KR940008940B1 - Ni-cr-fe alloy and producing method thereof - Google Patents

Abstract

The method is for manufacturing alloy having Fe and Ni, Cr for a main component, and alloy that can melt metals in the air. The main component of alloy has 60.01-74.48 wt.% of Ni, 15.0-28.0 wt.% of Cr, 1.20-16.0 wt.% of Fe and added other components are as follows; Cu: 0.05-2.5, Ti: 0.10-1.80, Zr: 0.10-0.50, Al: 0.30-0.50, C: 0.01-0.05, V: 0.01-0.50, Ca: 0.01-0.05, Nb: 0.10-0.90, Mo: 1.00-9.00. The process comprises: A) melting composites with a high-frequency induction furnace; B) soaking for 1 hr at 1150 deg.C; C) homogenizing treatments; D) cold rolling to 90 % pressure ratio.

Description

High corrosion resistance Ni-Cr-Fe alloy and its manufacturing method

1 is an optical micrograph of a microstructure of a conventional Hestelloy alloy.

2 is an optical micrograph showing the formation of precipitates showing precipitation strengthening of the Ni-Cr-Fe alloy prepared in Example 6 of the present invention.

Figure 3 is an optical micrograph showing the formation of precipitates showing precipitation strengthening of the Ni-Cr-Fe-based alloy prepared in Example 7 of the present invention.

The present invention exhibits high corrosion resistance against various corrosion atmospheres such as hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, etc., and has a new high corrosion resistance Ni-Cr-Fe alloy having excellent mechanical properties due to precipitation strengthening by addition of trace alloy elements. And a manufacturing method thereof, in particular an economical and highly corrosion-resistant alloy mainly composed of iron, nickel and chromium without using expensive W at all, and a simple and economical alloy capable of dissolving various metals in the atmosphere It relates to a manufacturing method of.

Commercially available corrosion-resistant alloys are nickel-based alloys that can withstand even the most corrosion-resistant atmospheres.These alloys make use of the characteristics of reformer tubes, cracking tubes and nuclear power plant structural materials, and pipe materials for heat exchangers. It is used in many industries including

Typical examples of such corrosion resistant alloys include Hestelloy and Monel alloys. Although these alloys are easy to manufacture and have suitable mechanical properties, Hestelloy is weak in hydrofluoric acid and Monel alloy is nitric acid. Because of its weakness, it was impossible to use simultaneously under various corrosion conditions such as hydrochloric acid, hydrofluoric acid, nitric acid and sulfuric acid.

Accordingly, nickel-based corrosion resistant alloys having low cost and easy manufacturing have been developed as substitutes for the corrosion resistant alloys, but the manufacturing process and workability are inferior to those of the conventional Hastelloy. Inconel 601,604,751 (INCONEL 601,604,751), a nickel-based super heat-resistant alloy that has been developed, is a structural material developed by focusing on alloy design for use in special purposes such as oxidation resistance and creep properties at high temperature. Special-purpose alloys must be melted in a vacuum and require special processes such as mechanical alloying. Therefore, the manufacturing process is complicated, and their application to popular corrosion-resistant alloys other than special-purposes is restricted. It was difficult to commercialize with a corrosion resistant alloy. Inconel alloys also exhibit excellent corrosion resistance to nitric acid, hydrofluoric acid, sulfuric acid, etc., but have weak drawbacks with hydrochloric acid.

On the other hand, Japanese Patent Laid-Open Nos. 62-158844 and 62-158847 disclose high-strength nickel alloys exhibiting excellent corrosion resistance in a sour gas environment in which sulfur (S) is present as a single element.

12≤Mo (%) +1/2 (%) <16

Cr (%) + 10Mo (%) + 5W (%) ≥140

Satisfy the equation and add a certain amount of Cu.

16≤Mo (%) + 1 / 2W (%) ≤20

Cr (%) + 10Mo (%) + 5W (%) ≥180

It was required to satisfy the equation and to add a certain amount of Cu.

However, the Ni-based alloy according to the above composition has a disadvantage in that the use as a popular corrosion-resistant alloy is limited by requiring a large amount of expensive W, Mo, and Cr, and the effect is limited to a certain case of sour gas. .

Accordingly, the present invention solves and improves the problems of the prior art, thereby exhibiting excellent corrosion resistance under various corrosion atmospheres without using expensive metals such as tungsten, and having Ni-Cr-Fe alloys having high strength and proper elongation. Its purpose is to provide an economical manufacturing method thereof, and in addition, to provide a method for producing an effective corrosion-resistant alloy that can be dissolved in the air by improving the economic efficiency of melting the raw metal in a vacuum state in order to make a special purpose alloy. For the purpose.

Corrosion-resistant alloy of the present invention is added to a small amount of Cu, Ti, Zr, Al, C, V, Ca, Nb or Mo by adding a small amount of Si, Mn with Ni, Cr, Fe as a main component As the paper phase is added, expensive Co, which is added as an essential element in the preparation of nickel-based superheat-resistant alloy, does not use W and excludes its use, and minimizes the content of Mo.

Specifically, the component ratio of the corrosion resistant alloy of the present invention is as follows.

Principal component metal element; Ni 60.01 to 74.48% (weight ratio)

Cr 15.0-28.0%

Fe 1.20-16.0%

Essential component metal element; Si 0.10 to 0.90%

Mn 0.10 to 0.90%

Selected metal element; 0.05 to 2.5% Cu (0.05 to 2.0%)

(2 or more types selected) Ti 0.10 to 1.80% (0.30 to 1.50%)

Zr 0.10 to 0.50% (0.10 to 1.30%)

Al 0.30 to 0.50%

C 0.01 to 0.05% (0.01 to 0.03%)

V 0.10 to 0.50% (0.20 to 0.44%)

Ca 0.01 ~ 0.05% (0.01 ~ 0.03%)

Nb 0.10 to 0.90% (0.30 to 0.80%)

Mo 1.00-9.00% (3.00-6.00%)

Cr is an essential requirement for improving the corrosion resistance and heat resistance of the alloy itself, and when the content is 15 wt% or less with respect to Ni, it does not show an excellent effect on high corrosion resistance, and when it is 30 wt% or more, in terms of price It is disadvantageous.

In addition, Si is added to increase the strength of the alloy and to refine the crystal grains, and also to increase the deoxidation effect during the melting and to improve the fluidity in the molten metal to facilitate the melting operation. However, the addition of more than 1% by weight decreases the ductility to show the brittleness during the rolling process.

Cu is particularly preferably added in an amount of 0.05 to 2.0 parts by weight.

Ti, like Si, acts as a deoxidizer and prevents the formation of bubbles in the casting state, as well as greatly miniaturizing the parent particle, so that the alloy of the present invention exhibits the appropriate ductility required for excellent strength and workability. When added at 1.5% by weight, the properties are particularly excellent.

In addition, Zr exhibits excellent strength by greatly miniaturizing the parent crystal grains with Ti, particularly when added at 0.1-0.3% by weight.

Al acts as a deoxidizer and is a powerful solid solution strengthening element, which is very effective in increasing strength but tends to reduce ductility, so it should be added within the above content range.

In addition, C is added at 0.01-0.05% by weight, but is most preferably added at 0.01-0.03% by weight.

The above V serves to improve the strength by miniaturizing the parent crystal grains, it is most preferably added at 0.20-0.44% by weight, Ca is added to further improve the deoxidation effect during dissolution, 0.01-0.03 Most preferred is the addition by weight.

In addition, it is particularly preferable to add Nb at 0.3-0.8 wt% and Mo at 3.0-6.0 wt%.

All of the components of the present invention described above have a purity of 99%.

Meanwhile, the production method of the present invention for producing the Ni-Cr-Fe alloy as described above is as follows.

That is, the raw metal is dissolved in the air using a high frequency induction furnace in accordance with the above composition ratio. When the temperature of the molten metal reaches about 1500 ° C, the ingot obtained by casting is soaked at 1150 ° C for 1 hour. Hot rolling is then carried out starting at 1500 ° C and rolling to 1000 ° C in 12 steps to achieve a 80% reduction rate. The hot rolled sample is air-cooled in air, and maintained at 1150 ° C for 15 to 30 minutes for homogenization treatment. Subsequently, it is immersed in water or air-cooled and cold-rolled until the final reduction ratio reaches 90%.

The Ni-Cr-Fe alloy of the present invention prepared as described above exhibits high strength and proper elongation due to addition of trace alloy elements and precipitation strengthening by heat treatment. As can be seen from the optical micrograph of the 3 degree, the precipitates are precipitated to enhance the mechanical properties.

Embodiments of the present invention are as follows and the protection scope of the present invention is not limited thereto.

Example 1

After dissolving the metals in the high frequency induction furnace using the composition of Example 1 of Table 1 below, the molten metal was cast using a mold of 50 × 50 × 180 mm when the melt temperature reached 1500 ° C., and the resulting ingot was then heated at 1150 ° C. for 1 hour. After soaking for a while, it was rolled up to 1000 ° C. in 12 steps so that the reduction ratio was 80%. It was then air-cooled in air and held at 1150 ° C. for 30 minutes for homogenization, followed by air cooling.

The alloy of the present invention was prepared by cold rolling until the final reduction ratio reached 90%.

Example 2

An alloy was manufactured in the same manner as in Example 1, using the composition of Example Alloy 2 in Table 1 below.

Example 3

An alloy was manufactured in the same manner as in Example 1, using the composition of Example Alloy 3 in Table 1 below.

Example 4

An alloy was manufactured in the same manner as in Example 1, using the composition of Example 4 of Table 1 below.

Example 5

An alloy was manufactured in the same manner as in Example 1, using the composition of Example 5 of Table 1 below.

Example 6

An alloy was manufactured in the same manner as in Example 1, using the composition of Example Alloy 6 in Table 1 below.

Example 7

An alloy was manufactured in the same manner as in Example 1, using the composition of Example Alloy 7 in Table 1 below.

Composition ratios of the conventional Hastelloy X, Inconel 601 and the alloy used in the above examples are shown in Table 1 below.

Composition of nickel-based corrosion resistant alloy (parts by weight)

TABLE 1

Table 2 compares the tensile properties, ie, mechanical properties, at room temperature (25 ° C.) of the conventional alloy and the alloy of the present invention. It can be seen that the yield strength, which is particularly important in structural materials, is superior to the conventional alloy of the alloy of the present invention. .

In addition, Table 3 shows the corrosion test results of the conventional alloy and the alloy of the present invention as the corrosion rate, the experiment was carried out as follows.

That is, in order to test the corrosion resistance of various acid solutions, the solvent-treated alloy was processed into a cylindrical shape having a diameter of 4 mm and a height of 6 mm and subjected to a needle test in sulfuric acid, hydrochloric acid, nitric acid, and hydrofluoric acid solution, and the test temperature was room temperature. After maintaining for 48 hours, the weight loss was measured to the third decimal place, and the corrosion rate was expressed in mpy (miles per year). Where mpy is given by

myp = 534 × △ W / (A × ρ × t)

Where △ W: weight loss (grams)

A: square inches of specimen

ρ: specimen density (gram / cc)

t: corrosion test time (hours)

Comparison of Tensile Properties

TABLE 2

Metal handbook, 9th ed. vol 3, pp. 210-218

Corrosion test result

TABLE 3

* The weight loss was measured after immersing the specimen in each acid solution at room temperature.

As can be seen from the table, the alloy of Example 2 exhibited excellent corrosion resistance in almost all corrosion atmospheres, such as the alloy of Example 1, particularly excellent castability, such as showing a smooth casting surface and excellent weldability as a result of welding test. It was.

Compared with the alloys of Examples 1 and 2, the alloy of Example 3 was slightly inferior in corrosion resistance and weldability under hydrochloric acid atmosphere, but was excellent in hot and cold rolling properties.

In addition, it can be seen that the alloy of Example 7 greatly improved the corrosion resistance under hydrochloric acid atmosphere by adding an appropriate amount of Mo to the alloy composition of Example 2.

As described above, the highly corrosion-resistant Ni-Cr-Fe-based alloy of the present invention is made of Ni and Cr, including inexpensive Fe, as a main component, instead of using expensive metals (W, etc.), compared to conventional Ni-based corrosion-resistant alloys. It has a very good effect in terms of corrosion resistance, mechanical strength and rollability in the atmosphere.

In addition, in the manufacturing method, the dissolution of the metal raw material can be carried out in the air, not in a vacuum, thereby simplifying the process and saving economic efficiency.

The present invention has a feature that drastically escapes expensive metals used in special alloys, processes under vacuum conditions, etc., and will be very satisfactory to the demand for popular corrosion resistant alloys.

In addition, the corrosion-resistant alloy of the present invention can be processed into a plate, a bar, a wire, a plate, etc., due to the above-described features, using a welding rod of the material composition can be manufactured as a corrosion-resistant container (vessel), etc. The desired shape can be obtained in any form, and also cold working can be performed without undergoing hot working in a casting state, and thus it can be produced as a plate.

Claims (2)

Highly corrosion-resistant Ni-Cr-Fe alloy, which contains Ni 60.01 to 74.48 wt%, Cr 15.0 to 28.0 wt%, Fe 1.20 to 16.0 wt% as a main component, Si 0.10 to 0.90 wt%, Mn 0.10 to 0.90 wt% In addition, 0.05 to 2.5% by weight of Cu, 0.10 to 1.80% by weight, 0.10 to 0.50% by weight of Zr, 0.10 to 0.50% by weight of Al, 0.01 to 0.05% by weight of C, 0.01 to 0.50% by weight of V Highly corrosion-resistant Ni-Cr-Fe alloy, characterized in that the composition is added by selectively adding two or more of%, 0.01 to 0.05% by weight, 0.10 to 0.90% by weight of Nb or 1.00 to 9.00% of Mo. Ni is 60.01 to 74.48% by weight, Cr 15.0 to 28.0% by weight, Fe 1.20 to 16.0% by weight, Si 0.10 to 0.90% by weight, Mn 0.10 to 0.90% by weight as essential components, in addition to Cu 0.05 -2.5 weight%, Ti 0.10-1.80 weight%, Zr 0.10-0.50 weight%, Al 0.30-0.50 weight%, C 0.01-0.05 weight%, V 0.01-0.50 weight%, Ca 0.01-0.05 weight%, Nb 0.10- 2 or more types selected from 0.90% by weight or Mo 1.00 to 9.00% to be dissolved in the air using a high frequency induction furnace; Soaking the ingot obtained by casting when the temperature of the molten metal reaches 1500 ° C. for 1 hour at 1150 ° C .; Hot rolling to obtain a reduction ratio of 80% through 12 steps from 1150 ° C to 1000 ° C; Air-cooling after the hot rolling process and maintaining the solution at 1150 ° C. for 15 to 30 minutes for homogenization treatment; And performing a cold rolling process by air-cooling to form a 90% reduction ratio in order.