JPH0633206A - Method for heat-treating ni-base alloy - Google Patents

Abstract

PURPOSE:To remarkably reduce the time of aging treatment by subjecting an Ni-base alloy having specified components to solid solution heat treatment at a specified temp. for specified time. CONSTITUTION:The Ni-base alloy contg., by weight, 49 to 58% Ni, 15 to 22% Cr, 4.5 to 5.6% Nb and/or Ta, 2.5 to 3.5% Mo, 0.1 to 1.5% Al and 0.5 to 2.75% Ti, and the balance Fe is subjected to solid solution heat treatment at 950 to 1100 deg.C and is thereafter subjected to aging treatment to 720 to 750 deg.C for 3 to 8hr. The time of the aging treatment can remarkably be reduced compared to the conventional aging treatment for inconel 718 in which the treatment, e.g., of 720 deg.CX8H furnace cooling 620 deg.CX8H air cooling is required, and a whole day should be taken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for Ni-base alloys, and more particularly to a aging treatment method for Ni-base alloys which can obtain desired characteristics by aging treatment for a short time.

[0002]

2. Description of the Related Art Inconel 718 (a trade name of Incoalloys), which is a Ni-based alloy, is known as a heat-resistant and high-strength alloy material. Processing is AMS (Aerospace Material Spe
It has been necessary to carry out a long-time process as is known from crfication). For example, 720 ℃ × 8H
→ Furnace cooling → 620 ° C × 8H → air cooling was required, and it was necessary to spend a whole day for the aging treatment.

[0003]

However, although it is good that the characteristics are improved by performing the heat treatment for a long time in this way, it is a serious problem from the viewpoint of manufacturing cost.

Therefore, the present invention solves the above-mentioned problems of the prior art and provides a heat treatment method for a Ni-base alloy, which has the same characteristics as those of the conventional art and which significantly shortens the time required for the aging treatment. The purpose is to

[0005]

In order to solve the above-mentioned problems, the heat treatment method for the Ni-based alloy of the present invention comprises:
Ni: 49-58%, Cr: 15-22%, Nb and / or Ta: 4.5-5.6%, Mo: 2.5-3.
5%, Al: 0.1 to 1.5%, Ti: 0.5 to 2.7
A method for heat treatment of a Ni-based alloy having 5% and the balance being Fe, wherein the Ni-based alloy is subjected to a solution heat treatment at 950 to 1100 ° C, and then an aging treatment at 720 to 750 ° C for 3 to 8 hours. It is characterized by giving.

Detailed Description of the Invention The Ni-based alloy used in the present invention is a precipitation hardening alloy, and the reason for limiting the composition range as described above is as follows. Hereinafter,% means a weight ratio.

Ti, Nb and / or Ta, and A
1 is a component necessary for precipitation hardening, and in order to obtain high strength at high temperature, Ti: 0.5 to 2.75%, preferably 0.65 to 1.15%, Nb and / or Ta:
4.5-5.6%, preferably 4.75-5.5%, A
1: 0.1 to 1.5%, preferably 0.2 to 0.8% is required. If the content of each component is too small, sufficient strength due to precipitation hardening cannot be obtained.On the other hand, if the content of each component is too large, the deformation resistance during processing becomes too large, resulting in poor workability. Become.

Cr is an element added to improve the oxidation resistance at high temperatures, and the content of Cr is required to be 15 to 22%, preferably 17 to 21%. Content is 15%
If it is less than the above range, the oxidation resistance is poor and the material is lost during use at high temperature. On the other hand, if the content exceeds 22%, workability deteriorates.

Mo is an element added to improve the oxidation resistance, and the content thereof is 2.5 to 3.5%, preferably 2.8 to 3.3%. Its content is 2.5%
If less than 3, the effect of improving heat resistance is small, while on the other hand, 3.
If added in excess of 5%, workability, especially hot workability, deteriorates. Ni is the main component of the Ni-based alloy in the present invention, but its content is 49 to 58%, preferably 50 to 5%.
5%. If the content is less than 49%, the oxidation resistance becomes poor, and if it exceeds 58%, the ductility becomes poor.

The solution heat treatment temperature of the Ni-based alloy having the above composition range is in the range of 950 to 1100 ° C. If the treatment temperature is lower than 950 ° C., the solid solution is insufficient, and the predetermined properties (tensile strength, hardness, etc.) cannot be obtained by the subsequent aging treatment. On the other hand, if the temperature exceeds 1100 ° C., the crystal grain size becomes coarse and the grain boundary becomes brittle. Therefore, the solution heat treatment temperature is set within the above range.

The aging treatment temperature is in the range of 720 to 750 ° C. At processing temperatures below 720 ° C. and above 750 ° C., no improvement in properties can be obtained. The aging treatment time in this temperature range is 3 to 8 hours, preferably 4
~ 8 hours. If the treatment time is less than 3 hours, the characteristics cannot be improved. On the other hand, if the treatment time exceeds 8 hours, the characteristics are not improved.

The Ni-based alloy material produced in this way is
It can be suitably used as a high-strength heat-resistant material for various applications, for example, a heat-resistant spring material.

[0013]

Example An alloy material having the chemical composition shown in Table 1 was manufactured by vacuum induction melting and subjected to cold working, which was hot working, to obtain a plate material having a thickness of 0.2 mm.

[0014] The plate material manufactured as described above was subjected to solution heat treatment at a temperature of 1000 ° C., and then subjected to an aging treatment under the conditions shown in Table 2.

The results of the tensile test and the hardness test of the samples which have been subjected to the aging treatment under the conditions shown in Table 2 are shown in Table 2 and also shown in FIGS. Table 2 shows data of tensile strength (measurement number: 2 times), elongation (measurement number: 2 times), hardness (measurement point: 6 points) under each aging treatment condition. Most of the data is not reliable and is used as a reference value. FIG. 1 is a graph showing the effects of aging temperature and aging time on hardness,
FIG. 2 is a graph showing the influence of the aging temperature and the aging time on the tensile strength.

Table 2 Results of tensile test and hardness test Aging treatment condition Tensile strength Elongation hardness (N / mm ² ) (%) (Hv) Annealed 837 (85.4) 29.4 216 217 216 216 839 (85.6) 28.1 215 214 215 600 ° C × 4H 831 (84.7) 10.3 258 265 263 861 (87.8) 9.1 251 249 260 600 ° C × 8H 828 (84.4) 8.6 291 285 284 940 (95.9) 14.6 266 264 264 650 ° C × 4H 927 (94.5) 12.4 331 342 314 951 (97.0) 11.1 301 327 299 650 ° C × 8H 1047 (106.8) 9.2 360 363 359 1004 (102.4) 8.4 347 356 358 700 ° C x 4H 1034 (106.4) 7.1 404 395 406 1018 (103.8) 4.7 376 377 386 386 700 ° C x 8H 1281 (130.6) 11.0 402 404 415 1178 (120.1) 5.3 392 401 398 720 ℃ × 2H 1189 (121.2) 15.5 390 385 360 1168 (119.1) 16.7 379 368 350 720 ℃ × 3H 1221 (124.5) 16.8 405 393 386 1229 (125.3) 23.3 399 417 394 720 ℃ × 4H 1326 (135.2) 19.7 426 423 435 1303 (132.9) 20.3 428 427 427 720 ℃ 8H 1273 (129.8) 13.0 452 443 427 1285 (131.0) 20.2 463 446 450 750 ℃ × 2H 1224 (124.8) 8.5 413 410 416 1239 (126.3) 17.0 417 418 406 750 ° C x 3H 1284 (130.9) 15.8 413 408 406 1300 (132.6) 14.6 418 418 433 750 ° C × 4H 1262 (138.5) 10.6 439 433 424 1297 (137.7) 12.1 429 436 433 750 ° C × 8H 1333 (137.1) 8.2 444 445 432 1304 (136.6) 9.6 424 427 420 770 ° C x 4H 1199 (122.3) 10.6 394 397 414 1249 (127.4) 12.2 394 403 399 800 ° C x 4H 1126 (114.8) 6.3 348 337 345 1131 (115.3) 5.8 354 351 348 800 ° C x 8H 1120 (114.2) 9.1 367 346 353 1118 (114.0) 9.6 339 353 357 Note 1) The value in () of tensile strength is kgf / mm ² unit.

As is clear from Table 2, FIG. 1 and FIG. 2, by setting the aging treatment condition to 720 to 750 ° C. × 3 to 8H, a material having high tensile strength and high hardness can be obtained, It can be seen that a good product can be obtained.

[0018]

EFFECTS OF THE INVENTION According to the heat treatment method of the present invention, the aging treatment time can be greatly shortened while having the same characteristics as the conventional material, so that the manufacturing cost can be greatly reduced. Its industrial value is great.

[Brief description of drawings]

FIG. 1 is a graph showing the effects of aging temperature and aging time on hardness.

FIG. 2 is a graph showing the effects of aging temperature and aging time on tensile strength.

Claims (1)

[Claims] 1. A weight ratio of Ni: 49 to 58% and Cr: 1
5 to 22%, Nb and / or Ta: 4.5 to 5.6
%, Mo: 2.5 to 3.5%, Al: 0.1 to 1.5
%, Ti: 0.5 to 2.75%, and the balance being Fe, which is a heat treatment method for a Ni-based alloy, wherein the Ni-based alloy is subjected to solution heat treatment at 950 to 1100 ° C., and then 72
A heat treatment method for a Ni-based alloy, which comprises performing an aging treatment at 0 to 750 ° C. for 3 to 8 hours.