Brazing ntawm cov cuab yeej steel thiab cemented carbide

1. Cov khoom siv brazing

(1) Brazing cuab yeej steels thiab cemented carbides feem ntau siv tooj liab ntshiab, tooj liab zinc thiab nyiaj tooj liab brazing muab tub lim hlau. Ntshiab tooj liab muaj zoo wettability rau tag nrho cov hom ntawm cemented carbides, tab sis qhov zoo tshaj plaws nyhuv yuav tau los ntawm brazing nyob rau hauv txo qhov cua ntawm hydrogen. Nyob rau tib lub sijhawm, vim qhov kub siab brazing, qhov kev ntxhov siab hauv kev sib koom ua ke yog loj, uas ua rau muaj kev nce ntawm kev sib tsoo. Lub zog shear ntawm qhov sib koom ua ke nrog cov tooj liab ntshiab yog li 150MPa, thiab cov yas sib koom ua ke kuj siab, tab sis nws tsis haum rau kev ua haujlwm kub.

Copper zinc muab tub lim hlau yog cov khoom siv feem ntau siv rau cov cuab yeej brazing steels thiab cemented carbides. Txhawm rau txhim kho lub wettability ntawm solder thiab lub zog ntawm kev sib koom ua ke, Mn, Ni, Fe thiab lwm yam hlau alloy feem ntau tau ntxiv rau cov khoom siv. Piv txwv li, w (MN) 4% yog ntxiv rau b-cu58znmn kom lub zog shear ntawm cemented carbide brazed pob qij txha ncav cuag 300 ~ 320MPa ntawm chav tsev kub; Nws tseem tuaj yeem tswj tau 220 ~ 240mpa ntawm 320 ℃. Ntxiv ib qho me me ntawm CO raws li lub hauv paus ntawm b-cu58znmn tuaj yeem ua rau lub zog shear ntawm lub brazed sib koom ua ke mus txog 350Mpa, thiab muaj kev cuam tshuam siab tawv thiab qaug zog, txhim kho lub neej kev pab cuam ntawm cov cuab yeej txiav thiab cov cuab yeej pob zeb drilling.

Qhov qis melting point ntawm nyiaj tooj liab brazing muab tub lim hlau thiab me me thermal kev nyuaj siab ntawm brazed sib koom ua ke tau zoo los txo cov kev sib tsoo ntawm cemented carbide thaum lub sij hawm brazing. Txhawm rau txhim kho lub wettability ntawm lub solder thiab txhim kho lub zog thiab ua haujlwm kub ntawm qhov sib koom ua ke, Mn, Ni thiab lwm yam hlau alloy feem ntau tau ntxiv rau cov khoom siv. Piv txwv li, b-ag50cuzncdni solder muaj wettability zoo heev rau cemented carbide, thiab cov brazed sib koom ua ke muaj cov khoom zoo.

Ntxiv rau cov saum toj no peb hom brazing muab tub lim hlau, Mn raws li thiab Ni raws li brazing muab tub lim hlau, xws li b-mn50nicucrco thiab b-ni75crsib, tuaj yeem xaiv rau cemented carbide ua haujlwm siab tshaj 500 ℃ thiab xav tau kev sib koom tes siab. Rau lub brazing ntawm high-speed steel, tshwj xeeb brazing muab tub lim hlau nrog lub brazing kub sib piv cov quenching kub yuav tsum tau xaiv. Cov hlau muab tub lim no tau muab faib ua ob pawg: ib qho yog ferromanganese hom muab tub lim hlau, uas yog tsim los ntawm ferromanganese thiab borax. Lub zog shear ntawm lub brazed sib koom yog feem ntau txog 100MPa, tab sis qhov sib koom ua ke yog qhov ua rau tawg; Lwm hom tshwj xeeb tooj liab alloy muaj Ni, Fe, Mn thiab Si tsis yooj yim los tsim cov kab nrib pleb hauv cov pob qij txha, thiab nws lub zog shear tuaj yeem nce mus txog 300mpa.

(2) Kev xaiv ntawm brazing flux thiab shielding gas brazing flux yuav tsum sib phim nrog lub hauv paus hlau thiab muab tub lim hlau yuav tsum tau welded. Thaum brazing cuab yeej steel thiab cemented carbide, lub brazing flux siv mas yog borax thiab boric acid, thiab ib co fluorides (KF, NaF, CaF2, thiab lwm yam) ntxiv. Fb301, fb302 thiab fb105 fluxes yog siv rau tooj liab zinc solder, thiab fb101 ~ fb104 fluxes yog siv rau nyiaj tooj liab solder. Borax flux yog tsuas yog siv thaum tshwj xeeb brazing muab tub lim hlau yog siv los braze high-speed steel.

Txhawm rau tiv thaiv oxidation ntawm cov cuab yeej hlau thaum lub sij hawm brazing cua sov thiab kom tsis txhob ntxuav tom qab brazing, roj shielded brazing yuav siv tau. Cov roj tiv thaiv tuaj yeem yog cov roj tsis muaj zog lossis txo cov roj, thiab cov dej lwg ntawm cov roj yuav tsum qis dua -40 ℃ Cemented carbide tuaj yeem ua tau raws li kev tiv thaiv hydrogen, thiab cov dej lwg taw tes ntawm hydrogen yuav tsum qis dua -59 ℃.

2. Brazing tshuab

Cov cuab yeej hlau yuav tsum tau muab ntxuav ua ntej brazing, thiab lub tshuab nto yuav tsum tsis txhob du dhau los ua kom yooj yim rau cov ntaub ntub dej thiab sib kis ntawm cov ntaub ntawv thiab cov khoom siv brazing. Qhov saum npoo ntawm cemented carbide yuav tsum tau xuab zeb blasted ua ntej brazing, los yog polished nrog silicon carbide los yog pob zeb diamond sib tsoo log kom tshem tawm cov pa roj carbon ntau dhau ntawm qhov chaw, thiaj li yuav tsum tau wetted los ntawm brazing muab tub lim hlau thaum lub sij hawm brazing. Cemented carbide uas muaj titanium carbide yog qhov nyuaj rau ntub. Copper oxide los yog npib tsib xee oxide muab tshuaj txhuam yog siv rau ntawm nws qhov chaw nyob rau hauv ib txoj kev tshiab thiab ci nyob rau hauv ib tug txo qhov cua kom tooj liab los yog npib tsib xee hloov mus rau saum npoo, thiaj li ua rau kom lub wettability ntawm muaj zog solder.

Lub brazing ntawm cov cuab yeej carbon steel yuav tsum zoo dua ua ntej los yog tib lub sij hawm raws li cov txheej txheem quenching. Yog tias brazing tau ua ua ntej cov txheej txheem quenching, qhov kub ntawm cov khoom siv hlau siv yuav tsum siab dua qhov kub ntawm qhov sib txawv, yog li cov vuam tseem muaj lub zog txaus thaum rov ua kom sov rau qhov kub thiab txias yam tsis muaj kev ua haujlwm. Thaum brazing thiab quenching yog ua ke, cov hlau muab tub lim nrog solidus kub ze rau quenching kub yuav tsum raug xaiv.

Alloy cuab yeej steel muaj ntau yam ntawm cov khoom. Tsim nyog brazing muab tub lim hlau, txheej txheem kev kho cua sov thiab cov thev naus laus zis ntawm kev sib txuas ntawm brazing thiab cov txheej txheem kho cua sov yuav tsum tau txiav txim siab raws li hom steel tshwj xeeb, kom tau txais kev sib koom ua haujlwm zoo.

Lub quenching kub ntawm high-speed steel feem ntau siab tshaj qhov kub ntawm cov nyiaj tooj liab thiab tooj liab zinc solder, yog li nws yuav tsum tau quench ua ntej brazing thiab braze thaum lub sij hawm los yog tom qab tempering. Yog tias yuav tsum tau quenching tom qab brazing, tsuas yog cov saum toj no-hais tshwj xeeb brazing muab tub lim hlau tuaj yeem siv rau brazing. Thaum brazing high-speed steel txiav cov cuab yeej, nws tsim nyog siv coke rauv. Thaum lub brazing muab tub lim hlau yog melted, tshem tawm cov cuab yeej txiav thiab tam sim ntawd pressurize nws, extrude lub ntau tshaj brazing muab tub lim hlau, ces nqa tawm roj quenching, thiab ces temper nws ntawm 550 ~ 570 ℃.

Thaum brazing cov cemented carbide hniav nrog cov cuab yeej steel bar, txoj kev nce qhov sib txawv ntawm qhov sib txawv thiab siv cov khoom siv yas rau hauv qhov sib txawv ntawm lub brazing yuav tsum tau txais, thiab kev ua kom txias qeeb yuav tsum tau nqa tawm tom qab vuam kom txo qis brazing kev nyuaj siab, tiv thaiv cov kab nrib pleb thiab ua kom lub neej ntev ntawm cov cemented carbide cov cuab yeej sib dhos.

Tom qab fiber ntau welding, cov flux residue ntawm lub vuam yuav tsum tau ntxuav nrog dej kub los yog cov slag tshem tawm cov sib tov, thiab ces pickled nrog tsim nyog pickling tov kom tshem tawm cov oxide zaj duab xis ntawm lub hauv paus cuab yeej pas nrig. Txawm li cas los xij, ceev faj tsis txhob siv cov tshuaj nitric acid los tiv thaiv corrosion ntawm brazing sib koom hlau.