CN1192120C - Technology for hot-dipping 5% Al-Zn alloy on iron or steel - Google Patents
Technology for hot-dipping 5% Al-Zn alloy on iron or steel Download PDFInfo
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Abstract
The present invention relates to a method for plating 5% Al-Zn alloy on a surface of steel or iron by dipping, which comprises steps: hot dipping galvanizing treatment, treatment of reducing plating thickness and hot dipping plating operation of 5% Al-Zn alloy, and a plating with long residual action is formed on the surface of steel or iron. A majority of the 5% Al-Zn alloy plating formed on the surface of steel or iron by the method is in a eutectic structure, a dielectric metallic layer with a Fe-Zn-Al ternary structure is formed at an interface, the anticorrosive function and the good mechanical properties of the steel or iron are considerably improved, and the plating is a good film.
Description
The invention relates to the technology of hot dip aluminum plating zn alloy coating on iron and steel, after especially handling, utilize thickness of coating to reduce and handle and hot dip process 5%Al-Zn alloy, to make the long-lasting corrosion protection iron and steel of tool 5%Al-Zn alloy layer about galvanizing.
Galvanizing has to the corrosion protection time limit of steel structure thing in general atmospheric environment that it is economical and long-lasting, and not outer two kinds of the protection mechanisms that pure zinc coating provides the iron and steel ground: the generation of first oxide compound epithelium can intercept corrosion factor and continue to invade ground; It two promptly is that the sacrificial anode effect of zinc replaces the ground corrosion.
Yet as salt damage area, industrial gaseous waste, and humid area etc., its anti-corrosion time limit of steel structure thing of galvanizing reduces sharply to general geographic below 1/5th in special corrosive environment.For in high density salt damage district and the steel structure thing of obnoxious flavour corrosion region, the long-lasting coating of exploitation tool is real to be epochmaking problem.
Industrial other kinds coating arranged still, for example hot dip aluminum plating is an example.And hot dip aluminum plating main purpose, be that aluminium coated easily generates the very strong oxide film of slushing oil, especially in the atmosphere of moist thermal environment, high salt zone or sulfur compound, can find out that more its effect is better than galvanizing.Yet, hot dip aluminum plating disadvantage be that the sacrificial anode effect is poor, therefore slight crack appears when coating, corrosion takes place, the oxide film function is had a greatly reduced quality, even loss of function.
In addition, general industry circle can add γ phase iron-zinc alloy layer that a spot of aluminium is eliminated zinc-iron interface in pure zinc coating, make plating piece have more processibility.Because the aluminium that adds seldom, do not influence the anti-corrosion performance of coating, effect in that brittle γ phase iron-zinc alloy layer is disappeared, is all to be confined to zinc-iron at the interface with its distribution only.
Find in galvanizing coating, to add the corrosion protection ability that the aluminium of volume slightly can be promoted coating subsequently, in the Al-Zn of various ratios combination, after academia and industry member are considered one integration of do on coating function and the practice, the coating that discovery is allocated with 5%Al-Zn has the corrosion protection speciality of pure zinc and fine aluminium coating concurrently, the practice of the economic material benefit of can yet be regarded as.Especially at the general atmosphere environment or contain in salt, the sulfide environment, more can highlight the resistance to corrosion of this coating excellence.
The coating of 5%Al-Zn is in response to this demand and produces.For being in all the year round in high temperature, high humidity, the environment high in salt, such as Taiwan is positioned at subtropics and seagirt, and the etching problem of iron and steel object is quite serious.Particularly area and marine drilling platform by the sea, general galvanizing steel part has not met demand, and can prolong steel part life-span and increase its corrosion stability if change the 5%Al-Zn coating that adopt to add small amount of aluminum this moment.
So since nineteen eighty-three 5%Al-Zn commercialization commodity " Galfan " were released, academia and industry member once dropped into the research of 5%Al-Zn coating energetically.Yet in the research in the past, be confined to laboratory scale immersion technique always, fail to reach the practical standard of volume production all the time.With regard to the processing procedure of commodity Galfan, it also rests in the application of steel plate (sheet) and coil of strip (coil) always, fails technically to break through for crowd formula hot dipping (batch-type hot-dip) 5%Al-Zn always; The present invention has then overcome the problems referred to above and has successfully developed the immersion technique of 5%Al-Zn coating volume production scale, and the immersion technique of the present invention's exploitation is not limited to steel plate and coil of strip, little to bolt, nut and greatly to various steel structure things such as girder steels, can successfully obtain the 5%Al-Zn coating of fine texture.
The object of the present invention is to provide a kind of method of iron and steel hot dip process 5%Al-Zn alloy, be included between galvanizing and hot dip process 5%Al-Zn alloy two steps and reduce processing, and obtain to have the iron and steel of long-lasting corrosion protection coating with thickness of coating.
Another object of the present invention is to provide a kind of method that batch formula and continous way are carried out iron and steel hot dip process 5%Al-Zn alloy that is suitable for, it can form the 5%Al-Zn alloy layer on various steel structure thing, and reaches the practical scale of volume production.
A further object of the present invention is to provide a kind of iron and steel structure thing of the 5%Al-Zn of containing alloy layer, and preferable resistance to corrosion of its tool and excellent mechanical properties are applicable to the iron and steel object product of various demands.
The present invention will further specify in conjunction with the following drawings, wherein
Fig. 1 represents aluminium-zinc binary phase diagram;
Fig. 2 represents iron-aluminum binary phasor;
Fig. 3 represents that iron-aluminium-zinc is at 450 ℃ ternary phase diagrams;
Fig. 4 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 250 hours situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests;
Fig. 5 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 500 hours situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests;
Fig. 6 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 750 hours situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests;
Fig. 7 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 1,000 hour situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests;
Fig. 8 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 1,250 hour situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests;
Fig. 9 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 1,500 hour situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests;
Figure 10 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 1,750 hour situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests;
Figure 11 represents that galvanizing and two kinds of iron and steel test pieces of the inventive method hot dip process 5%Al-Zn alloy in 2,000 hours situation of salt-fog test, wherein, (a) are traditional experiment, (b) is accelerated tests; And,
Figure 12 represents the metallographic structure of 5%Al-Zn coating.
The present invention can obtain long-lasting coating for protection against corrosion about the new technology of hot-dip 5%Al-Zn alloy on the iron and steel ground with easy step process, is applicable in fact the making of the iron and steel object product of various purposes demand. According to the present invention, a kind of method of iron and steel hot-dip 5%Al-Zn alloy may further comprise the steps:
(a) behind the cleaning treatment iron and steel material, galvanizing by dipping is processed; And
(b) thickness of coating reduce to be processed the thickness with galvanizing by dipping coating on the control steel surface, hot-dip 5%Al-Zn alloy subsequently, and obtain the 5%Al-Zn alloy layer.
According to the employed cleaning treatment of the inventive method step (a), need depending on selected iron and steel material kind, can comprise the material taxonomic revision, ungrease treatment, for the first time washing, pickling processes, for the second time washing, and in and chemicals treatment etc.; Above-mentioned various processing can be carried out according to mode known in the art technology. Moreover, after the inventive method step (b) is carried out hot-dip 5%Al-Zn alloy, can further comprise cooling processing.
The method of iron and steel hot dip process 5%Al-Zn alloy of the present invention just can not carried out in the mode of batch formula hot dipping (Bath-Type Hot Dip), also can in continous way hot dip process coil of strip, steel disc, steel plate, steel wire etc.Particularly can be readily solved for the difficulty of criticizing formula at present.In galvanizing, the aluminium that often adds trace increased mobile, brightness, and processibility is more improved in the past.But when aluminium content is above above 0.03%, the probability that steel surface does not plate heightens, itself because iron and steel plating piece surface in and medicament layer (Fluxing) closed by the calorize on zinc liquid surface easily, make plating piece in and medicament layer (Fluxing) disappear, and can't produce alloy with zinc liquid, so the steel surface casting skin can't plate zinc and present original surface.So adding the aluminium amount in zinc liquid the inside surpasses more than 0.03% and will reach 5% left and right sides time, except need improve in and medicament layer (Fluxing), when being contacted with zinc liquid, it can not be subjected to the influence of aluminium, simultaneously can be as the media of Al-Zn-Fe alloy bond, and can produce alloy for hot-dip on its surface when making iron and steel touch 5%Al-Zn liquid, just can get a desired effect.The present invention is promptly by behind galvanizing on the iron and steel, and the thickness with galvanizing coating on the thickness of coating reduction processing controls steel surface gives hot dip process 5%Al-Zn alloy treatment again, and obtains to have the iron and steel of long-lasting corrosion protection coating.
One of processing procedure of the present invention preferred embodiment, for comprising (1) material taxonomic revision, (2) skimming treatment, it is looked material require and determines to handle with sandblasting or NaOH soda, (3) washing is handled for the first time, it is just to need through soda skimming treatment person, (4) pickling operation, (5) for the second time washing is handled, and in (6) and chemicals treatment, (7) galvanizing is handled, (8) thickness of coating reduces processing, (9) hot dip process 5%Al-Zn alloy, and (10) cooling process operation are to make the 5%Al-Zn alloy layer.
By the flow process of above preferred embodiment as can be known, the method of iron and steel hot dip process 5%Al-Zn alloy of the present invention and the maximum differential of traditional galvanizing are in the method for hot dip process 5%Al-Zn alloy of the present invention, behind galvanizing, thickness of coating reduces processing in advance, and hot dip process 5%Al-Zn alloy is carried out in hot dipping in 5%Al-Zn solution again.
According to the material taxonomic revision of preferred embodiment of the present invention, it mainly is that close and materials similar is sorted out, and hot dipping is handled raising the efficiency and quality together, and the stability that can monitor quality is reached optimum efficiency.Mainly iron or iron and steel can be divided into tubing, shaped steel class, structure iron class, forged steel ironware class, screw nut class, casting ironware class, reached tower material class etc.Wherein tubing is mainly the steel pipe arrangement close according to each specification, that thickness is close together; The shaped steel class comprises angle steel, channel-section steel, i steel, H shaped steel, scale steel plate, and all kinds of light gauge steels etc.; The structure iron class is the structure of all kinds of shaped steel welding fabrications, as factory building H steel structure, be welded into large-scale structure such as bridge etc. with steel plate, even small-sized structure such as shelf bracket etc. are also classified in this, but distinguish operation according to size, thickness, shape etc., improve production capacity with controlling performance; Forged steel ironware class then comprises the iron accessory of moulding such as all kinds of shearing machines, punch press; The screw nut class comprises all kinds of screws, nut, foot screw, bolt etc.; Casting ironware class is a cast iron for example; Comprise various type copper, webs different in size with tower material class, and the minor structure thing of different shape, and bigger iron accessory is also classified in this sometimes.The main purpose of material taxonomic revision is with controlling performance and raises the efficiency is the starting point.
In the skimming treatment of the inventive method, it optionally determines to handle with sandblasting or NaOH soda.Till sandblasting is grease, paint, iron rust attached to steel surface come off fully, and can reaches specified surperficial fineness degree and be as the criterion.The soda degreasing is that the NaOH soda water solution with concentration 15% ± 5% is heated to 80 ℃ and carries out more than the temperature, checks once in about 15～30 minutes, continues about about 90 minutes, as needs can be local with hand processing clean to clean till.
Handle for washing first time of the inventive method, it is just to need through soda skimming treatment person, then needn't can directly carry out next step through this step process through the steel part of sandblasting.It is the steel part that NaOH soda water solution-treated is crossed that washing is for the first time handled, and immerses in the water of room temperature, fluctuates to make NaOH break away from steel part to carry out next step.
Pickling operation of the present invention is mainly mineral acid treatment, generally can divide into the salt acid treatment and with two kinds of vitriolization.During with the salt acid treatment, concentration of hydrochloric acid is 7～14%w/v, carries out under room temperature 15～60 minutes, and iron ion content is up to 80～100g/l in pickle solution, then need renew hydrochloric acid lotion and proceed.During with vitriolization, sulfuric acid concentration is 6～14%w/v, carries out 5～30 minutes under 60～65 ℃ of temperature, generally interchangeable eo-acid when iron ion content reaches 50g/l in the pickle solution, iron ion content reaches as high as 80～120g/l and renews sulfuric acid lotion again, but follow-up washing is comparatively difficult.Can optionally add inhibitor in the pickling operation, prevent that iron or iron and steel are subjected to hydrochloric acid or sulfuric acid corrosion again, known inhibitor kind all can be used in the inventive method, and its usage quantity is 2 weight %.
The more occupied ground of treatment trough is bigger during the salt acid treatment, and speed is slower, and gas disperses easily, influences air quality, but iron and steel more can not produce hydrogen embrittlement; Otherwise during with vitriolization, treatment trough is less, and institute takes up space lessly, and processing speed is also very fast, and gas is difficult for dispersing, but hydrogen can be attached on the steel part, produces the situation of hydrogen embrittlement, so can be according to the pattern of decision pickling operations such as actual space and equipment.
Steel part after the cleanup acid treatment is immersed in the water, fluctuate, vibrate to remove the acid solution of its remained on surface, this i.e. washing is for the second time handled.
In carrying out subsequently and chemicals treatment, its effect mainly is to make the iron and steel surface adhere to one deck to help the plating medicament, and the performance expected effect impels Fe-Zn-Al to produce alloy rapidly when hot dip process, produces the coating of one deck Jie Fe-Zn-Al metal in steel surface.Be applicable to of the present invention in and medicament kind be sodium-chlor, phosphoric acid salt, zinc ammonium chloride etc., with zinc chloride by being example, its concentration is 30～35w/v%, be preferably the pH potential of hydrogen and be controlled in 3.0～4.5 and under 65～80 ℃ of temperature, carry out, as needs also can add 2% tensio-active agent in and in the chemicals treatment.On the other hand, in and can iron ion content in the medicament treating processes as index, when promptly iron ion content surpasses 7w/v% and the medicament aqueous solution and is brown, must cleaning and filtering equipment, and the capacity of filter plant can filter full groove once in about 2～4 hours.
The method of iron and steel hot dip process 5%Al-Zn alloy according to the present invention, wherein galvanizing is handled identical with the processing mode of general galvanizing, temperature is controlled in 445 ℃ ± 5 ℃ usually, and the operating time must be grasped proper, and is as shown in table 1 for steel configuration steel and piped operating time.
Table 1
| Pattern | Thickness m/m | Time (second) |
| | 3～4.5 | 30～75 |
| 5～6 | 75～150 | |
| 9～12 | 150～180 | |
| Surpass 15 | More than 180 | |
| Tubing | Below 3 | 45～120 |
| 3～6 | 120～150 | |
| Surpass 6 | 150～180 |
Generally, when previous operations, must know planning with material immersion plating in batches, as the utilization of smelting tool, the operation together that material is similar etc., the material arrangement before pickling all must be carried out.When immersion plating temperature maintenance one regularly, the operating time then can be according to steel part size, thickness classification and different, does not wait by 15 seconds to 600 seconds, is preferably 30 seconds to 300 seconds; The thick more person of general thickness, the time that galvanizing is handled is of a specified duration more.
After the invention is characterized in that galvanizing is handled, thickness of coating need be reduced processing, with the thickness of controlling galvanizing coating on the steel surface and carry out hot dip process 5%Al-Zn alloy subsequently.In other words, after galvanizing finishes, before the immersion plating 5%Al-Zn alloy, thickness of coating reduce to handle can be when keeping galvanizing to handle in the zinc liquid aluminium content near 0.03%, liquid level is flowed fast, and when taking out iron and steel, spray, make zinc-plated thickness reduction on the steel surface so that air or ammonium chloride etc. are powerful.
After treating that in the present invention thickness of coating reduces processing, get final product hot dipping 5%Al-Zn alloy, and on steel surface, obtain long-lasting 5%Al-Zn alloy layer.The steel part that surface treatment is finished directly places hot dip process 5%Al-Zn alloy liquation, its temperature is controlled in 440 ℃ ± 20 ℃, preferable in 440 ℃ ± 10 ℃, operating time is as shown in table 2, and it is respectively by 15 seconds to 600 seconds, to be preferably 30 seconds to 300 seconds according to size, thickness.When hot dip process 5%Al-Zn alloy carry out preceding and finish to propose by liquid level before, alloy liquation liquid level must keep totally avoiding oxide compound or impurity to be attached on the steel part.
Table 2
| Pattern | Thickness m/m | Time (second) |
| | 3～4.5 | 30～75 |
| 5～6 | 75～120 | |
| 9～12 | 120～150 | |
| Surpass 15 | More than 150 | |
| Tubing | Below 3 | 45～120 |
| 3～6 | 120～150 | |
| Surpass 6 | 150～180 |
After the inventive method step (b) is carried out hot dip process 5%Al-Zn alloy, optionally can further give cooling process.When the steel part of finishing hot dip process 5%Al-Zn alloy, be immersed in 40 ℃～70 ℃ the flowing water about about 30～90 seconds and cooled off.Various iron and steel required time in cooling process is as shown in table 3.
Table 3
| Pattern | Thickness m/m | Time (second) |
| | 3～4.5 | 30～45 |
| 5～6 | 30～60 | |
| 9～12 | 45～60 | |
| Surpass 15 | More than 60 | |
| Tubing | Below 3 | 30～60 |
| 3～6 | More than 30～60 | |
| Surpass 6 | More than 60 |
After hot dip process 5%Al-Zn alloy and cooling are finished, must carry out the visual QC inspection arrangement on surface, even with the instrument test thickness of coating with controlling performance, reach due regulation.
Behind above-mentioned steps of the present invention, particularly step (a) clean iron and steel material, galvanizing is handled; Reach step (b) thickness of coating and reduce the thickness of handling with galvanizing coating on the control steel surface, hot dip process 5%Al-Zn alloy can obtain long-lasting corrosion protection 5%Al-Zn alloy layer on steel surface subsequently.With regard to the steel material of the prepared hot dip process 5%Al-Zn of the present invention alloy, find that by analysis in the 5%Al-Zn system, the distribution of Al is much more complicated.According to the phasor of Al-Zn shown in Figure 1,5%Al-Zn forms the structure of eutectic (eutectic) under suitable temperature control, so overwhelming majority structure for this reason in the 5%Al-Zn coating.But because the affinity degree (affinity) of Al and Fe is good than Al and Zn, at Jie's metal compound layer of the Al-Fe that can form one deck such as Fig. 2 at the interface.If further act on Jie's metal level that promptly forms as the Fe-Zn-Al ternary structural of Fig. 3 with Fe, Zn again.The growth of this Jie's metal level has decisive influence to the thickness and the corrosion stability of coating.
On the other hand, be the resistance to corrosion of understanding coating and the mechanical properties of every ferrous materials, the steel material of the prepared hot dip process 5%Al-Zn of the present invention alloy, through every experimental study such as salt-fog test, exposure test, electrochemical test, microscopic test, hardness test, draw bit test etc., except confirming that coating red rust in salt mist environment is just sent out the time is more than 2～3 times the time of general galvanizing, and other are every more to meet the industry demand.Therefore, can confirm that more the method for using iron and steel hot dip process 5%Al-Zn alloy of the present invention promotes corrosion protection result greatly and has excellent mechanical properties, effectively solve previous difficulty really.
Now described in detail the present invention with the following example, but do not meaned the content that the present invention only is confined to these examples and is disclosed.
Embodiment:
It is base material that the SS41 tool steel is adopted in test piece, and coating has two kinds: 5%Al-Zn and Zn; Wherein coating is that 5%Al-Zn person promptly makes according to the method for iron and steel hot dip process 5%Al-Zn alloy of the present invention, and coating makes according to traditional conventional approaches for Zn person.
According to the inventive method, the SS41 tool steel was handled about 90 minutes more than the temperature so that the iron and steel degreasing is then washed for the first time and handled in 80 ℃ through 15% ± 5% NaOH soda water solution earlier.Hydrochloric acid soln with 10%w/v concentration carried out the pickling operation about 45 minutes afterwards, and iron ion content is up to 80～100g/l in pickle solution, then need renew hydrochloric acid lotion and proceed, and washing is handled for the second time.And with zinc ammonium chloride as in and chemicals treatment, wherein zinc ammonium chloride concentration is 35w/v%, and the pH potential of hydrogen is controlled in 4.0 and carry out under 70 ℃ of temperature.Galvanizing is handled under 445 ℃ of temperature subsequently, when taking out iron and steel, removes when keeping galvanizing to handle in the zinc liquid aluminium content near 0.03%, makes outside liquid level flows fast, and sprays with air strong, makes that zinc-plated thickness reduces on the steel surface.Directly hot dip process in the 5%Al-Zn of 440 ℃ of temperature alloy liquation last was cooled off in 70 ℃ flowing water in about about 60 seconds, to make the 5%Al-Zn alloy layer in steel surface.
The finished product experiment of processing procedure of the present invention:
The finished product of processing procedure of the present invention is via every experiment, comprise 1, salt-fog test, 2, exposure test, 3, electrochemical test, 4, tension test, 5, microhardness test, 6, microscopic test etc., all show the product of processing procedure of the present invention, corrosion protection result and mechanical property that tool is quite excellent.
1, salt-fog test: as can be known behind the iron and steel hot dip process 5%Al-Zn alloy, confirm that red rust just goes out the time more than 2～3 times that the time is general galvanizing in salt mist environment by Fig. 4～Figure 11 and table 4.
Table 4, salt-fog test time and test piece surface generate the red rust area ratio
| Test period (hour) | 250 | 500 | 750 | 1000 | 1250 | 1500 | 1750 | 2000 | ||
| The red rust area | Traditional experiment | 5％Al-Zn | - | - | - | - | - | 2.6％ | 6.3％ | 10.3％ |
| Galvanizing | - | - | 5.2％ | 8.3％ | 18.7％ | 25.5％ | 31.4％ | 33.1％ | ||
| Accelerated tests | 5％Al-Zn | - | - | - | - | 1.4％ | 3.7％ | 4.2％ | 8.5％ | |
| Galvanizing | - | - | 8.6％ | 9.1％ | 21.4％ | 26.8％ | 31.9％ | 42.6％ | ||
2, the steel part of galvanizing and hot dip process 5%Al-Zn alloy carries out Jia Fanni and soaks and put experiment in 3%NaCl saturated air solution, Coupling Potential and Jia Fanni electric current through the time variation.By the Jia Fanni size of current, detect and learn that hot dip process 5%Al-Zn alloy is better than galvanizing.Learn in the Coupling Potential that galvanizing is better at the beginning, but medium-term and long-term, more superior with 5%Al-Zn coating.In villaumite on, table 5 is the corrosion potential of three kinds of test pieces, in the test of three different concns, corrosion potential is 5%Al-Zn coating＞pure zinc coating＞5%Al-Zn mother metal, 5%Al-Zn coating is the most valuable as can be known, in sulfide on, in shown in the table 5, contain in the low sulfur amount environment comparatively valuable with 5%Al-Zn coating.But in the high environment of sulphur content, then galvanizing is comparatively valuable.
Table 5, three kinds of test piece corrosion potential Ecorr (V) under different etchant solutions
| Etchant solution test piece kind | NaCl | Na 2S 2O 3 | |||||
| 0.5M | 2M | Saturated | 0.5M | 2M | Saturated | ||
| Not deoxygenation | Deoxygenation | ||||||
| Immersion plating 5% Al-Zn | -1.316 | -1.340 | -1.312 | -1.285 | -1.014 | -1.021 | -1.020 |
| Galvanizing | -1.340 | -1.348 | -1.358 | -1.341 | -1.068 | -0.811 | -1.012 |
| The 5%Al-Zn mother metal | -1.460 | -1.446 | -1.433 | -1.427 | -1.380 | -1.305 | -1.444 |
Unit: volt (V)
3, tension test
Stretch test result sees Table 6.Test piece after hot dip process, the required minimum stress of its distortion has significant increase, i.e. the ability of resistance to deformation significantly increases, but disrumpent feelings stress then variable quantity is big not as the STRESS VARIATION amount of distortion, promptly tension strength at break there is no significantly and to promote.The variable quantity of immersion plating 5%Al-Zn all comes highly than galvanizing.
Zinc itself is low intensive metal, and in the system of galvanizing, zinc is plating that the increase of intensity is not the contribution of pure zinc layer on steel, and mainly is the increase from Fe-Zn alloy layer intensity.In the system of 5%Al-Zn, by the Al-Zn phasor as can be known, do not produce Jie's metallic compound between Al-Zn, only produce the difference in rich zinc district and rich aluminium district, in addition, Al in the coating and Fe can form Jie's metallic compound, believe it is the major cause that intensity increases.
Table 6, stretch test result
| Yield strength | Tensile strength | Unit elongation | ||||
| kg/mm 2 | Variable quantity | kg/mm 2 | Variable quantity | ％ | Variable quantity | |
| SS41 | 26.53 | - | 35.04 | - | 146.8 | - |
| Galvanizing | 29.87 | 12.6％ | 36.46 | 4.1％ | 140.2 | -4.6％ |
| Immersion plating 5%Al-Zn | 31.23 | 17.7％ | 37.18 | 6.1％ | 136.1 | -7.3％ |
*Variable quantity refers to the variation of coated coupon and SS41 ground.
Variable quantity=(P
Coating-P
SS41)/p
SS41* 100%; P refers to respectively measure character
4, microhardness test
Table 7 is each positive microhardness test-results in test piece surface.Because thickness of coating is less than microhardness test impression length, so can't obtain the hardness and the distribution thereof of coating cross section.In the galvanizing, the hardness of pure zinc layer (η) is 70Hv according to document, and to test resulting hardness value be the most surperficial contribution of coating to microhardness as can be known.5%Al-Zn is because Al is dissolved in the effect that solution strengthening is arranged in the base of Zn, so the purer zinc of hardness comes highly.
Table 7, microhardness test-results
| SS41 | Galvanizing | Immersion plating 5%Al- | |
| 1 | 145.1 | 66.4 | 83.9 |
| 2 | 146.0 | 67.4 | 90.1 |
| 3 | 154.0 | 67.6 | 91.9 |
| 4 | 157.4 | 70.0 | 106.4 |
| 5 | 159.4 | 71.0 | 107.5 |
| Mean value *(Hv) | 152.5 | 68.3 | 96.1 |
*Mean value is after removing maximum and minimum value, three intermediate values average.
According to Figure 12, the subregion of metallograph, Chemical Composition is as shown in table 8 below:
The chemical constitution of table 8,5%Al-Zn coating (wt%)
| Al | Zn | Fe | O | The Al/Fe atomic ratio | |
| The surface | 6.2 | 70.2 | 1.8 | 21.8 | - |
| 1 | 5.3 | 83.1 | - | 11.6 | - |
| 2 | 2.6 | 85.9 | - | 11.5 | - |
| 3 | 30.4 | 53.8 | 8.3 | 7.5 | 7.6 |
| 4 | 42.4 | 36.0 | 10.0 | 11.6 | 8.8 |
| 5 | 13.5 | 71.7 | 3.3 | 11.5 | 8.5 |
| 6 | 36.6 | 39.1 | 11.8 | 12.5 | 6.4 |
So far, hot dip process 5%Al-Zn alloy only rests on the steel plate, coil of strip, steel disc etc. of plating continous way, and can't mass production, more can't break through this superior product application on the plating method of batch formula hot dip process 5%Al-Zn alloy.So a lot of ferrous materials is arranged at present, steel structure material as the electric line high voltage iron tower electric substation of Taiwan Power Company, harbour, bay equipment, every iron and steel facility of motorway, railway electrification, the steel equipment of following high-speed railway, the bridge construction of Highway Administration Bureau, even six present light construction or the like, all can utilize the present invention to be applicable to the processing procedure of the hot dip process 5%Al-Zn alloy of any steel product, with mass production method, make the anticorrosion material more more superior than existing market product.
Claims (15)
1, the method for a kind of batch of formula iron and steel hot dip process 5%Al-Zn alloy is may further comprise the steps:
(a) behind the clean iron and steel material, galvanizing is handled; And
(b) when taking out iron and steel, spray so that gas is powerful, zinc-plated thickness is reduced and carry out thickness of coating and reduce and handle, hot dip process 5%Al-Zn alloy subsequently, and obtain the 5%Al-Zn alloy layer.
2, the method for claim 1, wherein the time of iron and steel galvanizing is 15 seconds to 600 seconds in the step (a).
3, method as claimed in claim 2, wherein the time of iron and steel galvanizing is 30 seconds to 300 seconds in the step (a).
4, the method for claim 1, wherein being used for the powerful gas that sprays of gas is air or ammonium chloride.
5, the method for claim 1, wherein the temperature of hot dip process 5%Al-Zn alloy is controlled in 440 ℃ ± 20 ℃, and the operating time is between 15 seconds to 600 seconds.
6, method as claimed in claim 5, wherein the temperature of hot dip process 5%Al-Zn alloy is controlled in 440 ℃ ± 10 ℃, and the operating time is between 30 seconds to 300 seconds.
7, the method for claim 1, wherein clean is looked selected iron and steel material kind needs, comprise material taxonomic revision, skimming treatment, washing for the first time, cleanup acid treatment, washing for the second time, and in and chemicals treatment.
8, the method for claim 1, wherein step (b) carries out further comprising cooling process after the hot dip process 5%Al-Zn alloy.
9, method as claimed in claim 7, wherein skimming treatment is sandblasting.
10, method as claimed in claim 7, wherein skimming treatment is to handle with NaOH soda.
11, method as claimed in claim 10 wherein after NaOH soda is handled, is handled with washing.
12, method as claimed in claim 7, wherein cleanup acid treatment is a mineral acid treatment.
13, method as claimed in claim 12, wherein cleanup acid treatment is with the salt acid treatment.
14, method as claimed in claim 12, wherein cleanup acid treatment is with vitriolization.
15, the method for a kind of batch of formula iron and steel hot dip process 5%Al-Zn alloy comprises (1) material taxonomic revision; (2) skimming treatment, it is looked steel and need and determine to handle with sandblasting or NaOH soda; (3) washing is handled for the first time, and it is just to need through soda skimming treatment person; (4) pickling operation; (5) washing is handled for the second time; (6) in and chemicals treatment; (7) galvanizing is handled; (8) when taking out iron and steel, spray so that gas is powerful, zinc-plated thickness is reduced and carry out thickness of coating and reduce and handle; (9) hot dip process 5%Al-Zn alloy; And (10) cooling process operation, to make the 5%Al-Zn alloy layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB991008871A CN1192120C (en) | 1999-02-24 | 1999-02-24 | Technology for hot-dipping 5% Al-Zn alloy on iron or steel |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB991008871A CN1192120C (en) | 1999-02-24 | 1999-02-24 | Technology for hot-dipping 5% Al-Zn alloy on iron or steel |
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| CN1264750A CN1264750A (en) | 2000-08-30 |
| CN1192120C true CN1192120C (en) | 2005-03-09 |
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| CNB991008871A Expired - Fee Related CN1192120C (en) | 1999-02-24 | 1999-02-24 | Technology for hot-dipping 5% Al-Zn alloy on iron or steel |
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| JP2013227594A (en) * | 2012-04-24 | 2013-11-07 | Nippon Steel & Sumitomo Metal Corp | Hot dip galvanized steel tube and method for manufacturing the hot dip galvanized steel tube |
| DE102020200326A1 (en) * | 2020-01-13 | 2021-07-15 | Thyssenkrupp Steel Europe Ag | Process for the production of a surface-refined and surface-conditioned steel sheet |
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