Dacromet-Coated Bolts thiab ceev

Xyoo 2026-10-28

1. Taw qhia

Kev sib txuas threaded tsuas yog muaj zog raws li nws qhov tsis muaj zog tshaj plaws. Tus hwm Dacromet-coated hex bolt torqued rau hauv cov txiv ntoo pheej yig zinc-plated tsis yog kev tiv thaiv corrosion - nws yog galvanic cell tos tsis tau. Cov txiv ntoo zinc-plated ua cov anode nyob rau hauv ob peb, corrodes preferentially, seizes ntawm lub bolt threads, thiab tag nrho cov kev sib koom ua ke poob nws clamp load ntev ua ntej lub bolt nws tus kheej qhia cov liab xeb.

Vim li no, kev fastener specifications ib txwm kho bolts, txiv ntseej thiab cov ntxhua khaub ncaws ua ib pob khoom tiv thaiv corrosion. Dacromet (zinc-aluminium flake, non-electrolytic) txheej yog cov txheej txheem ntawm kev xaiv rau pob ntawv no: nws muab txhua txoj xov - txiv neej thiab poj niam - nyias (5-12 μm), sib xws, tsis muaj hydrogen zaj duab xis uas tiv taus 500-1,000 teev ntawm nruab nrab ntsev tsuag (NSS) raug tsis muaj xeb dawb los yog xeb liab.

Kab lus no piav qhia txog cov tsev neeg fastener koom nrog, cov txheej txheem corrosion uas tawm tsam threaded pob qij txha, vim li cas Dacromet suits bolts thiab txiv ntseej ib yam nkaus, thiab yuav ua li cas qhia thiab sib sau ua ke bolt-nut-washer teeb.

2. Yuav Ua Li Cas Corrosion Attacks Ib Threaded Joint

Cov xov yog qhov feem ntau corrosion-vulnerable geometry ntawm ib qho kev sib dhos fastener:

1.Crevice corrosion- lub microscopic qhov sib txawv ntawm bolt xov flank thiab txiv ntseej xov flank ntxiab ya raws thiab electrolyte, tsim kom muaj oxygen tshaib plab crevice qhov chaw anodic tsim thiab pitting pib;

2. Galvanic corrosion- cov txheej txheem sib txawv los yog hlau (dacromet ntsia liaj qhov rooj nrog cov txiv ntseej electro-plated, stainless bolt hauv cov txiv ntoo galvanized) tsav qhov kev nyiam ntawm cov khoom tsis zoo;

3.Coating kev puas tsuaj ntawm kev sib dhos- threads scrape thiab gall thaum zawm; nyias electroplate thiab organic xim yog yooj yim txiav los ntawm, exposing liab qab hlau nyob rau hauv xov cov hauv paus hniav;

4.Stress concentration- thawj cov kabmob cov kabmob muaj qhov tsis sib xws ntawm kev thauj khoom ua ntej, yog li corrosion pits muaj sai ua rau qaug zog tawg;

5.Fretting nyob rau hauv vibration- micro txav ntawm cov kabmob ntsej muag abrades zaj duab xis, caw dawb xeb thiab tom qab ntawd xeb liab.

Thaum cov khoom siv xeb tsim nyob rau hauv cov xov, cov txiv ntseej txeeb tau, lub zog tawg ntau tshaj qhov kev teeb tsa lub zog, thiab cov ntsia liaj qhov rooj lossis cov ntsia hlau feem ntau yuav tsum tau txiav tawm - classic "frozen txiv ntoo" tsis ua haujlwm hauv kev saib xyuas.

3. Corrosion Resistance ntawm Matched Set

Txheej txheej (bolt + txiv ntseej + ntxhua khaub ncaws)	Thickness	NSS rau liab xeb	Xov haum tom qab txheej	Hydrogen embrittlement	Tus nqi txheeb ze
Plain / tus kheej xim, oiled	—	<24 h	Zoo heev	Tsis muaj	qis tshaj
Zinc phaj + xiav chromate	5m ua	≈ 48 h	Zoo	Siab	Tsawg
Zinc phaj + tuab tri-passivate	8-12 m	120-240 hnub	Zoo	Siab	Tsawg- nruab nrab
Mechanical galvanizing	20-50 m	300-800 hnub	Zoo	Tsawg heev	Nruab nrab
Kub-dip galvanizing (txiv ntseej rov tapping)	45-85 hli	500-1,500 h	Re-tapping xav tau	Tsawg	Nruab nrab
Dacromet Chav Kawm 2 (flZn 8)	8m ua	≈ 720 h	Zoo heev	Tsis muaj	Nruab nrab
Dacromet Class 3 / dub	10-12 m	≈ 1,000 h	Zoo heev	Tsis muaj	Nruab nrab-siab

Table 1. Txheej txheej rau bolt-nut sib dhos piv (tus nqi kev lag luam ib txwm).

Vim tias cov txheej txheem siv los ua kom tiav, cov khoom siv kho cua sov thiab kho tau qis dua qhov kub thiab txias, ob qho tib si bolts thiab txiv ntseej khaws lawv cov khoom siv tag nrho - lub zog tensile, pov thawj load thiab hardness ntawm ISO 898-1 / ISO 898-2 - tsis hloov.

4. Sib dhos zoo tshaj plaws

1.Tsis txhob sib tov txheej txheej- khub Dacromet bolts tsuas yog nrog Dacromet ceev thiab ntxhua khaub ncaws; ib tug sib tov ob peb tsav galvanic corrosion ntawm cov tsis muaj zog (feem ntau zinc-plated) ib feem;

2.Saib lub rooj torque- lubricated Dacromet khub muaj qis dua, ruaj khov txiv ntoo zoo dua li cov hlau liab qab; reusing qub torque qhov tseem ceeb tshaj-tightens thiab yuav strip lub txiv ntseej threads;

3.Tsis txhob rov lubricate- kev sib xyaw topcoat twb teev cov kev sib txhuam coefficient; ntxiv roj ntawm threads hloov K unpredictably;

4.Mind lub jam-txiv ntoo txiav txim- thaum cov txiv ntseej nyias thiab cov txiv ntseej tag nrho tau muab tso ua ke (classic locking arrangement), ceev cov txiv ntseej tag nrho tiv thaiv cov txiv ntoo nyias;

5.Saib kom khausntawm cov khub stainless - Dacromet's lubricant topcoat kuj txo qis kev pheej hmoo ntawm cov pob txha stainless;

6.Tshuaj xyuas thawj kab lus torque-nrujnyob rau hauv kev sim skid, siv qhov tseeb bolt-nut-washer ua ke los ntawm ntau lawm.

5. Xaus

Corrosion tsis ua hauj lwm tsis tshua muaj pib ntawm lub shank ntawm lub ntsia liaj qhov rooj - nws pib nyob rau hauv cov xov, nyob rau hauv lub crevice ntawm lub bolt thiab txiv ntseej. Kev sib koom tes ruaj khov yog li xav tau a matched corrosion-tiv thaiv pob: Dacromet-coated bolts, ceev thiab ntxhua hauv tib lub zinc-flake system, teev ua ke (ISO 10683 / ASTM F1136, flZn 8/10, ≥ 720 h NSS), sib sau ua ke nrog qhov tseeb torque thiab kev sib txhuam qhov tseem ceeb. Qhov tshwm sim yog ib qho kev sib txuas uas tiv thaiv xeb dawb, xeb liab, pitting, crevice nres thiab qaug dab peg - dhau xyoo ntawm ntsev tsuag, huab cua thiab kev co.

Ua ntej. Tom ntej no.

Xov xwm tshiab