Soláthraíonn bratuithe galbhánaithe tumtha te cosaint chreimthe den scoth don tsubstráit chruach, ach ní bhíonn a chríochnú i gcónaí réidh nó aonfhoirmeach.péinteáil, sciath púdarnósherardizing. Go ginearálta, tá tiús sciath since sonraithe ag cótaí ghalbhánuithe le haghaidh friotaíocht creimeadh, agus níl sé sonraithe ag a chuma. Mar sin féin, is féidir leis an gceannaitheoir a shonrú i gcónaí cad iad na láithrithe neamhdheimhnitheacha, agus seo thíos na samplaí tipiciúla.
1. Slag Spatters Táthú
Is fearr modhanna táthúcháin nach dtáirgeann slaig, mar tháthú MIG. Má úsáidtear leictreoidí táthú brataithe, ba cheart gach taisce slaig a bhaint go cúramach ón weld. Ní féidir slaig táthúcháin a bhaint trí ghnáthphicling, agus cruthaíonn aon iarmhar spotaí dubha le linn galbhánú-tumtha te. Bainfear spásairí táthú, slaig agus phiocháin i gcónaí sula gcuirtear tús le réamhchóireáil galbhánaithe, ar shlí eile beidh cuma an-gharbh ar dhromchla an ghalbhánuithe.
2. Gaiste Aigéad
Steel structures should be designed to avoid narrow crevices or gaps. If lap welds must be used, they should be welded around the entire joint. In case of double-sided fillet welds, the weld must be continued over the ends of the steel material to prevent the penetration of acid into any conceivable crevice. Plus, it is important to avoid the formation of pinholes. If the gap between contact surfaces is larger than 100 cm², venting holes must be provided to avoid the risk of explosion. Since molten zinc is more viscous than acid, it will seal the opening during hot-dip galvanizing. Afterwards, the acid will create holes in the coating, and then the rust-colored liquid will run on to the surface and spoils the appearance. Therefore, once acid has penetrated a crevice, it is impossible to be removed.
3.Drainage Spikes
Drainage spike is a very common defect, and it can be greatly avoided by setting up a hanging angle close to 45 degree ,which can minimize drainage at the bottom of the workpiece. Hanging steel works with a horizontal angle is forbidden, which will cause excessive drainage spikes. Grinding of drainage spikes shall be handled carefully, and overgrinding shall be prohibited.
Pimples 4.Dross
Dross pimples are small zinc-iron crystals formed from iron reacting with molten zinc during galvanization process. Dresses are heavier than zinc, and they settle on the bottom of the zinc kettle where they are periodically removed every 2 weeks or 10days. If the dross is stirred up and mixed into the molten zinc, it will often get trapped in the zinc coating leaving marks like pimples on the galvanization surface. An excessive amount of pimples can indicate a poor coating, and the zinc kettle shall be cleaned soon before another shift starts.
5.Ash staining
Sometimes, ash is trapped inside areas and sticks to the outer side of the coating as the steelwork is lifted from the zinc bath. Ash may cause a light brown stain, a dull or dark surface appearance after removal. It has negative impact upon the performance of the galvanized coating, and it's possible to be repaired by zinc paint if its size is small.
6.Striations, cnapáin agus Rith
Is iad na hiomairí agus na línte atá níos tiús ná an sciath ghalbhánuithe in aice láimhe is cúis le rátaí éagsúla imoibrithe an since leis an dromchla cruach mar gheall ar limistéir struis ar an dromchla cruach nó láithreacht limistéir táthaithe nó táthú miotail le miotalóireacht athraithe don mháthairmhiotal. Is minic a fheictear an teagmhas seo ar fheadáin chruach agusrolla déanta próifílí cruach. There is no impact on coating performance, but it does have appearance issue. Please also be reminded that it's a bad practice to remove the lumps by angle grinder vigorously, and this could remove the whole zinc coating leaving the steel uncoated.
7.Marcanna Crochta
Hanging marks are almost impossible to avoid, but it's possible to adjust the hanging angle to minimize the hanging marks. And, it's also possible to use manual grinder to remove marks with care, and then repair them by zinc rich paint.
8.Galbhánú Sleá
Flaking is the separation of the entire zinc coating, including the iron zinc alloy layers from the underlying steel. It is also known as delamination or chipping and should not be confused with peeling where only the top pure zinc layer separates from the underlying zinc alloy layers. Flaking usually occurs in thicker than normal galvanized coatings (200 μm or more), especially when these coatings receive impact forces during handling. Excessively thick coatings generate high stresses at the interface of the steel and galvanized coating which causes the zinc to become flaky and separate from the steel surface. Flaking typically occurs near the edges and creates bare spots in the protective zinc coating and it should be repaired to ensure ongoing corrosion protection. If the area of flaking is small, it can be repaired; however, if the flaking area is larger than allowed by the specifications, the part must be rejected and re-galvanized. Flaking can be avoided by minimizing the immersion time in the galvanizing kettle and cooling of the galvanized steel parts as quickly as possible, and if possible using a different steel grade. Steels with phosphorous content greater than 0.025 percent can experience flaking after galvanizing, even when the silicon levels are satisfactory.
9. Peeling agus Delamination
Delamination or peeling creates a rough coating on the steel where the zinc comes off. Many large galvanized structures and steel profiles take a long time to cool in the air, and the zinc coating continues to form zinc-iron layer after they have been lifted from the zinc bath. This continued coating formation leaves a gap between the top two layers of the galvanized coating. If there are many gaps formed, the top layer of zinc can separate from the rest of the coating and peel off the part. If the remaining coating still meets the minimum specification requirements, then the part is acceptable. If the zinc coating that remains on the steel does not meet the minimum specification requirements, then the part must be rejected and re-galvanized.
Spotaí 10.Bare
Is locht dromchla iad spotaí lom, limistéir neamhbhrataithe ar an dromchla cruach, a d'fhéadfadh tarlú mar gheall ar ullmhú dromchla neamhleor. D’fhéadfadh spotaí lom a bheith mar thoradh ar slaig táthú, gaineamh atá leabaithe i teilgin, ró-alúmanam sa chiteal galbhánaithe, nó gléasanna ardaithe a chuireann cosc ar an sciath a fhoirmiú i limistéar beag. D'fhonn spotaí lom a sheachaint, ní mór don ghalbhánóir a chinntiú go bhfuil na dromchlaí glan agus gan meirge tar éis pretreatment. Is féidir spotaí beaga lom a dheisiú le spraeáil saibhir since. Má tá méid an láthair lom nó líon iomlán na spotaí os cionn na gceanglas a shonraítear le ISO 1461, caithfidh an workpiece cruach dul tríd an réamhchóireáil iomlán agus an galbhánú arís.
11.Mottling
A mottled surface appearance is caused by uneven cooling rates of newly hot-dip galvanized articles after withdrawal from the zinc bath. During air cooling of the articles, the zinc-iron coating formation reaction, consuming the outer free zinc layer in the process, can continue for a short time as long as the steel stays about 550 Fahrenheit degree. Due to the fact that the galvanizing reaction continues on the interior portion and consumes the free zinc layer, but not the exterior potion of the steel, and this causes a nonuniform appearance of the zinc coating. However, this difference in appearance does not affect the corrosion protection of the galvanized coating, and this mottling surface is acceptable per ISO 1461 specifications. Therefore, to speed up the cooling process, quenching is recommended. But, the galvanizers shall be reminded that some designs might not be suitable for quenching as they have a tendency for warpage or distortion during quenching process.
After galvanizing, the steel cools from a temperature of approximately 840 F to ambient temperature. If the steel is quenched, cooling takes place rapidly, but not all galvanizers have quench baths and quenching is not recommended on some designs due to the potential for warpage/distortion of the steel. When the newly galvanized steel is allowed to cool naturally (without quenching), it can take several hours for the steel to come down to ambient temperature. Thinner steel cools faster while thicker steel takes longer to cool. Sometimes an individual piece of steel will have different cooling rates.
Críochnaigh 12.Dull
The most common reason for dull appearances is the chemistry of the workpiece, and the main elements of steel chemistry which most strongly influence the final appearance are silicon and phosphorous. Both elements are catalysts to coating growth, and the thicker coating is responsible for the differing appearance. In addition to producing thicker coatings, highly reactive steels tend to have a matte gray or mottled appearance instead of a typical bright coating.
Deisiúchán 13.Poor Galbhánú
Tá obair dheisiúcháin ghalbhánuithe chomh tábhachtach ar bhealach éigin leis an obair ghalbhánuithe féin, agus is beag botúin choitianta a sheachnófar.
√ Overgrinding, removed the zinc coating completely
√ Ag baint úsáide as spraeire cion íseal since a dheisiú
√ Ní chomhlíonann tiús deisiúcháin since an tiús riachtanach
Tá dian-rialú próiseas táirgthe i bhfeidhm ag Fabmann clúdachcóireáil dromchla miotail, agus tá an-taithí againn ar innealtóirí cáilíochta a bhfuil eolas domhain acu maidir le réamhchóireáil galbhánú te, galbhánú agus deisiú galbhánú. Sin an fáth gur féidir linn cáilíocht préimhe a sholáthar do raon leathan táirgí cruach marcrua-earraí lúibín duga, racaí saincheaptha, lúibíní uillinn threisithe, rolla déanta próifílí cruach, lúibíní comhartha poistaguslúibíní cage le haghaidh feirmeoireacht éisc to our clients.
