CN1303236C - Zinc bismuth multicomponent alloy used for hot dip galvanizing of steel and iron members and hot dip galvanizing method therefor - Google Patents

Abstract

The present invention relates to a zinc alloy and a hot dipping galvanizing method. The present invention has the technical scheme that a zinc bismuth multi-component alloy A containing bismuth and used for galvanizing a hot dipping steel component is composed of 0.05 to 0.1 wt% of Bi, 0.05 to 0.09 wt% of Al, 0.01 to 0.05 wt% of rare earth metal RE, 0 to 0.05 wt% of Ni and zinc and unavoidable impurities as the rest, wherein the rare earth metal RE is a mixture of at least two of lanthanum (La), cerium (Ce) and praseodymium (Pr). A hot dipping galvanizing method for a steel product containing Si and/or P adopts the zinc and bismuth multi-component alloy of the components as a zinc bath. The present invention reasonably controls the content of the aluminum, the nickel and the rare earth (the rare earth metal RE), and simultaneously adds a bismuth element to the alloy so that the flowing property of the zinc bath is obviously improved. The thickness of a plating layer is properly reduced when the anticorrosive performance and the mechanical performance of the plating layer are ensured.

Description

Zinc-bismuth multi-element alloy for hot-dip galvanizing of iron and steel components and method thereof

technical field

The invention relates to a zinc alloy for galvanizing steel components under heated conditions.

Background technique

At present, the zinc bath used in the hot-dip galvanizing industry at home and abroad has basically been improved from a pure zinc bath to a zinc alloy bath. The corrosion resistance, surface quality, and bonding force of the coating obtained by the latter have made great progress. Various zinc alloy baths have the problems of poor melt fluidity, zinc flow, zinc nodules, many burrs, and poor surface finish of the coating. Although various improved alloys have solved some of these problems to a certain extent, there are still defects, such as Zn-Al alloys are very effective in improving the brightness of the coating, but the melt segregation is large and the zinc bath is sticky; Zn-Al- Rare earth metal RE alloys can improve the wettability of steel and zinc very well, but the composition fluctuates greatly and the element burns seriously; The Sandelin effect has a narrower scope. In summary, the present various zinc alloy baths need to be further improved.

Contents of the invention

The purpose of the present invention is to provide a zinc-bismuth multi-element alloy and its method for hot-dip galvanizing of iron and steel components, which can significantly improve the fluidity of the zinc bath, and properly reduce the corrosion resistance and mechanical properties of the coating while ensuring the corrosion resistance and mechanical properties of the coating. Coating thickness.

Another object of the present invention is to provide a new hot-dip galvanizing method, which uses a zinc-bismuth multi-element alloy as a zinc bath to solve the problems of poor melt fluidity, zinc flow, zinc nodules, and many burrs in hot-dip galvanizing. , Poor surface finish of the coating, etc.

The technical scheme of the present invention is: a kind of bismuth-containing zinc-bismuth multi-element alloy used for galvanizing hot-dip iron and steel components, which consists of 0.05-0.1% (wt) Bi; 0.05-0.09% (wt) Al; 0.01 ~0.05% (wt) rare earth metal RE; 0 ~ 0.05% (wt) Ni; the rest is zinc and unavoidable impurities, and the rare earth metal RE is lanthanum (La), cerium (Ce), praseodymium (Pr ) is a mixture of at least two of them.

As a further improvement to the present invention, the rare earth metal RE is an equal amount mixture of any two of lanthanum (La), cerium (Ce) and praseodymium (Pr).

As a further improvement to the present invention, the rare earth metal RE is a mixture of lanthanum (La), cerium (Ce), and praseodymium (Pr), and the mixing weight ratio is: lanthanum (La): cerium (Ce): praseodymium (Pr) =2:2:1.

A hot-dip galvanizing method for steel products that may contain Si and/or P, using the above-mentioned zinc-bismuth multi-element alloy as a zinc bath.

Beneficial effect

The invention reasonably controls the content of aluminum, nickel and rare earth metal RE in the alloy, and at the same time adds bismuth element to the alloy, so that the flow performance of the zinc bath is obviously improved, and the thickness of the coating is appropriately reduced while ensuring the corrosion resistance and mechanical properties of the coating. The fluidity of the product obtained in the present invention can be detected by the disclosed mold of Chinese patent ZL03248893.9, and the detection method and results are as follows:

1. Fluidity comparative test between the present invention and other zinc alloys

(1) Scoop casting fluidity test

Test method: use the snake-shaped mold disclosed in Chinese patent ZL03248893.9, melt the zinc-bismuth alloy, heat up to 500°C, take a certain amount of liquid metal with an iron spoon and pour it into the snake-shaped mold in the same way, let the liquid metal When the liquid metal in the mold no longer flows, stop pouring the molten metal into the serpentine mold. After the metal in the serpentine mold has cooled and solidified, measure the length of the metal flow. The test is repeated and the test results are averaged. Zinc-bismuth alloys with pure zinc and bismuth contents of 0.01%, 0.06%, 0.1%, 0.16% and 0.2% were selected for testing.

(2) Maofu constant temperature resistance furnace test

Test method: The serpentine mold disclosed in Chinese patent ZL03248893.9 is used, the holding time is 3 hours, and the test is done by utilizing the nature of the natural flow of liquid metal after the alloy is melted. When the liquid alloy no longer flows, stop the constant temperature, and cool and solidify the alloy with the furnace. After coming out of the furnace, measure the length of the alloy flowing naturally in the liquid state in the serpentine mold, repeat the test, and take the average value of the results.

Weigh the same weight, bismuth content of 0.02%, 0.04%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% , 0.7%, 0.8%, 0.9% and 1% zinc-bismuth alloys were tested in a Maofu constant temperature resistance furnace with a constant temperature of 460 °C.

According to the results obtained from the above tests, the relationship diagram between the content of bismuth and the fluidity of the alloy shown in Fig. 1 was drawn.

It can be seen from Figure 1 that when the Bi content in the multi-component alloy is below 0.1%, the fluidity of the alloy shows a parabolic increase with the increase of the Bi content, and a peak appears when the Bi content reaches 0.1%. When the content of Bi is 0.15%, it shows a parabolic decrease with the increase of Bi content. After the content of Bi is greater than 0.2%, the fluidity of the alloy shows an increasing trend with the increase of Bi content, but the cost increases; therefore, the zinc-bismuth alloy obtained in the present invention has good fluidity and is cost-effective. best.

2, coating thickness inspection of the present invention:

Inventor simulates the process condition of hot-dip factory in the laboratory, uses Zn-Ni alloy bath, Zn-Al-rare earth metal RE alloy bath, alloy bath of the present invention to carry out hot-dip plating test, and hot-dip plating test process and condition are as follows:

Process flow: hydrochloric acid pickling→water washing→helping plating→drying→hot-dip plating→cooling→subsequent processing→finished product

Hydrochloric acid pickling: use 8% to 20% hydrochloric acid concentration, pickle at room temperature for 5 to 10 minutes;

Water washing: a large amount of tap water washes away the residual acid and iron salts on the plated parts;

Flux: Use conventional flux, that is, 100g/l NH ₄ Cl + 480g/l ZnCl ₂ , the concentration of NH ₄ Cl and ZnCl ₂ can be appropriately changed according to the dryness and humidity of different regions, and the temperature of flux is 80 Above ℃, the fluxing time is 0.5 to 1 minute.

Drying: Use a drying temperature of 100°C to 200°C until there is no free water

Hot-dip galvanizing: galvanized at 450°C to 490°C, dipping time is 30 seconds to 5 minutes

Cooling: divided into air cooling, water cooling and first air cooling and then water cooling

The test data of the obtained product are shown in Fig. 2 . The coating thicknesses of the three alloys obtained are as shown in Figure 2. Among Figure 2, a represents the Zn-Ni alloy bath, b represents the Zn-Al-rare earth metal RE alloy bath, and c represents the Zn-Bi-Al-rare earth metal RE alloy bath . As can be seen from Fig. 2, the coating thickness of the present invention represented by c is the smallest.

Corrosion resistance:

Select pure zinc and bismuth content to be 0.01%, 0.06%, 0.1%, 0.16%, Al content is about 0.05%, rare earth metal RE content is about 0.05%, and the hot-dip plating time is 30 seconds and 3 minutes respectively. Corrosion tests were carried out using galvanized steel strips of the present invention. Test method: GB6458-86NSS neutral hydrochloric acid corrosion test chamber, test equipment: HK-1 hydrochloric acid corrosion test chamber.

Test conditions: salt spray deposition rate (80cm ² ) 1~2ml, corrosion system is 50±g/ml NaCl solution, pH value is 6.5~7.2, test temperature: 35℃±2℃, test cycle: intermittent spray 8 The hour stops for 16 hours, and the total time is 96 hours. The test results are shown in Table 1.

The number 1# in the table is pure zinc, 2# is Zn-0.01%Bi alloy, 3# is Zn-0.1%Bi alloy, 4# is Zn-0.1%Al-0.03% rare earth metal RE alloy, 5# is Zn- 0.1% Bi-0.05% Al-0.05% rare earth metal RE alloy is the product of the present invention, 6 # is Zn-0.1% Bi-0.1% rare earth metal RE-0.1% Ni alloy, 7 # is Zn-0.1% Ni alloy.

The obtained results show that with the increase of bismuth content, the corrosion rate value decreases and the corrosion resistance of the alloy increases.

Mechanical behavior:

1. Testing test of flexibility of hot-dip galvanized alloy coating

Detection method: bending method

Testing equipment: flexible multi-axis rod tester

Detection object: A3 steel zinc alloy coating

Statutory standard: if the coating has texture, cracks and peeling off, it is unqualified

In the range of 430-470°C, hot-dip _A3 steel thin slices in Zn-Ni, Zn-Al rare earth metal RE, Zn-Bi multiple alloy baths, and randomly select 3 slices from each alloy coating thin slices at different temperatures to make The flexibility was tested by the multi-axis rod test, and the test results showed that the coating integrity of each sample was good, and there were no damage phenomena such as reticulation, cracks and peeling, and the quality was qualified. The present invention outperforms other results.

2. Hot-dip galvanized coating adhesion testing test

Detection method: circle method

Testing equipment: adhesion tester

Detection object: A ₃ steel zinc alloy coating

Evaluation standard: Evaluate the completeness of the scratch coating according to the seven-level standard sample

Select the temperature range of 430 ℃ ~ 470 ℃, hot-dip plate A ₃ steel sheet in Zn-Ni, Zn-Al-rare earth metal RE, Zn-Bi multi-alloy bath, and randomly select three pieces of alloy coating sheets at different temperatures as attachments. Focus on the detection test and get the average value. The results show that the coating integrity of each sample is good, and the reference standard samples all reach grade seven.

The present invention outperforms other results

3. Impact detection test of hot-dip zinc alloy coating

Detection method: impact method

Testing equipment: impact testing machine

Detection object: A ₃ steel zinc alloy coating

Evaluation standard: cracks, wrinkles and peeling of the coating are unqualified

In the range of 430°C to 470°C, 3 pieces of A ₃ steel sheets with Zn-Ni, Zn-Al rare earth metal RE, and Zn-Bi multivariate were randomly selected, and impact tests were carried out. The test results showed that: the alloy coating on the A ₃ steel sheets good quality. The present invention outperforms other results.

Description of drawings

Below in conjunction with accompanying drawing, invention is further described:

Figure 1 The relationship between bismuth content and its alloy fluidity

Fig. 2 the relation figure of the present invention and other two kinds of alloy hot-dip time and thickness

Detailed ways

Example 1

A bismuth-containing zinc-bismuth multi-element alloy A for galvanizing hot-dip iron and steel components, the composition of which is 0.05% (wt) Bi; 0.09% (wt) Al; 0.01% (wt) rare earth metal RE; 0.05 % (wt) of Ni; the rest is zinc and unavoidable impurities, and the rare earth metal RE is a mixture of lanthanum (La): cerium (Ce) = 1:1.

Example 2

A bismuth-containing zinc-bismuth multi-element alloy A for galvanizing hot-dip iron and steel components, the composition of which is 0.1% (wt) Bi; 0.09% (wt) Al; 0.01% (wt) rare earth metal RE; 0.05 % (wt) Ni; the rest is zinc and unavoidable impurities, and the rare earth metal RE is a mixture of lanthanum (La): cerium (Ce): praseodymium (Pr)=2:2:1.

Example 3

A bismuth-containing zinc-bismuth multi-element alloy A for galvanizing hot-dip iron and steel components, the composition of which is 0.05% (wt) Bi; 0.05% (wt) Al; 0.05% (wt) rare earth metal RE; 0.05 % (wt) Ni; the rest is zinc and unavoidable impurities, and the rare earth metal RE is a mixture of lanthanum (La): cerium (Ce)=1:1.

Example 4

A bismuth-containing zinc-bismuth multi-element alloy A for galvanizing hot-dip iron and steel components, the composition of which is 0.1% (wt) Bi; 0.09% (wt) Al; 0.05% (wt) rare earth metal RE; 0 % (wt) Ni; the rest is zinc and unavoidable impurities, and the rare earth metal RE is a mixture of cerium (Ce): praseodymium (Pr)=1:1.

Table 1 Salt spray corrosion test results serial number Sample size/mm W front/g After W/g Corrosion rate/g/m ² h Dipping time/S 1-1 4.5×3.1×1.58 14.973 14.928 10.03 300 1-2 2×3.1×1.58 21.769 21.692 11.06 180 2-1 5×3.1×1.58 17.958 17.915 9.20 30 2-2 5×3.1×1.58 20.466 20.420 8.47 180 3-1 5×3.1×1.58 16.222 16.199 5.52 30 3-2 6×3.1×1.58 17.785 17.759 4.74 180 4-1 5×3.1×1.58 13.153 13.126 5.84 30 4-2 4×3.1×1.58 14.027 14.002 5.51 180 5-1 5×3.1×1.58 16.450 16.390 1.00 30 5-2 5×3.1×1.58 19.605 19.550-650 0.849 60 5-3 8×3.1×1.58 27.575 27.570 1.23 120 5-4 8×3.1×1.58 32.695 32.689 1.23 180 6-1 8×3.1×1.58 24.806 24.788 2.46 30 6-2 8×3.1×1.58 26.706 26.692 2.46 60 6-3 5×3.1×1.58 23.320 23.304 2.944 120 6-4 5×3.1×1.58 22.393 22.380 2.87 180 7-1 8×3.1×1.58 37.744 34.723 3.69 30 7-2 8×3.1×1.58 26.809 26.782 3.61 60 7-3 8×3.1×1.58 23.989 23.969 3.42 120 7-4 6×3.1×1.58 20.363 20.337 4.106 180

Claims (4)

1, a kind of galvanized, bismuthiferous zinc bismuth multicomponent alloy of hot dipping steel and iron member that is used for, it is characterized in that: it consists of 0.05～0.1% (wt) Bi; The Al of～0.09% 0.05 (wt); 0.01 the rare earth metal RE of～0.05% (wt); The Ni of 0～0.05% (wt); All the other are zinc and unavoidable impurities, and described rare earth metal RE is at least two kinds a mixture among lanthanum (La), cerium (Ce), the praseodymium (Pr).

2, galvanized, the bismuthiferous zinc bismuth multicomponent alloy of hot dipping steel and iron member that is used for according to claim 1, it is characterized in that: described rare earth metal RE is the wantonly two kinds equal amount of mixture of lanthanum (La), cerium (Ce), praseodymium (Pr).

3, galvanized, the bismuthiferous zinc bismuth multicomponent alloy of hot dipping steel and iron member that is used for according to claim 1, it is characterized in that: described rare earth metal RE is the mixture of lanthanum (La), cerium (Ce), praseodymium (Pr), and the mixed weight ratio is: lanthanum (La): cerium (Ce): praseodymium (Pr)=2: 2: 1.

4, a kind of hot dip galvanizing method that optionally contains the steel work of Si and/or P is characterized in that: adopt the zinc bismuth multicomponent alloy of claim 1-3 component described in each to bathe as zinc.

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