Txhua qhov kev xeem raws tu qauv (Brinell, Rockwell, Vickers) muaj cov txheej txheem tshwj xeeb rau cov khoom hauv kev sim.Rockwell t-test yog qhov muaj txiaj ntsig zoo rau kev sim cov kav dej nyias nyias los ntawm kev txiav cov yeeb nkab ntev thiab tshawb xyuas cov yeeb nkab phab ntsa los ntawm txoj kab nruab nrab sab hauv es tsis yog sab nraud.
Kev xaj cov kav dej yog me ntsis zoo li mus rau lub khw muag tsheb thiab xaj tsheb lossis tsheb thauj khoom.Tam sim no muaj ntau txoj kev xaiv uas tso cai rau cov neeg yuav khoom tuaj yeem hloov kho lub tsheb hauv ntau txoj hauv kev - xim sab hauv thiab sab nrauv, luas tej pob khoom, kev xaiv sab nrauv, xaiv powertrain, thiab lub suab kaw lus uas yuav luag zoo li kev lom zem hauv tsev.Nrog rau tag nrho cov kev xaiv no, tej zaum koj yuav tsis txaus siab rau lub tsheb tsis muaj frills.
Qhov no siv rau cov kav dej steel.Nws muaj ntau txhiab txoj kev xaiv los yog specifications.Ntxiv rau qhov ntev, cov lus qhia tshwj xeeb hais txog cov khoom siv tshuaj lom neeg thiab ntau yam khoom siv xws li lub zog tsawg kawg nkaus (MYS), lub zog tensile kawg (UTS), thiab qhov tsawg kawg nkaus elongation rau qhov tsis ua haujlwm.Txawm li cas los xij, ntau hauv kev lag luam - engineers, purchasing agents, thiab manufacturers - siv cov kev lag luam shorthand thiab hu rau "yooj yim" welded kav thiab sau tsuas yog ib tug yam ntxwv: hardness.
Sim xaj lub tsheb raws li ib tus yam ntxwv ("Kuv xav tau lub tsheb nrog kev sib kis tsis siv neeg"), thiab nrog tus muag khoom koj yuav tsis mus deb.Nws yuav tsum tau sau ib daim ntawv nrog ntau txoj kev xaiv.Qhov no yog rooj plaub ntawm cov kav hlau: txhawm rau kom tau txais cov yeeb nkab haum rau daim ntawv thov, cov chaw tsim khoom siv yeeb nkab xav tau cov ntaub ntawv ntau dua li qhov tawv.
Yuav ua li cas hardness tau txais kev hloov pauv rau lwm yam khoom siv tshuab?Tej zaum nws pib nrog cov yeeb nkab manufacturers.Vim tias kev sim hardness yog ceev, yooj yim, thiab yuav tsum tau cov cuab yeej pheej yig, cov neeg muag yeeb nkab feem ntau siv cov kev sim hardness los sib piv ob hom yeeb nkab.Txhua yam lawv yuav tsum tau ua ib qho kev xeem hardness yog ib tug du piece ntawm cov yeeb nkab thiab ib tug xeem rig.
Cov yeeb nkab hardness yog ze ze rau UTS thiab txoj cai ntawm tus ntiv tes xoo (feem pua lossis feem pua ntawm qhov ntau) yog qhov muaj txiaj ntsig zoo rau kev kwv yees MYS, yog li nws yooj yim pom tias kev ntsuas qhov tawv tawv yuav ua li cas thiaj haum rau lwm yam khoom.
Tsis tas li ntawd, lwm yam kev sim no kuj nyuaj.Thaum kev sim hardness tsuas yog siv li ib feeb ntawm ib lub tshuab, MYS, UTS thiab elongation tests yuav tsum tau ua qauv npaj thiab kev nqis peev tseem ceeb hauv cov khoom siv hauv chav kuaj loj.Hauv kev sib piv, tus neeg teb xov tooj yeeb nkab ua tiav qhov kev sim hardness hauv vib nas this, thaum tus kws tshaj lij metallurgist ua qhov ntsuas tensile hauv ob peb teev.Ua ib qho kev sim hardness tsis nyuaj.
Qhov no tsis tau txhais hais tias engineering yeeb nkab manufacturers tsis siv hardness xeem.Nws muaj kev nyab xeeb los hais tias feem coob ua qhov no, tab sis txij li thaum lawv ntsuas cov cuab yeej rov ua dua thiab rov ua dua tshiab thoob plaws txhua yam khoom siv ntsuas, lawv paub zoo txog cov kev txwv ntawm kev xeem.Feem ntau ntawm lawv siv nws los ntsuas qhov hardness ntawm lub raj ua ib feem ntawm cov txheej txheem tsim khoom, tab sis tsis txhob siv nws los ntsuas cov khoom ntawm lub raj.Nws tsuas yog kev xeem dhau / tsis ua haujlwm.
Vim li cas kuv thiaj yuav tsum paub MYS, UTS thiab yam tsawg kawg nkaus elongation?Lawv qhia txog kev ua haujlwm ntawm lub raj sib dhos.
MYS yog qhov tsawg kawg nkaus quab yuam uas ua rau cov khoom deformation mus tas li.Yog tias koj sim me ntsis khoov ib daim hlau ncaj (xws li lub hanger) thiab tso lub siab, ib qho ntawm ob yam yuav tshwm sim: nws yuav rov qab mus rau nws qhov qub qub (txoj cai) lossis nyob twj ywm.Yog tias tseem ncaj, ces koj tsis tau hla MYS tseem.Yog tias nws tseem khoov, koj nco.
Tam sim no tuav ob kawg ntawm cov hlau nrog pliers.Yog tias koj tuaj yeem tawg ib nrab, koj tau ua nws dhau los UTS.Koj rub nws nyuaj thiab koj muaj ob daim hlau los qhia koj qhov kev siv zog superhuman.Yog tias qhov ntev ntawm cov xaim yog 5 ntiv tes, thiab ob qhov ntev tom qab tsis ua haujlwm ntxiv txog 6 ntiv tes, cov hlau yuav ncav cuag 1 nti, lossis 20%.Kev ntsuas tensile tiag tiag yog ntsuas nyob rau hauv 2 ntiv tes ntawm qhov chaw so, tab sis tsis muaj teeb meem dab tsi - txoj kab nro lub tswv yim qhia txog UTS.
Cov qauv hlau micrograph yuav tsum tau txiav, polished, thiab etched nrog cov kua qaub tsis muaj zog (feem ntau yog nitric acid thiab cawv) kom pom cov nplej.100x magnification feem ntau yog siv los tshuaj xyuas cov nplej nplej thiab txiav txim siab lawv qhov loj me.
Hardness yog ib qho kev ntsuam xyuas ntawm cov khoom siv los cuam tshuam li cas.Xav txog tias qhov ntev ntawm tubing yog muab tso rau hauv lub vise nrog serrated puab tsaig thiab shaken kom kaw lub vise.Ntxiv nrog rau kev sib koom ua ke ntawm cov yeeb nkab, vise puab tsaig tawm ib qho imprint rau saum npoo ntawm cov yeeb nkab.
Qhov no yog li cas qhov kev sim hardness ua haujlwm, tab sis nws tsis zoo li ntxhib.Qhov kev ntsuam xyuas muaj qhov tswj tau qhov loj me thiab tswj lub siab.Cov rog no deform qhov chaw, tsim indentations lossis indentations.Qhov loj los yog qhov tob ntawm cov hniav txiav txim siab qhov hardness ntawm cov hlau.
Thaum ntsuas cov hlau, Brinell, Vickers thiab Rockwell hardness tests feem ntau siv.Txhua tus muaj nws tus kheej qhov ntsuas, thiab qee qhov ntawm lawv muaj ntau txoj kev sim xws li Rockwell A, B, C, thiab lwm yam. Rau cov kav hlau steel, ASTM A513 specification yog hais txog Rockwell B test (abbreviated li HRB lossis RB).Lub Rockwell Test B ntsuas qhov sib txawv ntawm kev nkag mus ntawm lub 1⁄16 inch inch steel pob rau hauv steel ntawm lub teeb preload thiab ib qho yooj yim load ntawm 100 kgf.Ib qho txiaj ntsig zoo rau cov qauv me me yog HRB 60.
Cov kws tshawb fawb cov ntaub ntawv paub tias hardness muaj kev sib raug zoo nrog UTS.Yog li ntawd, qhov muab hardness kwv yees UTS.Ib yam li ntawd, cov yeeb nkab chaw tsim khoom paub tias MYS thiab UTS muaj feem cuam tshuam.Rau cov kav dej welded, MYS feem ntau yog 70% txog 85% UTS.Tus nqi pes tsawg yog nyob ntawm cov txheej txheem tsim cov raj.Lub hardness ntawm HRB 60 sib raug rau UTS 60,000 phaus ib square inch (PSI) thiab txog 80% MYS, uas yog 48,000 PSI.
Feem ntau cov yeeb nkab specification rau kev tsim khoom yog qhov siab tshaj plaws hardness.Ntxiv rau qhov loj me, cov engineers tseem xav paub meej txog kev tiv thaiv welded (ERW) cov kav dej hauv qhov kev ua haujlwm zoo, uas tuaj yeem ua rau cov duab kos nrog qhov ua tau siab tshaj plaws ntawm HRB 60. Qhov kev txiav txim siab no ib leeg ua rau muaj ntau yam khoom kawg, suav nrog hardness nws tus kheej.
Ua ntej, qhov nyuaj ntawm HRB 60 tsis qhia peb ntau.HRB 60 nyeem ntawv yog tus lej tsis muaj nuj nqis.Cov ntaub ntawv ntsuas ntawm HRB 59 yog softer dua li cov kev sim ntawm HRB 60, thiab HRB 61 nyuaj dua HRB 60, tab sis los ntawm ntau npaum li cas?Nws tsis tuaj yeem suav tau zoo li ntim ( ntsuas hauv decibels), torque ( ntsuas hauv phaus-taw), ceev ( ntsuas hauv qhov deb piv rau lub sijhawm), lossis UTS ( ntsuas hauv phaus ib square inch).Kev nyeem HRB 60 tsis qhia peb ib yam dab tsi tshwj xeeb.Nws yog khoom vaj khoom tsev, tsis yog lub cev khoom.Qhov thib ob, kev txiav txim siab ntawm hardness los ntawm nws tus kheej yog tsis zoo tsim los xyuas kom meej repeatability los yog reproducibility.Kev ntsuam xyuas ntawm ob qhov chaw ntawm ib qho qauv, txawm tias qhov chaw xeem nyob ze ua ke, feem ntau ua rau muaj qhov sib txawv ntawm qhov nyuaj nyeem.Qhov xwm txheej ntawm qhov kev xeem exacerbates qhov teeb meem no.Tom qab ib txoj hauj lwm ntsuas, qhov ntsuas thib ob tsis tuaj yeem coj mus kuaj xyuas qhov tshwm sim.Kev ntsuas rov ua tsis tau.
Qhov no tsis txhais hais tias kev ntsuas hardness tsis yooj yim.Qhov tseeb, qhov no yog ib qho kev qhia zoo rau UTS cov khoom, thiab nws yog qhov kev sim sai thiab yooj yim.Txawm li cas los xij, txhua tus neeg koom nrog hauv kev txhais, kev yuav khoom, thiab kev tsim cov raj yuav tsum paub txog lawv cov kev txwv raws li qhov ntsuas ntsuas.
Vim tias "tsis tu ncua" cov yeeb nkab tsis tau txhais meej meej, cov yeeb nkab cov tuam txhab feem ntau nqaim nws mus rau ob hom kev siv hlau thiab yeeb nkab raws li tau hais tseg hauv ASTM A513: 1008 thiab 1010 thaum tsim nyog.Txawm tias tom qab tsis suav tag nrho lwm hom kav dej, qhov ua tau rau cov khoom siv kho tshuab ntawm ob hom kav dej no tseem qhib.Qhov tseeb, cov kav dej no muaj qhov dav tshaj plaws ntawm txhua yam khoom ntawm txhua hom yeeb nkab.
Piv txwv li, ib lub raj raug suav tias yog mos yog tias MYS yog qhov qis thiab elongation siab, uas txhais tau hais tias nws ua tau zoo dua ntawm kev ncab, deformation, thiab deformation mus tas li tshaj li lub raj tau piav raws li nruj, uas muaj MYS siab thiab kuj tsis tshua muaj elongation. ..Qhov no zoo ib yam li qhov sib txawv ntawm cov hlau mos thiab cov xaim tawv xws li khaub ncaws hangers thiab xyaum xyaum.
Elongation nws tus kheej yog lwm yam uas muaj feem cuam tshuam rau cov yeeb nkab tseem ceeb.High elongation kav yuav tiv taus stretching;Cov ntaub ntawv elongation qis dua yog nkig thiab yog li ntawd ntau dua rau kev puas tsuaj rau kev qaug zog tsis ua haujlwm.Txawm li cas los xij, elongation tsis cuam tshuam ncaj qha rau UTS, uas tsuas yog cov cuab yeej siv tshuab ncaj qha ntsig txog hardness.
Vim li cas cov kav dej sib txawv heev hauv lawv cov khoom siv tshuab?Ua ntej, cov tshuaj muaj pes tsawg leeg sib txawv.Hlau yog ib qho kev daws teeb meem ntawm hlau thiab carbon, nrog rau lwm yam tseem ceeb alloys.Rau kev yooj yim, peb tsuas yog cuam tshuam nrog feem pua ntawm carbon.Cov pa roj carbon atoms hloov qee cov hlau atoms, tsim cov qauv crystalline ntawm cov hlau.ASTM 1008 yog ib qib tseem ceeb nrog cov ntsiab lus carbon ntawm 0% txog 0.10%.Xoom yog tus naj npawb tshwj xeeb uas muab cov khoom tshwj xeeb ntawm cov ntsiab lus ntawm cov pa roj carbon tsawg hauv cov hlau.ASTM 1010 txhais cov ntsiab lus carbon ntawm 0.08% txog 0.13%.Cov kev sib txawv no tsis zoo li loj, tab sis lawv txaus los ua qhov sib txawv loj rau lwm qhov.
Thib ob, cov kav hlau steel tuaj yeem tsim los yog tsim thiab ua tiav hauv xya qhov kev tsim khoom sib txawv.ASTM A513 hais txog kev tsim cov kav dej ERW teev xya hom:
Yog tias cov tshuaj muaj pes tsawg leeg ntawm cov hlau thiab cov theem ntawm cov yeeb nkab tsim tsis cuam tshuam rau hardness ntawm steel, ces dab tsi?Lo lus teb rau lo lus nug no txhais tau hais tias ua tib zoo kawm txog cov ntsiab lus.Lo lus nug no ua rau ob nqe lus nug ntxiv: cov ntsiab lus dab tsi thiab ze li cas?
Cov ncauj lus kom ntxaws txog cov nplej uas ua rau cov hlau yog thawj cov lus teb.Thaum cov hlau yog tsim nyob rau hauv thawj zeb, nws tsis txias rau hauv ib tug loj loj nrog ib tug khoom.Raws li cov hlau txias, nws cov molecules tsim cov qauv rov ua dua tshiab (crystals), zoo ib yam li cov duab snowflakes.Tom qab tsim cov crystals, lawv tau muab tso ua ke rau hauv pawg hu ua nplej.Raws li cov nplej txias, lawv loj tuaj, ua rau tag nrho daim ntawv lossis phaj.Grain loj hlob nres thaum kawg molecule ntawm hlau yog absorbed los ntawm cov nplej.Qhov no txhua yam tshwm sim ntawm qib microscopic, nrog rau qhov nruab nrab-qhov loj me steel nplej yog li 64 microns lossis 0.0025 ntiv tes hla.Txawm hais tias txhua cov nplej zoo ib yam li cov tom ntej, lawv tsis zoo ib yam.Lawv txawv me ntsis los ntawm ib qho loj, kev taw qhia, thiab cov ntsiab lus carbon.Cov kev sib tshuam ntawm cov nplej yog hu ua grain ciam teb.Thaum cov hlau tsis ua haujlwm, piv txwv li vim qaug zog tawg, nws zoo li ua tsis tiav ntawm cov ciam teb.
Koj yuav tsum saib ze npaum li cas kom pom cov khoom sib txawv?Kev nthuav dav ntawm 100 npaug lossis 100 npaug ntawm qhov pom kev pom ntawm tib neeg lub qhov muag yog txaus.Txawm li cas los xij, tsuas yog saib cov hlau nyoos mus rau 100 lub zog tsis ua ntau.Cov qauv yog npaj los ntawm polishing tus qauv thiab etching nto nrog cov kua qaub, feem ntau yog nitric acid thiab cawv, uas yog hu ua nitric acid etching.
Nws yog cov nplej thiab lawv cov lattice sab hauv uas txiav txim siab qhov cuam tshuam lub zog, MYS, UTS, thiab elongation uas cov hlau tuaj yeem tiv taus ua ntej tsis ua haujlwm.
Steelmaking cov kauj ruam xws li kub thiab txias strip dov hloov kev ntxhov siab rau cov qauv lis;yog tias lawv hloov pauv tas li, qhov no txhais tau hais tias kev ntxhov siab tau deformed cov nplej.Lwm cov kauj ruam ua xws li winding cov hlau rau hauv coils, unwinding thiab dhau los ntawm ib lub raj zeb (los tsim lub raj thiab loj) deform cov hlau nplej.Kev kos duab txias ntawm cov yeeb nkab rau ntawm lub mandrel kuj tseem ceeb rau cov khoom siv, xws li cov txheej txheem tsim khoom xws li qhov kawg sib sau thiab khoov.Kev hloov pauv hauv cov qauv nplej yog hu ua dislocations.
Cov kauj ruam saum toj no deplete cov hlau ductility, nws muaj peev xwm tiv taus tensile (tearing) kev ntxhov siab.Hlau ua nkig, uas txhais tau hais tias nws yuav tawg yog tias koj txuas ntxiv ua haujlwm nrog cov hlau.Elongation yog ib feem ntawm plasticity (compressibility yog lwm qhov).Nws yog ib qho tseem ceeb kom nkag siab qhov no tias qhov tsis ua haujlwm feem ntau tshwm sim hauv kev nro, thiab tsis yog hauv compression.Steel yog heev resistant rau tensile stresses vim nws kuj siab elongation.Txawm li cas los xij, steel yooj yim deforms nyob rau hauv compressive kev nyuaj siab - nws yog malleable - uas yog ib qho zoo dua.
Muab piv rau qhov no rau pob zeb, uas muaj zog compressive heev tab sis tsis muaj ductility.Cov khoom no yog opposite rau hlau.Qhov no yog vim li cas pob zeb siv rau txoj kev, cov tsev thiab cov kev taug kev yog feem ntau ntxiv dag zog.Qhov tshwm sim yog cov khoom lag luam uas muaj lub zog ntawm ob qho khoom siv: steel muaj zog hauv qhov nro thiab pob zeb muaj zog hauv compression.
Thaum lub sij hawm hardening, lub ductility ntawm steel txo, thiab nws hardness nce.Hauv lwm lo lus, nws hardens.Nyob ntawm qhov xwm txheej, qhov no tuaj yeem yog qhov zoo dua, tab sis nws kuj tuaj yeem ua rau muaj qhov tsis zoo, vim tias hardness sib npaug rau brittleness.Qhov ntawd yog, qhov nyuaj ntawm cov hlau, qhov tsawg elastic nws yog thiab yog li nws yuav ua tsis tau.
Hauv lwm lo lus, txhua kauj ruam ntawm cov txheej txheem yuav tsum muaj qee cov yeeb nkab ductility.Raws li ib feem yog ua tiav, nws yuav hnyav dua, thiab yog hais tias nws hnyav dhau lawm, ces nyob rau hauv txoj cai nws yog tsis siv.Hardness yog brittleness, thiab brittle tubes yog feem ntau ua rau tsis ua hauj lwm thaum siv.
Cov chaw tsim khoom puas muaj kev xaiv hauv qhov no?Hauv luv, yog.Qhov kev xaiv no yog annealing, thiab thaum tsis raws nraim tej yam yees siv, nws yog hais txog tej yam yees siv li yuav ua tau.
Hauv cov ntsiab lus yooj yim, annealing tshem tawm tag nrho cov teebmeem ntawm lub cev cuam tshuam rau cov hlau.Nyob rau hauv tus txheej txheem, cov hlau yog rhuab mus rau ib tug kev nyuaj siab nyem los yog recrystallization kub, uas ua rau tshem tawm ntawm dislocations.Yog li, cov txheej txheem ib nrab los yog tag nrho rov ductility, nyob ntawm seb qhov kub thiab lub sij hawm siv nyob rau hauv cov txheej txheem annealing.
Annealing thiab tswj cua txias txhawb kev loj hlob ntawm grain.Qhov no tau txais txiaj ntsig yog tias lub hom phiaj yog txhawm rau txo qhov brittleness ntawm cov khoom siv, tab sis tsis muaj kev tswj hwm kev loj hlob tuaj yeem ua rau cov hlau muag ntau dhau, ua rau nws siv tsis tau rau nws txoj kev npaj siv.Kev txwv tsis pub cov txheej txheem annealing yog lwm yam yuav luag zoo nkauj.Quenching ntawm qhov kub thiab txias nrog tus neeg sawv cev zoo ntawm lub sijhawm sai sai nres cov txheej txheem thiab rov ua kom cov khoom ntawm cov hlau.
Peb yuav tsum tso tseg hardness specifications?tsis muaj.Cov khoom ntawm hardness yog qhov tseem ceeb, ua ntej ntawm tag nrho cov, raws li cov lus qhia hauv kev txiav txim siab cov yam ntxwv ntawm cov kav hlau steel.Hardness yog ib qho kev ntsuas muaj txiaj ntsig thiab ib qho ntawm ntau yam khoom uas yuav tsum tau teev tseg thaum xaj cov khoom siv tubular thiab kuaj xyuas thaum tau txais (cov ntaub ntawv rau txhua qhov khoom xa tuaj).Thaum lub hardness xeem yog siv raws li tus qauv xeem, nws yuav tsum muaj qhov tsim nyog teev qhov tseem ceeb thiab tswj kev txwv.
Txawm li cas los xij, qhov no tsis yog qhov tseeb ntawm kev dhau (kev lees paub lossis tsis lees paub) ntawm cov khoom.Ntxiv nrog rau qhov tawv tawv, cov tuam txhab tsim khoom yuav tsum kuaj xyuas cov khoom xa tuaj ib ntus los txiav txim siab lwm yam khoom siv xws li MYS, UTS, lossis qhov tsawg kawg nkaus elongation, nyob ntawm daim ntawv thov yeeb nkab.
Wynn H. Kearns is responsible for regional sales for Indiana Tube Corp., 2100 Lexington Road, Evansville, IN 47720, 812-424-9028, wkearns@indianatube.com, www.indianatube.com.
Tube & Pipe Journal tau tsim tawm hauv xyoo 1990 ua thawj phau ntawv xov xwm tshwj xeeb rau kev lag luam yeeb nkab hlau.Niaj hnub no, nws tseem tsuas yog kev lag luam luam tawm hauv North America thiab tau dhau los ua cov ntaub ntawv ntseeg siab tshaj plaws rau cov kws tshaj lij tubing.
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Hauv qhov thib ob ntawm peb qhov kev qhia ob ntu nrog Adam Heffner, Nashville tus tswv khw thiab tus tsim…
Post lub sij hawm: Jan-27-2023