JPH06264169A - High-temperature resisting and corrosion resisting ni-cr alloy - Google Patents

Abstract

PURPOSE: To produce an Ni-Cr-Fe alloy excellent in heat resistance and corrosion resistance by formulating specific Percentages of Ni, Cr, Al, Y, Ti, C, Si, Mn, Mg, Ca, Ce, B, Zr, N, Co, and Fe.

CONSTITUTION: An Ni-Cr-Fe alloy, having a composition consisting essentially of, by weight, 55-65% Ni, 19-25% Cr, 1-4.5% Al, 0.045-6.3% Y, 0.15-1% Ti, 0.005-0.5% C, 0.1-1.5% Si, ≤1% Mn, 0.005%, in total, of at least one element selected from Ma, Ca, and Ce, <0.5%, in total of Mg and Ca, <1% Ce, 0.0001-0.1% B. ≤0.5% Zr, 0.0001-0.2% N, ≤10% Co, and the balance Fe with incidental impurities, is prepared. By this method, the Ni-Cr-Fe alloy improved in oxidation resistance at about 1,200°C can be obtained.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to Ni-Cr-Fe alloys, and more particularly to alloys for use in high temperature (1200 ° C) applications.

[0002]

2. Description of the Related Art Ni-Cr such as Inconel alloy 601
-Fe alloys have traditionally been used for general engineering applications requiring heat and corrosion resistance (Inconel is a registered trademark of the Inco Group). Further, Inconel 601 has high temperature oxidation resistance as well as excellent resistance to thermal cycle fatigue. Inconel alloy 601 is commercially used in thermal processing equipment, chemical processing applications, petrochemical applications, pollution control applications and turbine engine components.

Inconel alloy 601 is widely used as a roller alloy for high temperature kilns used for firing ceramic tiles. In high temperature kilns for firing ceramics, the rollers are generally exposed to oxidizing conditions at elevated temperatures from 1000 ° C to 1165 ° C, but at such high temperatures,
Roller alloys tend to gradually deteriorate as they are gradually oxidized. Increasing the temperature to about 1200 ° C unacceptably increases the oxidation and spalling rates.

[0004]

The present invention is 1200 ° C.
The purpose of the present invention is to provide a Ni-Cr-Fe alloy with improved oxidation resistance.

[0005]

According to the present invention, in weight%, nickel 55-65%, chromium 19-25%, aluminum 1-4.5%, yttrium 0.045-0.3%,
Titanium 0.15 to 1%, carbon 0.005 to 0.5%, silicon 0.1 to 1.5%, manganese 0 to 1%, total of magnesium, calcium and / or cerium is at least 0.005%, The total of magnesium and / or calcium is less than 0.5%, cerium is less than 1%, boron is 0.0001 to 0.1%, zirconium is 0.5% or less,
A heat-resistant and corrosion-resistant alloy composed of 0.0001 to 0.1% nitrogen, 10% or less cobalt and the balance iron and associated impurities.

The present invention provides a Ni-Cr-Fe alloy having improved high temperature cyclic oxidation resistance. Nickel-based alloys containing a combination of chromium, yttrium, silicon and aluminum have been found to have significantly improved oxidation resistance at 1200 ° C. A temperature of 1200 ° C. is particularly useful in kilns for firing lead-free frits.

A total of six test Ni-Cr-Fe alloys were cast into 10 kg ingots. The ingot 7 was cast from a commercially available alloy raw material. The chemical composition of the match money is shown in Table 1.
In% by weight. (All compositions herein are in weight percent unless otherwise specified.)

[0008]

[Table 1]

Ingot numbers 1 to 6 are test alloys, and ingot number 7 is a commercially available Inconel alloy 601 alloy. These ingots were machined, smoothed and forged into 50.8 mm round bars at 1140 ° C. Round bar is 1
Annealed at 175 ° C for 30 minutes. A test piece was prepared by machining from a forged rod into a plate having dimensions of about 15 mm × 20 mm × 3 mm. A 3 mm diameter hole was drilled in the plate for mounting the test piece to the jig. All oxidation test pieces are silicon carbide paper 2
Polished to 40 grade finish. After recording the sample size, all specimens were degreased and dried in hot air. The test pieces were heated in a 1200 ° C. air oven for 168 hours and then cooled for 20 minutes to perform a repeated oxidation test. The results of the repeated oxidation test are shown in Table 2.

[0010]

[Table 2]

The above sample numbers correspond to the ingot numbers in Table 1. From the above high temperature experiment, it was found that the composition of the ingot 4 has the best oxidation resistance at 1200 ° C. It has been found that scale integrity increases as the amount of titanium decreases.
It has also been found that a yttrium-rich phase at the alloy / scale interface increases scale adhesion. This is considered to have the effect of changing the oxidation mechanism of the alloy and improving the oxidation resistance. It was found that sample number 4, high in yttrium, provided a tightly adhered scale layer to provide an effective barrier to prevent internal oxidation. Furthermore, it is considered that the high aluminum content of Sample 4 also contributes to the high temperature stability of the oxide scale.

From the above results, a commercially available Ni-Cr-Fe alloy (alloy A) having a composition range shown in Table 3 was manufactured.

[0013]

[Table 3]

According to the invention of alloy A, high temperature (1200 ° C.)
A Ni-Cr-Fe-Al alloy having improved oxidation resistance was obtained. It has been found that the combination of chromium, yttrium, silicon and aluminum significantly improves the oxidation resistance. The improved Ni-Cr-Fe-Al alloy had only a slight reduction in hot ductility compared to the commercially available Inconel alloy 601. A series of test alloys were prepared and analyzed to identify the optimum compositional range for Alloy A.

[0015]

EXAMPLES The present invention will be described below based on examples.
A first series of test alloys having the compositions shown in Table 4 were produced. Each 12.5 kg cast ingot was machined, smoothed and subsequently forged at about 1150 ° C. into a 15 mm thick slab. Each slab was then hot rolled stepwise at about 1150 ° C. to produce a 4 mm thick hot strip. 1 for each sample
It was annealed at 177 ° C. for 30 minutes and air cooled to room temperature. Prior to the oxidation test, the samples were polished with silicon carbide paper to a 240 grade finish, similar to the samples in Table 1. In a first series of repeated oxidation tests, the alloys shown in Table 4 were subjected to a thermal cycle of heating for 20 minutes and cooling for 10 minutes in air. Table 5 shows the obtained weight changes.

[0016]

[Table 4]

[0017]

[Table 5]

The examples shown in Table 5 are 1100 ° C. on average.
A little inferior to alloy 601 in. However, the alloys of the present invention show some improvement upon repeated oxidation at 1200 ° C. It is believed that the results in Table 5 are improved if a stable oxide is formed by an initial oxidation treatment at a temperature of at least 1100 ° C. prior to testing. The alloys of Table 4 were then exposed to hot air for 1 week, followed by room temperature air cooling for 20 minutes. The results of the 1-week cycle test are shown in Table 6.

[0019]

[Table 6]

At a temperature of 1050 ° C., the alloys of the invention show a mixing effect in long-term cycle tests. But 1
At 165 ° C and 1200 ° C, the oxidation resistance is remarkably improved. 1 and 2 show this improvement. The alloy of the present invention initially oxidizes at a higher rate than alloy 601. The advantage over this alloy is the steady low oxidation rate achieved after / during the first week of high temperature exposure. For optimal results, the alloy should be treated for at least 110 hours before use to give a stable deposited oxide.
It should be kept at a temperature of 0 ° C. Oxidative infiltration was also tested on alloys of the invention and alloy 601. The results of the oxidative penetration test are shown in Table 7.

[0021]

[Table 7]

The data in Table 7 show the good resistance of the alloys of the invention to oxide penetration. From the above test,
In order to limit the scope of the alloys of the present invention, the ranges shown in Table 8 were determined.

[0023]

[Table 8]

Next, the function and composition range of alloys and the like will be described. Nickel, in an amount of 55-65%, gives the alloy processability, assemblability and general oxidation resistance. Chromium provides oxidation resistance in an amount of 19-25%. The oxidation resistance is insufficient if the chromium content is less than 19%. The amount of chromium is 25
If it exceeds%, a harmful chromium phase may be formed. Initial tests have shown that the effect of chromium above 20% is neutral and does not contribute to imparting oxidation resistance.

Aluminum is beneficial for its oxidative properties, and it is believed that the increase in aluminum contributes to oxide scale deposition. At least 1% and most preferably at least 2.7% aluminum provides high temperature oxidation resistance. Aluminum is limited to 4.5%, preferably 3.5%, to suppress deleterious hot workability effects. Yttrium helps stabilize the oxide in an amount of at least 0.045%, preferably at least 0.05%. In the samples tested, yttria was not readily observable by light microscopy. An excess of 0.3% yttrium is believed to adversely affect workability and welding properties. Most advantageously, yttrium is limited to 0.07%.

Titanium is added as a reactive element to combine with nitrogen and carbon. Add at least 0.15% titanium to fix the nitrogen. An excess of titanium exceeding 1% adversely affects the oxidation resistance and workability. Iron acts as an inexpensive alternative to nickel.
Most advantageously, at least 10% iron is present to reduce the cost of the alloy. In addition, iron is most advantageously limited to 20 or 18% in order to suppress the degradation of the beneficial properties of nickel.

Carbon is 0.005%, preferably 0.0
An amount of 1% exerts a sufficient particle size adjusting action. The upper limit of carbon is kept at 0.5%, preferably 0.2%, to limit the formation of excess carbides that constrain the useful elements and to suppress grain boundary embrittlement. Silicon is limited to 1.5%, preferably up to 1% to suppress weldability and workability problems. Also, at least 0.1%, and preferably 0.5% of silicon is added to provide oxidation resistance.

Manganese is an impurity which adversely affects the oxidation resistance. Manganese is preferably limited to up to 1%, more preferably up to 0.5%. It is most advantageous to add a total of at least 0.005% magnesium, calcium and / or cerium to improve malleability and deacidification. To minimize adverse effects on weldability and workability, it is advantageous to limit the total amount of magnesium and / or calcium to 0.5%, most favorably 0.2%.

Boron improves malleability in an amount of 0.0001%, preferably 0.001%. To minimize the adverse effects on malleability and weldability, boron should be added at 0.
Limit to 1%. Boron is advantageously limited to 0.05%, most advantageously 0.01% or 0.006%. Zirconium can optionally be added for malleability and particle size control. Zirconium reacts with nitrogen to form nitrides,
This prevents grain growth at high temperatures. To improve weldability and workability, zirconium is preferably present at 0.
Limit to 5%, most preferably to 0.2%.

Nitrogen is added to effectively suppress grain growth. Nitrogen is generally added in a sufficient amount as an impurity in the raw material. At least 0.0001% or 0.
An amount of 001% nitrogen confers resistance to grain growth.
To suppress grain growth, the amount of nitrogen should be at least 0.0.
Most advantageously, it is maintained at 3%. Alternatively, grain growth can be suppressed by adding an annealing step between the deformation steps to limit the energy stored in the alloy. Nitrogen is limited to 0.2% to avoid excess internal oxidation of beneficial elements. Nitrogen is preferably 0.1
%, Most preferably 0.05%.

Cerium can optionally be added as a substitute for magnesium or in an amount up to 1% to provide further oxidation resistance. However, in the chromium, aluminum, silicon and yttrium ranges of the present invention, oxidation resistance does not require cerium. Cobalt is an acceptable impurity in amounts up to 10% and acts as a substitute for nickel. Cobalt is advantageously limited to 5%, with less than 1% being most advantageous. Since cobalt is relatively expensive, it is preferable not to add cobalt.

Copper, molybdenum, niobium, vanadium and tungsten are used in Table 8 to improve the appearance of the alloy.
It is advantageous to maintain within the limits given in. It is most advantageous to keep it at a commercially practical level. Lead, tin, antimony, bismuth, phosphorus, sulfur and oxygen are all incidental impurities and should be kept to the lowest commercially practical levels possible. Most advantageously, the total amount of lead, tin, antimony, bismuth, phosphorus, sulfur and oxygen is kept below 0.1%.

The alloys of the invention were tested and found to have sufficient mechanical properties. Initial welding tests showed a tendency for solidification cracking with increasing yttrium content. However, the alloys of the invention were not tested.
The alloys of the present invention are easily processed into seamless tubes by conventional extrusion or extrusion and cold working techniques. The tubes are then cut into short rollers that are particularly useful in kilns operating at temperatures of about 1200 ° C. The oxide formed at high temperature has extremely high adhesion, and the conventional alloy 601
Less likely to cause ceramic discoloration. Deposit scales are particularly useful for white ceramics.

The statutory provisions set forth specific embodiments of the invention. Of course, it will be apparent to those skilled in the art that variations and modifications are possible within the scope of the invention as indicated by the claims.

[Brief description of drawings]

FIG. 1 shows the relationship between mass change and time of various alloys at 1165 ° C. in an air atmosphere.

FIG. 2 shows the relationship between mass change and time of various alloys at 1200 ° C. in an air atmosphere.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Wai-Yang, Chan Hereford, England-Hampton-Dean, Linden, Lee, Hay, Croft, 2 (72) Inventor Norman, Charles, Far Hereford, England , Chartwell, road, 5

Claims (15)

[Claims] 1. Substantially, by weight, nickel 55-65%, chromium 19-25%, aluminum 1-4.5%, yttrium 0.045-0.3.
%, Titanium 0.15 to 1%, carbon 0.005 to 0.5
%, Silicon 0.1 to 1.5%, manganese 1% or less, total 0.005% of at least one element selected from the group consisting of magnesium, calcium and cerium, total 0.5% of magnesium and calcium. Less than, less than 1% of cerium, 0.0001 to 0.1% of boron, 0.5% or less of zirconium, 0.0001 to 0.2% of nitrogen, 10% or less of cobalt, and the balance consisting of iron and associated impurities. Heat resistant and corrosion resistant alloy. 2. Chromium 19-22%, aluminum 2.5-4.0%, yttrium 0.05-0.1% by weight.
5%, titanium 0.15 to 0.75% and silicon 0.5
Alloy according to claim 1, characterized in that it is ~ 1%. 3. By weight%, carbon 0.01-0.3%, magnesium 0.005-0.2%, boron 0.001-
Alloy according to claim 1, characterized in that it is 0.05% and 0.001-0.1% nitrogen. 4. Iron is less than 20%,
The alloy according to claim 1. 5. Alloy according to claim 1, characterized in that the iron content is 10-18%. 6. Substantially, by weight, 57.5-62.5% nickel, 19-22% chromium,
Aluminum 2.5-4%, Yttrium 0.05-
0.15%, titanium 0.15 to 0.75%, carbon 0.0
1 to 0.3%, silicon 0.5 to 1%, manganese 1% or less, total 0.00 of at least one element selected from the group consisting of magnesium, calcium and cerium.
5%, total magnesium and calcium less than 0.2%, cerium less than 1%, boron 0.001-0.05
%, Zirconium 0.4% or less, cobalt 5% or less, and the balance iron and incidental impurities, and a heat-resistant and corrosion-resistant alloy. 7. By weight%, chromium 19.5-21%, aluminum 2.7-3.5%, yttrium 0.05-
Alloy according to claim 6, characterized in that it is 0.07% and titanium 0.3 to 0.75%. 8. By weight%, carbon 0.05 to 0.15%, magnesium 0.005 to 0.2%, boron 0.001 to
Alloy according to claim 6, characterized in that it is 0.01% and 0.001-0.05% nitrogen. 9. Iron is less than 20%,
The alloy according to claim 6. 10. Alloy according to claim 6, characterized in that the iron content is 10-18%. 11. By weight%, copper 0.5% or less, molybdenum 0.5% or less, niobium 0.3% or less, vanadium 0.1.
% Alloy and 0.1% tungsten or less, The alloy of Claim 6 characterized by the above-mentioned. 12. Substantially, by weight, 57.5-62.5% nickel, 19.5-21 chromium.
%, Aluminum 2.7-3.5%, yttrium 0.
05-0.07%, titanium 0.3-0.75%, iron 10
.About.18%, silicon 0.5 to 1%, manganese 0.5% or less, total 0.00 of at least one element selected from the group consisting of magnesium, calcium and cerium.
5%, less than 0.2% of total of magnesium and calcium, less than 1% of cerium, 0.001-0.01 of boron
%, Zirconium 0 to 0.2%, nitrogen 0.001 to 0.
A heat-resistant and corrosion-resistant alloy, which is characterized by comprising 05%, cobalt 1% or less and incidental impurities. 13. It is characterized by containing copper 0.5% or less, molybdenum 0.5% or less, niobium 0.3% or less, vanadium 0.1% or less, and tungsten 0.01%.
The alloy according to claim 12. 14. Alloy according to claim 12, characterized in that it contains at least 0.1% in total of lead, tin, antimony, bismuth, phosphorus, sulfur and oxygen. 15. Alloy according to claim 12, characterized in that nitrogen is at least 0.03%.