JPS6274040A - Nickel alloy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a high temperature nickel alloy. The alloy of the present invention exhibits a wide range of excellent properties at high temperatures.
Suitable for a variety of applications. In particular, structural members including tube members for furnaces, receptacles, and various other containers may be cited. For example, thermocouples, thermocouple cables, resistance heating elements, heat-sensitive wires, It can be used in heat-tracing cables, as well as in igniters, rocket nozzles, and many other uses.

A particularly suitable application of the invention is as a sheath material for mineral insulated-metal-armored conductive cables of thermocouples or devices containing thermocouples.

OBJECTS AND EFFECTS OF THE INVENTION The object of the present invention is to provide an alloy with improved high-temperature properties, and which has the following properties.

(1) Excellent corrosion resistance against high temperature gas corrosion. In particular, it has #oxidizing properties under continuous or intermittent constant temperature conditions and circulating temperature conditions. It also has anti-disfiguration properties under a wide range of oxygen partial pressures.

(2) i! I! It has extremely stable properties under continuous or intermittent constant temperature conditions, circulating temperature conditions, and a wide range of oxygen partial pressures. These properties are significantly superior to conventional high-temperature nickel alloys.

(3) High tensile strength and holding power at high temperatures.

(4) High temperature machinability in hot extrusion, etc.
It also has excellent machinability at low temperatures, such as cold drawing, cold upsetting, and pilger rolling.

The alloys of the present invention can be produced by, inter alia, vacuum melting, induced vacuum melting, and similar methods. These methods yield high-quality ingots, which are processed into various shapes using processing techniques.

The alloy of the present invention can be used as cast, as hot-worked, as cold-worked, or as fully annealed. By annealing at temperatures above the minimum recrystallization temperature of these alloys, the properties can be further improved and stabilized. This stabilization treatment is performed especially to stabilize the properties.

(Prior Art) Nickel alloys having some of the above properties are known, or nickel alloys having all of these properties are not known. Conventionally, various stainless steels and Inconel alloys are commonly used as sheath materials for metal-sheathed, mineral-insulated conductive cables. However, these alloys lack one or more of the superior properties possessed by the alloys of the present invention.

The inventor is an Austrian Petty Patent
No. 548519 (1985, 12, 3) and Australian Patent Application No. 41675 (1985,
4, 24), NICRO3IL (14 , 2%
Cr, 1.4%Si) and NISII (4,
4%Si, 0.1%Mg). Although these alloys exhibit excellent corrosion resistance to hot gases and extremely high stability, they have the widest range of applications in gold &
K-Armor 1W4-Insulated cable armor materials lack the excellent high temperature tensile strength required. These applications include the nuclear, aerospace, and electronic industries.

Materials used now or in the future as sheath materials for metal-sheathed, mineral-insulated cables, such as stainless steel, Inconel, Nicolosil, and Nisil, have good gas corrosion resistance, stability, and
It lacks tensile strength and retention.

These excellent properties over a wide range make the alloys of the present invention widely suitable for high temperature applications. Depending on these applications, only one of the advantages of the present invention may be required.

Also, a combination of several may be required. The superior corrosion resistance of the alloys of the present invention to hot gases makes them suitable for load-bearing structural elements in furnaces, retorts, reactors, other heating vessels, gas turbine engines, rocket nozzles, and similar applications. This is important when used as a The ultra-high stability of the alloys of the invention is particularly useful for wires and tubes used in thermocouple thermal elements, conductors, and protective sheaths of metal-sheathed, mineral-insulated construction. This is an important property.

Particularly preferred applications for the alloys of the invention are metal-sheaths for thermocouples, mineral-insulated conductive cables, heating elements, heat-sensitive wires, heat-tracing wires, gas turbine engines and flues, i.e. exploration transducers. , and other uses. In such applications, the excellent high temperature properties of the alloy of the present invention due to its combination of gas corrosion resistance, stability, and high tensile strength are best demonstrated.

In these applications, the preferred combination of high gas corrosion resistance and stability is to use nickel with a composition that maximizes these properties and maintains a single solid solution phase structure. It was found that this can be obtained by using a luchrome-silicon alloy. This single solid solution phase texture range is an important preferred feature of the present invention.

Improvement in high temperature strength can be obtained by adding one or more reinforcing elements in addition to the above basic composition. It is believed that such addition provides the necessary strengthening effect through a crystal lattice modification mechanism suitable for a single solid solution phase structure.

In fact, favorable strengthening effects at high temperatures can be obtained through a number of modified compositions that can be obtained by adding one or more optional strengthening elements to the basic nickel-chromium-silicon lattice structure.

(Example) Table 1 shows the preferred composition range of the present invention. Hereinafter, Tai Deng Ke will be described with reference to the accompanying drawings.

In order to obtain the most favorable properties of the alloy according to the invention,
It is necessary that the microstructure of the alloy consists of only a single equilibrium phase, which is ultimately a solid solution.

The preferred range of nickel-chromium-silicon ternary alloys shown in Table 1 are such single solid solution equilibrium structures. In fact, the addition of preferred reinforcing elements such as molybdenum, tungsten, disbium, tantalum, alone or in combination, is within the solid solubility limit of nickel-chromium-silicon ternary alloys. Therefore, there is no solid solution or second phase of all living compounds; furthermore, the preferred range of alloys of the present invention have sufficient cold ductility to form by hot and cold machining. be able to. Also,
Since the recrystallization temperature of the microscopic structure is about 800° C., even if it is work hardened by cold deformation, it can be easily softened by annealing at a temperature above the above temperature. Furthermore, even if there is a variation in properties in the cross section of the alloy due to compositional non-uniformity in the as-cast structure, this can be easily reduced to a minimum of 3 by homogenization heat treatment.

The alloy composition of the present invention requires careful selection of constituent elements of extremely high purity. It is also necessary to sufficiently control the correct content of each of the five elements by melting and casting techniques. In either case, the effect of each constituent element depends on the effect of other elements, so each element is mutually dependent and exerts a synergistic effect in the entire alloy composition. Generally, when one alloying element is added in an amount exceeding the composition range of the present invention, gas corrosion resistance, stability, and tensile strength all deteriorate at high temperatures.

A single solid solution phase nickel-chromium-silicon alloy containing 9 to 15% Cr and 0.3 to 1.5% Si exhibits relatively high stability in high temperature atmosphere.

The instability of thermoelectromotive force and Seebeck effect at this time is
Not only the exposure temperature and atmospheric oxygen partial pressure, but also the solid solution concentration of chromium and silicon in a nickel base (SPECIF
IC5OLUTE C0NCENTRATION). The highest thermoelectromotive force stability is only possible by choosing the chromium and silicon concentrations in the nickel in an optimal range.

Figure 1 shows the conventional nickel-chromium-silicon alloy most widely used in thermocouple thermal engineering, namely, the temperature of 5°C.
Ni-9,3%C as specified by Erica!・
-0.4%Si KP gold alloy thermoelectric instability is shown.

This instability is shown as the deviation of thermoelectromotive force (microvolts) versus atmospheric exposure time at 1200°C. The same figure also shows the excellent thermoelectromotive force stability of the nickel-chromium-silicon alloy, which falls within the preferred range of the present invention.6For example, the deviation of the thermoelectromotive force of the KP gold alloy after 700 hours is 1ioo°C. , approximately -400 microvolts. In contrast, the alloy of the present invention has a
Figure 2 shows the oxidation degree of the KP gold alloy when exposed for 500e at 1200°C in the atmosphere. It is shown that not only a large amount of scale is generated on the surface of the alloy, but also that internal oxidation has occurred, and a large amount of oxides of the constituent elements chromium and silicon are precipitated into the internal matrix of the alloy. There is. The present inventors believe that this internal oxidation causes a large change in the solid solution concentration of chromium and silicon, and although this concentration change progresses temporarily, KP under the above conditions
I learned that this is the cause of the large instability of gold alloy thermoelectromotive force. Of particular importance, the figure shows that the preferred nickel-chromium-silicon alloy of the present invention has little oxidation as external scale or internal oxidation precipitates. As a result, there is substantially no change in solid solution concentration. This results in extremely high thermoelectric stability. The preferred reinforcing elements added in the present invention, such as molybdenum, tungsten, niobium, and tantalum, may be added alone or in combination, and have no adverse effect on the oxidation resistance of the alloy. Vacuum melted ingots of each alloy were extruded into desired shapes and cut to create specimens. Tensile tests and ductility tests at various temperatures were carried out on a 80mm
The test was carried out using the standard specimen of m). Gauge length is 5.6
5/A, (A is the cross-sectional end of the specimen). In particular, a modified N2w1ck universal testing machine was used to facilitate high temperature testing. For each test l-, up to 0.5% stress resistance, 0,0
The specimen was strained at 0.02 mm/lam/l1 inch. Then, 3.2 ml/win until rupture.
and caused distortion. Ductility was determined by elongation of the specimen between the gauge mark and the reduction in cross-section of the fracture surface.

FIG. 3 shows the tensile strength of the nickel-chromium-silicon alloy of the present invention in a fully annealed state as a function of temperature. The strength of this alloy is sufficient at temperatures above 100°F for many of the general applications described in this invention, but also for nuclear, aerospace, electronic, and general engineering applications. There are many applications in the field for which the strength shown in FIG. 2 is insufficient. The addition of small amounts of one or more of molybdenum, tungsten, niobium, and tantalum to the basic nickel-chromium-silicon alloy of the present invention can significantly increase its strength at high temperatures.

The superior properties of the preferred alloys of the present invention are summarized in Tables 2 and 3.
Shown in the table.

All tested alloys showed significant improvement in high temperature strength relative to the base alloy. Best result is 3.0%Nb?
It is noteworthy that what is obtained when p alone is added.

The strength increase for these alloys is about 25-75%. 3%
Although the Nb alloy exhibits extremely high strength, the ductility is not reduced at all. In fact, it is more ductile than the base alloy.

Table 4 shows other experimental results using Nicolosil as the base alloy. The invention alloy was compared to Inconel-600 and stainless steel 310.

Inconel-600 is about 23% weaker than Nicolosil, and N
About 60% weaker than PX-3. stainless steel 31
0 is about 25% stronger than Nicolosil or about 35% weaker than NPX-3.

Nicolosil is more #oxidizing than stainless steel 310 and more than Inconel-600.

This means that niobium improves the fire resistance of Nilacel-chromium-silicon alloys, especially in low oxygen partial pressure atmospheres.

When a combination of reinforcing elements such as Mo, W, Nb, and Ta are added to the alloy composition of the present invention, as mentioned above, the strength of these elements is 1 (influence L). There is up to 7F conversion. Accordingly, the alloys of the present invention can have a larger range of variation for Mo, W, Nb, and Ta than the preferred compositions shown in Table 1. A second preferred composition of the present invention is as follows: Cr 13.5 to 14.5 (weight%)S
i 1.0-1.5 M g 0.5l1ax.

Ce 0.2wax.

M　　　　　　　　　5. Owax.

W　　　　　1. Oiax.

N　b　　　　　3.0　+max.

T　a　　　　2. Owax.

An important feature of the alloy of the present invention is that the grain size and shape can be controlled so that the grains can be selected in a single heat treatment in which the parameters of temperature and time (relatively short time) are varied with respect to each other. The kinetic process that governs the fluctuations must proceed at a sufficiently fast rate. This is because the uninvented alloy has different uses, and it is desirable or necessary to change the average grain size depending on the use.

FIG. 4 shows that the grain size of the preferred nickel-chromium-silicon alloy of the present invention changes easily with temperature.

Strengthening elements used in the present invention, Mo and W.

Nb and Ta do not significantly inhibit either the increase in recrystallization temperature or the grain growth rate in each alloy example.

The invention is not limited to the above embodiments.

Table 1 Table 4

[Brief explanation of drawings]

Figure 1 shows a 3.3ms thermoelement made of KP gold alloy (Ni-9,3Cr-0,4SL), and a Ni-14,2Cr
2 is a graph showing the fluctuation of thermoelectromotive force when similar thermoelements made of -1,4Si-0,05Mg alloy are left in the atmosphere at 1200°C and 1250″C for a long time in comparison with platinum, respectively. Figures 2 (a), (b) and (c) show KP gold alloy Ni-1.
3.3 with 4,2CF-1,4Si-0-05Mg alloy
It is a micrograph showing the structure of an oxide obtained when a mm-diameter specimen was stirred up in the atmosphere at 1200° C. for 800 hours. Figure 3 shows Ni-14,3Cr-1,4Si-0,”
1 is a graph showing the relationship between ultimate tensile strength and temperature of a 1Mg alloy. Also shown are the tensile strengths of the sample alloys of the present invention shown in Tables 1 and 2. Figure 4 (a), (b), (c) and (d) are Ni-14,
Crystal structure of 3Cr-1,43i-0,1Mg alloy (two-section reduction rate 85% as rolled: original thickness 8cm) and 600°C
, a micrograph (x500) showing the crystal structure after annealing at 800°C and 1000°C for 1 hour. Koji Niibe. t-g,,=,,i 2nd r4 Ca> Figure 2 (C)

Claims (1)

[Claims] 1. 13.5% to 14.5% by weight of chromium and 1.
．． A nickel alloy containing 0% to 1.5% by weight of silicon and further containing any one of molybdenum, tungsten, niobium, and tantalum. 2. A nickel alloy according to claim 1 having the following composition. Cr 13.5-14.5% Si 1.0-1.5% Any one or more of {Mo, W, Nb, Ta} 1.0
~1.5%, 0.5-1.0%, 1.0-3.0%, 1
．． The nickel alloy according to claim 2, wherein the nickel alloy is 0 to 2.0% Ni, balance 3, molybdenum 1.0%, tungsten 0.5%, niobium 1.0%, and tantalum 1.0%. 4. The nickel alloy according to claim 2, which contains 3.0% molybdenum and 1.0% tungsten. 5. Also less than 0.5% magnesium or 0.2%
The nickel alloy according to claim 1, containing the following cerium. 6. Also less than 0.2% magnesium or 0.2%
The nickel alloy according to claim 1, containing the following cerium. 7. A nickel alloy according to claim 5 having the following composition. Cr 13.5-14.5% Si 1.0-1.5% Mg 0.5% Ce 0.2% Mo 5.0% W 1.0% Nb 3.0% Ta 2.0% Ni Balance 8. A nickel alloy according to claim 1 or claim 5 containing 0.1% to 0.20% magnesium. 9. A nickel alloy according to claim 1 or claim 5 containing 0.02% to 0.06% cerium. 10. The nickel alloy of claim 1 or claim 5 containing about 0.015% magnesium. 11. A nickel alloy according to claim 1 or claim 5 containing about 0.04% cerium. 12. The nickel alloy according to any one of claims 1 to 4, containing 0.15% magnesium and 0.04% cerium.