau muaj qhov ntim ntau dua ntawm cov tawv chromium carbides, muab nws qhov ua tau zoo tshaj plaws thiab ua kom zoo tshaj plaws hauv tsev neeg stainless. Txawm li cas los xij, qhov no kuj txo qhov toughness, ua rau nws nkig nyob rau hauv kev cuam tshuam loj heev. Cov pa roj carbon qis me ntsis hauv 440B yields marginally tsawg carbides, muab me me tab sis muaj txiaj ntsig kev txhim kho hauv kev poob siab thiab ua haujlwm ntev ntawm tus nqi ntawm qhov kawg hardness. Qhov kev xaiv yog qhov tseem ceeb ntawm qhov tseem ceeb ntawm kev hnav lub neej (440C) lossis kev cuam tshuam (440B).

Kev kho cua sov ua lub luag haujlwm dab tsi hauv kev ua tiav qhov kev xav tau ntawm cov qib no?
Kev kho cua sov yog cov txheej txheem txhais uas qhib lawv lub peev xwm. Ob leeg yuav tsum tau austenitizing meej, quenching, thiab tempering. Cov ntsiab lus carbon siab, tshwj xeeb tshaj yog nyob rau hauv 440C, xav kom tswj qhov kub thiab txias thaum lub sij hawm austenitizing kom yaj tag nrho carbides yam tsis ua rau cov nplej loj hlob. Tempering kho qhov kawg hardness thiab kev ntxhov siab nyem. Kev kho cua sov tsis zoo tuaj yeem ua rau cov austenite khaws cia, tsis txaus hardness, lossis ntau dhau brittleness. Txhawm rau kom tau txais txiaj ntsig zoo ib yam, cov qhab nia no yuav tsum tau ua tiav los ntawm cov kws tshaj lij nrog cov cua sov cua sov kom tiv thaiv qhov decarburization.

Nyob rau hauv cov ntawv thov tshwj xeeb twg yog ib qib kom pom tseeb dua lwm tus?
Xaiv 440C unequivocally rau daim ntaub ntawv thov qhov siab tshaj plaws hardness thiab hnav tsis kam nyob rau hauv siab load nrog tsawg poob siab. Qhov no suav nrog cov pob bearings precision thiab kev sib tw hauv aerospace, siab - hnav cov twj tso kua mis, thiab cov hniav rau cov riam uas tau txais txiaj ntsig zoo rau kev tuav ruaj khov heev. Opt rau 440B thaum cov khoom yuav tsum muaj kev cuam tshuam ntau dua, khoov kev ntxhov siab, lossis kev thauj khoom cyclic. Piv txwv suav nrog qee cov cuab yeej ntxig, siab - kev nyuaj siab cutlery, thiab cov cuab yeej phais zoo li cov pob txha chisels uas qhov sib npaug ntawm qhov tawv thiab pob txha tiv thaiv yog qhov tseem ceeb.

Yam tseem ceeb dab tsi yuav tsum tus neeg yuav khoom lossis tus kws tsim khoom ntsuas thaum qhia txog ntawm 440B thiab 440C?
Qhov kev txiav txim siab yuav tsum tau coj los ntawm kev soj ntsuam kev pheej hmoo. Ua ntej, txheeb xyuas hom kev ua tsis tiav: nws puas hnav lossis puas tsuaj zawv plaub hau? Thib ob, xav txog qhov chaw ua haujlwm - khov kho siab nyiam 440C; cov kev cuam tshuam tsis tuaj yeem pom zoo 440B. Thib peb, tus account rau kev tsim khoom: 440C qhov hnyav hnyav ua rau qhov kawg machining lossis sib tsoo nyuaj dua tom qab-kub- kho. Thaum kawg, ua tus nqi - kev txheeb xyuas qhov txiaj ntsig. Thaum ob qib muaj cov nqi khoom zoo sib xws, tag nrho cov nqi ntawm kev ua tsis tiav (lub sijhawm poob qis, kev nyab xeeb) feem ntau tshaj tus nqi pib. Nco ntsoov qhia qhov tseeb qib thiab qhov xav tau kev kho cua sov (xws li, hardened thiab tempered rau HRC 58) hauv cov ntaub ntawv yuav khoom.