JPS61238936A - Ni-base precipitation strengthening type alloy having fine crystal grain - Google Patents

Abstract

PURPOSE:To stably obtain fine crystal grains in a wide temp. range forming solid solution, by precipitating specific amounts of MC-type carbides in an Ni-base precipitation strengthening type alloy containing specific percentage of Cr, Al, Ti, Nb and Ta. CONSTITUTION:In the Ni-base precipitation strengthening type alloy containing, by weight, at least 5-30% Cr, 0.1-7.0% Al, 1-10% of 1 or >=2 kinds among Ti, Nb and Ta, the MC-type carbides are precipitated by 0.5-2.0vol%. Further, Mo, W, Fe, Co, B, Zr, Y, Si, Mn, Hf, Mg, rare earth elements, etc., can be properly added to this alloy. Furthermore, it is preferable that the JIS austenite crystal grain size No. is regulated to 4.0-8.0. In this way, the fine grading of crystal grain size is enabled, so that the Ni-base precipitation strengthening type alloy having superior microstructure, macrostructure and mechanical properties can be easily manufactured.

Description

Detailed Description of the Invention A. Industrial application field The invention has good microstructure with well-organized and refined crystal grains, as well as a well-defined macrostructure with less ta parts. This relates to a heavy type alloy in which Ni base precipitates.

- Conventional technology In general, in alloys and iron J4 materials, the grain size has a large effect on the strength of the material. This is no exception, and in terms of strength and ductility, it is desirable to make the grains as fine as possible.

However, in terms of creep rupture frequency, too fine a grain is not good. Therefore, the ideal Ti crystal grain ratio that fully satisfies all required percentage properties is JIS austenite crystal grain IJ [No. 4.0 to about 8.0.

Conventionally, grain control of Ni-based precipitation-strengthened alloys has been carried out by solution treatment after hot working. In other words, simply applying normal hot working, that is, hot plastic working, does not sufficiently cause recrystallization and the crystal grains remain coarse, or there is often a mixed grain structure in which only the vicinity of the grain boundaries are recrystallized. . For this purpose, sufficient P+ crystals are generated in the solution treatment, and the crystal grains are refined and sized. However, if this solution treatment temperature is on the low temperature side of the normally used one-way range (above the recrystallization temperature, above the intermetallic compound solid solution temperature),
Almost no recrystallization occurs, and the structure is similar to that after hot working. In addition, setting the temperature to a low temperature means that At as a forming element is a strengthening phase.

Ti, Nb, and Ta are not sufficiently dissolved in solid solution, and furthermore, when aging treatment is performed, sufficient precipitation of 2 is not produced, making it impossible to obtain good properties. Therefore, solution treatment was performed at a solution treatment temperature on the high temperature side (above the recrystallization temperature and above the intermetallic compound solid solution temperature) where recrystallization occurs and the generated elements At, T+, and Nb@Ta are sufficiently dissolved. Although recrystallization occurs when this process is carried out, and the grain size is regulated, the crystal grains are larger than those of other grains, and it is often difficult to achieve sufficient mechanical properties.

Problems to be Solved by the Invention As mentioned above, in Ni-based precipitation-strengthened alloys, if only the solution treatment temperature is limited, the grain size varies greatly depending on the temperature, It is difficult to obtain fine crystal grains.

The present invention solves this situation by making it possible to stably control crystal grains into fine, distorted grains even at high solution temperatures, and widening the range of [i! The purpose is to provide a Ni-based precipitation-strengthened alloy with fine crystal grains that is stable in the i1m temperature range.

21 Means for Solving the Problems The present invention is characterized by having at least 5 to 30% of Cr and 0.0% of Al in electrical t%.
In a Ni-based precipitation strengthened alloy containing 1 to 10% of T'*Nb, Ta and one or more of T'*Nb and Ta, the MCfi carbide is 0.5 to 2
By precipitating 0%, the above-mentioned problem is solved.

In addition to the above-mentioned components, the alloy of the present invention also contains Mn, 'vV, F
e, Co.

B, Zr, Y, Si, Mn, Hf, Mg, rare earth elements, etc. can be added as appropriate, and these additions do not essentially have any effect on the present invention.

In addition, as mentioned above, the JIS austenite grain size N
When o is about 4 to 8, the mechanical properties (rip IJ-pull breaking strength) will be good.

Ho, the working solution temperature is noon! (above recrystallization temperature, intermetallic compound #
When grain size is adjusted by increasing the temperature (temperature or higher), the recrystallized grains tend to become very large.

This is because the intermetallic compound that had been suppressing the growth of crystal grains due to the pinning effect is dissolved in solid solution, and the progress of recrystallization is no longer inhibited rapidly.

Therefore, such high temperatures (solid solution of intermetallic compounds @ over
By precipitating another inhibitor instead of the intermetallic compound that can suppress the base length of crystal grains, it becomes possible to control the crystal grains up to a sufficiently high temperature.

MC type carbide is suitable as this suppressor.

In order to maintain fine crystal grains up to a sufficiently high temperature, 0.5% or more of the carbide is required in a total of 8%. Therefore, the lower limit of the hollow type carbide was set at 0.5% by volume. If one-sided carbide is precipitated more than necessary, the carbide will precipitate in a ring shape along the fiber flow, and the mechanical properties in the direction perpendicular to this will significantly deteriorate.

In addition, Ti, Nb, and T, which are elements that form MCu carbides,
ll is an element that forms a reinforcing phase, and as MC type carbide t increases, effective Ti, Nb, and Ta that contribute to strengthening decrease, which is not preferable. Therefore, the upper limit of MC type carbide is set at 2% in the case of high performance.

The general alloy of the present invention is a Ni-based precipitation-strengthened alloy, and generally, Ni-based precipitation-strengthened alloys have a strengthening phase of 0.1 to 10% At, 'ri, and Nb as forming elements.

Contains 1 to 10% of one or more types of Ta.

These Ti, Nb, and Ta each stick to C to form an MC type carbide that is stable even at high temperatures.

Further, Cr has effects such as imparting oxidation resistance and solid solution strengthening, and is required to be present in an amount of 5% or more, but on the other hand, if it exceeds 30%, it is not preferable because it causes instability of the austenite matrix. Therefore, in Ni-based precipitation strengthened alloys, C
r is limited to 5 chill and 30%.

The present invention includes various additional elements as described above in addition to the above-mentioned elements, but the addition of these elements does not essentially have any influence on the present invention.

fart. Example The present invention will be explained in detail below based on Examples.

[Example 1] The Ni-based precipitation strengthened alloys shown in Table g1 were subjected to the following treatments.

1st Cloth fi+ 40 wire square bar heated to 1030°C is forged with a 44 piece pot sumi to a steel square rod and cooled.

(2++11 treated square wood at 990℃.1020
℃, 1030℃.

After holding at each temperature of 1080° C. and 1110° C. for 2 hours, a solid solution treatment is performed by cooling for 9 hours.

FIG. 1 shows the relationship between solution treatment temperature and crystal grain size (2). The amount of MC type carbide (volume) is sample A'
Al at L2.5 α14%, 0.42%, and 0.67%, respectively.

From FIG. 1, sample A5 containing the MC type carbide amount (volume %) of the present invention has a smaller dependence of crystal grain size on solid solution treatment temperature than samples M1 and A2, and is stable up to high temperatures, with crystal grain size of 5I1. ．． You can see that it is thin.

FIG. 2 is a diagram showing the micro a iron (xloo) of samples A1 to A5 when treated at 1080° C., which is a typical hard bath treatment performance of the alloy of this example. This figure also shows that the crystal grains of sample A5 according to the present invention are controlled to be fine and powdery.

[Example 2] Among the solution-treated materials of [Example 1], a sample that had been solution-treated at 1080°C, which is Hongoryu's typical same-bath treatment TML degree, was subjected to air-cooling aging at 700°C for 16 hours. Table 2 shows the results of a tensile test at room temperature after the treatment.

Below margin Table 2 As is clear from Table 2, the crystal grains are fine in the present invention.

Sample 3, which is grain-sized, has approximately the same level of ductility even though the α2 yield strength and tensile strength are improved by 5 K9f/d-15 edge f/- compared to sample t2.

It can be seen from this that excellent mechanical properties can be obtained by making the crystal grains finer and more regulated by the invention.

[Example 5] A 1001 square billet of a Ni-based precipitation-strengthened alloy having the components shown in Table 3 was heated to 1130°C and hot rolled to produce a large piece with a diameter of 11 cm.

FIG. 3 shows the macrostructure of the non-+11 lamp after solution treatment and hot rolling at 1040° C. and 1080° C. for 4 hours, respectively. Sample graves 6 and 7 according to the present invention
Even after solution treatment at 1,040°C and 1,080°C, it has a fine macrostructure with no generation of coarse grains.

In contrast, it can be seen that the crystal grains of sample A4.5 have become coarser due to the solution treatment.

Table 3 [Example 4] The Ni-based precipitation-strengthened alloys having the components shown in Table 4 were subjected to the following treatments.

Table 4 (1) 40. Heated to 1030°C. Distort the square bar fi4
Forged up to 30 square bars at 4% and air cooled.

(2) (1) Square bars after treatment at 920℃, 930℃,
A hardening process is performed in which the material is held at 980° C., 1010° C., and 1040° C. for 1 hour and then air cooled.

FIG. 4 shows the relationship between solution treatment temperature and crystal grain size (2). The MC type carbide fi (volume %) is α11, α45, and α75 for samples 48 and 9.10, respectively.
It is Chi.

From FIG. 4, it can be seen that in this example as well, the sample AIO containing the X-type carbide weight (volume %) of the present invention is stable up to high temperatures and has a 4R fineness.

Effects of the Invention As described above, according to the present invention, the crystal grains of a Ni-based precipitation-strengthened alloy can be easily controlled, the crystal grain size can be set to a value of 1, and the microstructure region and macrostructure can be improved.

A Ni-based precipitation-strengthened alloy with excellent mechanical properties can be easily produced.

[Brief explanation of drawings]

Figure 1 shows the N
Figure 2 shows the relationship between solution temperature and crystal grain size for IC type carbide m (volume %).
i-based analysis 1:t151! 1040° C. and 100° C.li of Ni-based precipitation-strengthened alloys of chemical phenomenon and other examples of the present invention
! Fig. 3 is a microscopic photograph showing the macrometallic structure after the i-bath treatment, and shows the temperature and temperature of the same-bath treatment with MCt1M carbide violet (body + IjI) of a Ni-based precipitation-strengthened alloy according to another embodiment of the present invention. FIG. 3 is a diagram showing the relationship between crystal grain sizes. Graduation l eye diagram usuurasakii otsufuri temperature (26th Ura 3 concave 4th group j concave solid body otsuta ynAhΔ station (C) Procedural amendment (voluntary)

Claims (1)

[Claims] 1. At least 5 to 30% Cr and 0.1 to 30% Al by weight.
7.0%, and 1 to 10% of one or more of Ti, Nb, and Ta, in which 0.5 to 2.0% by volume of MC type carbides are precipitated. A fine-grained Ni-based precipitation strengthened alloy. 2. Ni-based precipitation strengthened alloy has C0.1% or less by weight,
Cr18-21%, Al1.0-2.0%, Ti1.5
The fine crystal grain Ni according to claim 1, characterized in that the balance consists of ~2.5 Ni and unavoidable impurities.
Group precipitation strengthened alloy. 3. Ni-based precipitation strengthened alloy has C0.1% or less by weight,
Cr 14-18%, Al 0.4% or less, Ti 1.5-2
．． 2.5% to 3.5% of Nb+Ta, the balance being Ni and unavoidable impurities. 4. JIS austenite grain size No. 4.0-8.
The fine grained Ni-based precipitation strengthened alloy according to any one of claims 1 to 3, wherein