JPS6358897B2 - - Google Patents
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- Publication number
- JPS6358897B2 JPS6358897B2 JP56139439A JP13943981A JPS6358897B2 JP S6358897 B2 JPS6358897 B2 JP S6358897B2 JP 56139439 A JP56139439 A JP 56139439A JP 13943981 A JP13943981 A JP 13943981A JP S6358897 B2 JPS6358897 B2 JP S6358897B2
- Authority
- JP
- Japan
- Prior art keywords
- torr
- sintering
- temperature
- gas
- producing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 claims description 32
- 238000005245 sintering Methods 0.000 claims description 30
- 239000000843 powder Substances 0.000 claims description 23
- 229910000601 superalloy Inorganic materials 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 230000001603 reducing effect Effects 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 8
- 229910045601 alloy Inorganic materials 0.000 claims description 7
- 239000000956 alloy Substances 0.000 claims description 7
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 238000012545 processing Methods 0.000 claims description 5
- 238000005275 alloying Methods 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 241001077660 Molo Species 0.000 claims 1
- 238000000465 moulding Methods 0.000 claims 1
- 239000007789 gas Substances 0.000 description 29
- 230000003647 oxidation Effects 0.000 description 13
- 238000007254 oxidation reaction Methods 0.000 description 13
- 229910052799 carbon Inorganic materials 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 238000005261 decarburization Methods 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000004663 powder metallurgy Methods 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000001513 hot isostatic pressing Methods 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000009924 canning Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009689 gas atomisation Methods 0.000 description 1
- -1 graphite powder Chemical compound 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000009692 water atomization Methods 0.000 description 1
- 230000004584 weight gain Effects 0.000 description 1
- 235000019786 weight gain Nutrition 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
Description
この発明はNi基超合金の粉末冶金法による製
造方法に関するものである。
Ni基超合金はNiを主成分としCr，Mn，Ｗ，
Ｖ，Mo，Nb，Al，Ti，Ｃ，などを合金元素と
して含有する合金で耐熱性、耐酸化性、耐食性な
どに優れた特性を有し、たとえば航空機用ジエツ
トエンジン部品の材料として用いるもので航空機
の高速化にともない益々特性の改善が要求されて
いる。従来この超合金は主として鋳造法により製
造されているが鋳造法による場合高価な材料の歩
留りが悪くコスト高であるのみならず鋳造組織の
粗大化、不純物の介在、成分の偏析などによつて
低サイクル疲労特性が悪化する欠点がある。これ
に対しNi基超合金の粉末を製造して加圧成形し
てのち加熱焼結する粉末冶金法による製品は組織
が微細で低サイクル疲労特性が改善され、また粉
末冶金法本来の特質である材料歩留りの良さによ
りコストが低く今後の部品製造方法として発展が
期待されている。
粉末冶金法は１種または２種以上の原料金属粉
末を混合して加圧成形して圧粉体としこれを焼結
する。焼結は圧粉体を炉内で加熱昇温し、金属粉
末の溶融点以下の温度で一定時間保持して粉末相
互の熱的接合および金属の相互拡散によつて粉末
を結合して強固な固体とし、これを冷却して炉外
に取り出す工程である。この場合金属粉末の表面
についた吸着ガスを除去し、加熱中の酸化、脱
炭、浸炭などを防止するため真空、窒素（N2）
ガス、水素（H2）ガス、アンモニア分解ガス、
吸熱性変成ガスなどを炉内雰囲気として焼結が行
われている。しかしNi基超合金は単に上記雰囲
気中で普通の方法で焼結しても良好な焼結体を得
ることができない。
すなわちNi基超合金は易酸化性元素、すなわ
ち第１図に示すように1000℃における酸化物標準
生成エネルギーが110kcal／ｇmoleO2以上である
Cr，Mn，Ｖ，Si，Ti，Al，Nb，Taなどの元素
を含み、したがつてそれらの酸化物が焼結体内に
未還元のまま残留すると機械的性質、耐食性、耐
酸化性がそこなわれる。またNi基合金は耐食性
などを改善するため炭素成分を有せしめる場合が
多い。ところが従来用いられている雰囲気におい
て、真空、窒素（N2）ガスなどの中性雰囲気は
合金粉末の吸着ガスを除去することはできるが還
元性を有しない吸熱性変成ガスも還元力が弱く
Cr，Mn，Si，Tiなどの易酸化性元素の酸化物を
還元することはできない。一方水素（H2）ガス、
アンモニア分解ガスは還元力は強いが酸化物の還
元により生じた水分が混ざると脱炭反応を生ずる
ので炭素を含む製品には適用し難いからである。
この欠点に対し現在は回転電極法あるいはガスア
トマイズ法などによる高純度で100ppm以下の極
低酸素レベルの粉末を用い、さらに焼結体を熱間
静圧成形のような熱間加工を加えて所望の特性を
得るようにしているがコストが非常に高くなる現
状である。
本発明者は昭和56年特許願第56531号（特開昭
57−171644号）としてCo基焼結超合金の製造方
法について特許出願を行つているが、その後鋭意
試験研究の結果同様の方法がNi基焼結超合金の
製造方法としても同様に効果があることを見出し
本発明をなしたものである。
本発明は上記問題にかんがみ、易酸化性元素、
特に1000℃における酸化物標準生成自由エネルギ
ーが110kcal／moleO2以上の元素を含む原料金属
粉末の焼結工程において、脱炭、浸炭が生ずるこ
となく、上記元素の酸化物の還元を十分に行い得
るNi基焼結超合金の新規製造法を提供するもの
であり、その特徴とするところは減圧下の焼結工
程の１部または全部において炉内圧力を約0.2〜
500Torrに調節しつつ還元性ガスを導入すること
を特徴とするものである。
焼結工程に導入される還元性ガスとしてはCO
またはH2ガスが好ましく用いられる。
焼結工程は一般に真空排気下に室温から焼結温
度まで加熱する昇温過程、焼結温度に保持する過
程および焼結温度から室温まで降温させる冷却過
程からなるが、本発明においては昇温、焼結およ
び冷却の過程における焼結の進行に応じて上記還
元性ガスを適宜導入して炉内ガス圧を適当に調節
する。これにより脱炭、浸炭および上記易酸化性
元素の焼結中の酸化を防ぐとともに、該酸化物の
還元、合金化を促進することができる。
本発明においては室温からの昇温過程で温度
800〜900℃に到るまでの間を10-1Torr以下に真
空排気し、該温度から焼結温度に到るまでの間を
COガスを導入して炉内圧を0.2〜500Torrに調節
すると共に焼結温度においては10-2Torr以下の
真空に保持して所定の焼結を行わしめる。冷却過
程は炉内圧を10-2Torr以下に保持したまま、も
しくは還元性ガスを導入して0.2〜500Torrに調
節しつつ室温までに冷却するのが望ましい。
上記昇温過程での真空排気は原料粉末の吸着ガ
スの除去を目的とするもので、上記のように
10-1Torr以下とすることにより吸着ガスの十分
な除去が行われる。
また温度800〜900℃から焼結温度に到るまでの
間にCOガスを導入して炉内のCOガス分圧を高め
ることにより、下式
MO＋CO→Ｍ＋CO2
〔式中、MOは金属（Ｍ）の酸化物を表わす〕
により酸化物の還元が生起する。この反応を前記
のように0.2〜500Torrの減圧下で行うことによ
り、常圧下で還元困難なMn，Cr，Si，Al，Ｖ，
Ti，等の酸化物が還元され、次の焼結温度にお
いて10-2Torr以下の高真空下で行う焼結が著し
く促進される。この場合、0.2Torr未満ではCO圧
力が低すぎるので脱炭が生じ且つ充分な還元がで
きない。また500Torrを越えると逆に浸炭が起こ
るので好ましくない。すなわち0.2〜500Torrの
COガス雰囲気とした場合に浸炭、脱炭が生ぜず
且つ金属酸化物の還元、金属化が十分行われて清
浄度が高く密度の高い焼結製品を得ることができ
る。焼結温度は例えば1200〜1350℃に調節する。
冷却工程では酸化を防止するため10-2Torr以下
あるいは再び0.2〜500Torrの圧力で還元性ガス
を導入しつつ室温まで冷却する。
かくして得られる焼結体は酸化物が十分に還
元・合金化し密度も高くNi基超合金としての本
来の特性である耐食性、耐熱性等にすぐれ、かつ
後記実施例にも示されるように高い機械的性質お
よび耐酸化性等を備えるものである。
本発明では原料金属粉末の酸化物の還元が十分
に行われるので原料粉末はガスアトマイズ粉など
の高純度のものである必要はなく比較的酸素レベ
ルの高い粉末であつてもよい。
Ni基超合金においては強度、耐熱性の向上の
ため炭素を含ましめる場合が多いが本発明におい
て還元性ガスとしてCOガスを用いると脱炭が生
じないので炭素量の制御が容易にできる。
一般に炭素を含む合金粉末は硬度が高く加圧成
形時の圧粉体密度は70％以下と小さく、焼結時に
大きな収縮をともない焼結体の寸法精度が悪い欠
点がある。この場合炭素を含まない合金粉末に所
要量の炭素たとえば黒鉛粉末を混合して成形する
と圧粉体の密度は約10％向上させることができ、
これを焼結すると好ましい結果が得られる。
本発明の焼結法によれば易酸化性の金属酸化物
は還元され金属の清浄度が高いので拡散が十分行
われ密度が従来方法に比し非常に高い焼結体が得
られるが、一般に材質特性を良好に維持するには
相対密度95％以上にすることが好ましい。このた
め焼結体をさらに熱間静水圧加工することが好ま
しい。
以下本発明の実施例について説明する。
実施例 １
水アトマイズ法で製造した下記組成のNi基合
金粉末(A)〜(D)（いずれも−150メツシユ）をプレ
スにより圧粉成形して密度68〜70％の圧粉体とな
し、これを本発明法により焼結した。一方、比較
として上記と同じ組成の各粉末の圧粉体を従来法
により焼結した。それぞれの焼結条件は第１表に
示す通りである。
粉末(A)：Ni−15％Cr−19％Co−５％Mo−3.3
％Ti−4.3％Al−0.07％Ｃ
粉末(B)：Ni−13％Cr−４％Mo−2.2％Nb−0.8
％Ti−6.1％Al−0.06％Ｃ
粉末(C)：Ni−19％Cr−11％Co−10％Mo−3.2
％Ti−1.5％Al−0.06％Ｃ
粉末(D)：Ni−16％Cr−17％Mo−４％Ｗ−5.5
％Fe−0.06％Ｃ
This invention relates to a method for producing a Ni-based superalloy using a powder metallurgy method. Ni-based superalloys are mainly composed of Ni, Cr, Mn, W,
Alloys containing V, Mo, Nb, Al, Ti, C, etc. as alloying elements and have excellent properties such as heat resistance, oxidation resistance, and corrosion resistance, and are used as materials for aircraft jet engine parts, for example. As aircraft speeds increase, improvements in characteristics are increasingly required. Conventionally, this superalloy has been mainly produced by casting, but casting does not only result in poor yields of expensive materials and high costs, but also results in poor performance due to coarsening of the cast structure, inclusion of impurities, and segregation of components. It has the disadvantage of deteriorating cycle fatigue characteristics. On the other hand, products made using the powder metallurgy method, in which Ni-based superalloy powder is produced, pressure-formed, and then heated and sintered, have a fine structure and improved low-cycle fatigue properties, which are the original characteristics of the powder metallurgy method. It is expected to be developed as a future component manufacturing method due to its low cost due to its high material yield. In the powder metallurgy method, one or more raw metal powders are mixed and pressure-molded to form a green compact, which is then sintered. In sintering, the compacted powder is heated in a furnace and kept at a temperature below the melting point of the metal powder for a certain period of time to bond the powders together through thermal bonding of the powders and mutual diffusion of the metals, making them strong. This is the process of turning it into a solid, cooling it, and taking it out of the furnace. In this case, vacuum, nitrogen (N 2 ) is used to remove adsorbed gas on the surface of the metal powder and prevent oxidation, decarburization, carburization, etc. during heating.
gas, hydrogen (H 2 ) gas, ammonia decomposition gas,
Sintering is performed using an endothermic modified gas or the like as the furnace atmosphere. However, a good sintered body cannot be obtained from a Ni-based superalloy simply by sintering it in the above-mentioned atmosphere using an ordinary method. In other words, Ni-based superalloys are easily oxidizable elements, that is, as shown in Figure 1, the standard oxide formation energy at 1000°C is 110 kcal/gmoleO 2 or more.
Contains elements such as Cr, Mn, V, Si, Ti, Al, Nb, Ta, etc. Therefore, if their oxides remain unreduced in the sintered body, mechanical properties, corrosion resistance, and oxidation resistance will deteriorate. be called. Further, Ni-based alloys often contain carbon components to improve corrosion resistance. However, in conventional atmospheres, neutral atmospheres such as vacuum and nitrogen (N 2 gas) can remove adsorbed gases of alloy powder, but endothermic metamorphosed gases that do not have reducing properties also have weak reducing power.
Oxides of easily oxidizable elements such as Cr, Mn, Si, and Ti cannot be reduced. On the other hand, hydrogen (H 2 ) gas,
This is because ammonia decomposition gas has a strong reducing power, but when mixed with water produced by reduction of oxides, a decarburization reaction occurs, making it difficult to apply to products containing carbon.
To address this drawback, currently we use powder with high purity and an extremely low oxygen level of 100 ppm or less using the rotating electrode method or gas atomization method, and further heat processing such as hot isostatic pressing of the sintered body to obtain the desired shape. Although efforts are being made to obtain these characteristics, the cost is currently extremely high. The inventor of the present invention filed Patent Application No. 56531 filed in 1982
No. 57-171644), we have filed a patent application for a method for producing a Co-based sintered superalloy, but after extensive testing and research, we found that the same method is equally effective as a method for producing a Ni-based sintered superalloy. The present invention was made based on this discovery. In view of the above problems, the present invention provides an easily oxidizable element,
In particular, in the sintering process of raw metal powder containing elements with an oxide standard free energy of formation at 1000°C of 110 kcal/moleO 2 or more, the oxides of the above elements can be sufficiently reduced without decarburization or carburization. This provides a new method for producing Ni-based sintered superalloys, which is characterized by reducing the furnace pressure to approximately 0.2 to 0.2 in part or all of the sintering process under reduced pressure.
This method is characterized by introducing reducing gas while adjusting the pressure to 500 Torr. CO is the reducing gas introduced into the sintering process.
Or H 2 gas is preferably used. The sintering process generally consists of a temperature raising process in which the temperature is heated from room temperature to the sintering temperature under vacuum evacuation, a process in which the temperature is maintained at the sintering temperature, and a cooling process in which the temperature is lowered from the sintering temperature to the room temperature. According to the progress of sintering in the sintering and cooling process, the above-mentioned reducing gas is introduced as appropriate to appropriately adjust the gas pressure in the furnace. This can prevent decarburization, carburization, and oxidation of the easily oxidizable elements during sintering, as well as promote reduction and alloying of the oxides. In the present invention, the temperature is
Evacuate to 10 -1 Torr or less until the temperature reaches 800 to 900℃, and from that temperature to the sintering temperature.
The internal pressure of the furnace is adjusted to 0.2 to 500 Torr by introducing CO gas, and the sintering temperature is maintained at a vacuum of 10 -2 Torr or less to carry out the desired sintering. In the cooling process, it is preferable to cool the furnace to room temperature while maintaining the internal pressure at 10 -2 Torr or less, or by introducing a reducing gas to adjust it to 0.2 to 500 Torr. The purpose of vacuum evacuation during the temperature raising process is to remove adsorbed gas from the raw material powder, and as mentioned above,
Adsorbed gas can be sufficiently removed by setting the pressure to 10 -1 Torr or less. In addition, by introducing CO gas from the temperature of 800 to 900℃ to the sintering temperature to increase the partial pressure of CO gas in the furnace, the following formula MO + CO → M + CO 2 [In the formula, MO is the metal (M ) represents the oxide of] The reduction of the oxide occurs. By carrying out this reaction under reduced pressure of 0.2 to 500 Torr as described above, Mn, Cr, Si, Al, V, which is difficult to reduce under normal pressure,
Oxides such as Ti are reduced, and the next sintering temperature, which is performed under a high vacuum of 10 -2 Torr or less, is significantly accelerated. In this case, if the CO pressure is less than 0.2 Torr, decarburization occurs and sufficient reduction cannot be achieved because the CO pressure is too low. Moreover, if it exceeds 500 Torr, carburization will occur, which is not preferable. i.e. 0.2~500Torr
When a CO gas atmosphere is used, carburization and decarburization do not occur, metal oxides are sufficiently reduced and metallized, and a sintered product with high cleanliness and high density can be obtained. The sintering temperature is adjusted to, for example, 1200 to 1350°C.
In the cooling step, in order to prevent oxidation, a reducing gas is introduced at a pressure of 10 -2 Torr or less, or again from 0.2 to 500 Torr, and cooled to room temperature. The sintered body thus obtained has oxides sufficiently reduced and alloyed, has a high density, has excellent corrosion resistance and heat resistance, etc., which are the inherent characteristics of a Ni-based superalloy, and is highly mechanically resistant as shown in the examples below. It has chemical properties, oxidation resistance, etc. In the present invention, since the oxide of the raw metal powder is sufficiently reduced, the raw material powder does not need to be of high purity such as gas atomized powder, and may be a powder with a relatively high oxygen level. Ni-based superalloys often contain carbon to improve strength and heat resistance, but in the present invention, when CO gas is used as the reducing gas, decarburization does not occur, so the amount of carbon can be easily controlled. In general, carbon-containing alloy powders have high hardness, have a low green compact density of 70% or less when compacted, and suffer from large shrinkage during sintering, resulting in poor dimensional accuracy of the sintered compact. In this case, if the required amount of carbon, such as graphite powder, is mixed with carbon-free alloy powder and compacted, the density of the green compact can be improved by about 10%.
Favorable results can be obtained by sintering this. According to the sintering method of the present invention, easily oxidizable metal oxides are reduced and the purity of the metal is high, so that diffusion is sufficient and a sintered body with a much higher density than that of conventional methods can be obtained. In order to maintain good material properties, the relative density is preferably 95% or more. For this reason, it is preferable to further subject the sintered body to hot isostatic processing. Examples of the present invention will be described below. Example 1 Ni-based alloy powders (A) to (D) (all -150 mesh) produced by the water atomization method and having the following compositions were compacted using a press to form a green compact with a density of 68 to 70%, This was sintered by the method of the present invention. On the other hand, for comparison, compacts of each powder having the same composition as above were sintered using a conventional method. The sintering conditions for each are shown in Table 1. Powder (A): Ni-15%Cr-19%Co-5%Mo-3.3
%Ti-4.3%Al-0.07%C Powder (B): Ni-13%Cr-4%Mo-2.2%Nb-0.8
%Ti-6.1%Al-0.06%C Powder (C): Ni-19%Cr-11%Co-10%Mo-3.2
%Ti-1.5%Al-0.06%C Powder (D): Ni-16%Cr-17%Mo-4%W-5.5
%Fe−0.06%C
【表】
上記各方法により得られた焼結体(A)〜(D)の機械
的性質および耐酸化性を第２表に示す。但し耐酸
化性は大気中1000℃で５時間保持する加熱試験に
おける酸化増量の値を示すものである。[Table] Table 2 shows the mechanical properties and oxidation resistance of the sintered bodies (A) to (D) obtained by each of the above methods. However, oxidation resistance indicates the value of oxidation weight gain in a heating test held at 1000°C in the atmosphere for 5 hours.
【表】
第２表に示すように本発明法によつて焼結した
焼結体は従来法のものに比し密度が高く緻密であ
り、抗折強度や耐酸化性もすぐれている。
また粉末Ｃの圧粉体を用いて第１表の本発明法
の欄において、1200〜1350℃→室温とする冷却工
程を0.2〜500Torrの範囲のCOガスおよびH2ガス
雰囲気で行う実験を行つた。
製造された焼結体は、いずれも相対密度97％、
抵抗強度97Kg／mm2程度で大差はなかつた。
即ち従来法（第２表参照）の焼結体に比し優れ
ていることが分かつた。
実施例 ２
実施例１で得られた本発明法による各焼結体を
1150℃で圧力2000Kg／cm2の熱間静水圧加工を施し
た。得られた製品の機械的性質と耐酸化性を第３
表に示す。この場合熱間静水圧加工はキヤニイン
グ無しで行つた。[Table] As shown in Table 2, the sintered body sintered by the method of the present invention has a higher density and is denser than that of the conventional method, and has excellent bending strength and oxidation resistance. In addition, in the column of the method of the present invention in Table 1, using a green compact of powder C, an experiment was conducted in which the cooling step from 1200 to 1350°C to room temperature was performed in a CO gas and H 2 gas atmosphere in the range of 0.2 to 500 Torr. Ivy. The manufactured sintered bodies all have a relative density of 97%,
The resistance strength was around 97Kg/ mm2 , with no significant difference. That is, it was found to be superior to the sintered body produced by the conventional method (see Table 2). Example 2 Each sintered body obtained by the method of the present invention obtained in Example 1 was
Hot isostatic processing was performed at 1150°C and a pressure of 2000 kg/cm 2 . The mechanical properties and oxidation resistance of the obtained product were
Shown in the table. In this case, hot isostatic processing was performed without canning.
【表】
上記結果から熱間静水圧加工により焼結体は著
しく高密度化するとともに強度、耐酸化性も大巾
に向上することがわかる。
実施例 ３
実施例１の粉末(C)を用いてプレスにより圧粉成
形して密度68〜70％の圧粉体とし、この圧粉体を
以下の条件で焼結した。
室温→800℃ 真空 10-2Torr
800℃→1250℃ CO 1.0Torr
1200℃（0.5時間保持） 真空 10-4Torr
1200℃→室温 CO 400Torr
得られた焼結体は相対密度98.0％、抗折強度95
Kg／mm2であつた。
さらに他の条件を同じで冷却工程を400Torrの
H2ガス雰囲気として焼結体を作成した。焼結体
の相対密度は95％、抗折強度は96Kg／mm2であつ
た。
いずれの場合にも従来法の焼結体に比し優れた
焼結体が得られることが分かつた。
以上詳しく説明したように本発明方法による
Ni基焼結超合金は焼結中に金属酸化物の還元が
十分に行われ、焼結性が改善されるため、製品の
清浄度が高く（すなわち非金属介在物などが少
い。）、焼結で高密度が得られる。このため従来の
焼結品に比し機械的性質、耐食性、耐酸化性等の
特性が著しく改善され、本発明方法は径済的な耐
熱、耐食部品の製造方法として極めて有効な方法
である。[Table] From the above results, it can be seen that hot isostatic pressing significantly increases the density of the sintered body, and also greatly improves its strength and oxidation resistance. Example 3 The powder (C) of Example 1 was compacted using a press to obtain a compact having a density of 68 to 70%, and this compact was sintered under the following conditions. Room temperature→800℃ Vacuum 10 -2 Torr 800℃→1250℃ CO 1.0Torr 1200℃ (held for 0.5 hours) Vacuum 10 -4 Torr 1200℃→Room temperature CO 400Torr The obtained sintered body has a relative density of 98.0% and a bending strength of 95
It was Kg/ mm2 . Furthermore, the cooling process was set to 400 Torr under the same conditions.
A sintered body was created in an H 2 gas atmosphere. The relative density of the sintered body was 95%, and the bending strength was 96 Kg/mm 2 . In either case, it was found that a sintered body superior to that of the conventional method could be obtained. As explained in detail above, according to the method of the present invention
In Ni-based sintered superalloys, metal oxides are sufficiently reduced during sintering, improving sinterability, resulting in products with high cleanliness (i.e., fewer non-metallic inclusions, etc.). High density can be obtained by sintering. Therefore, properties such as mechanical properties, corrosion resistance, and oxidation resistance are significantly improved compared to conventional sintered products, and the method of the present invention is extremely effective as an economical method for manufacturing heat-resistant and corrosion-resistant parts.
第１図は各種元素の酸化物標準生成自由エネル
ギーを示すグラフである。
FIG. 1 is a graph showing the standard free energy of formation of oxides of various elements.
Claims (1)
ーが110kcal／molO2以上の合金元素を一種また
は二種以上含むNi基焼結超合金の製造において、
減圧下の焼結工程が、10-1Torr以下の真空中で
室温より800〜900℃までに昇温し、該温度から焼
結温度まで0.2〜500Torrの炉内圧に保持しなが
らCOガスを導入し、焼結温度において10-2Torr
以下の真空中で焼結することを特徴とするNi基
焼結超合金の製造方法。 ２ 焼結温度から室温まで10-2Torr以下の真空
あるいは0.2〜500Torrの還元性ガス雰囲気中で
冷却することを特徴とする特許請求の範囲第１項
記載のNi基焼結超合金の製造方法。 ３ 合金元素がCr，Mn，Si，Ｂ，Al，Tiである
ことを特徴とする特許請求の範囲第１項もしくは
第２項記載のNi基焼結超合金の製造方法。 ４ 炭素を含まない合金粉末と黒鉛粉末を混合し
て加圧成形した圧粉体をCOガスを還元性ガスと
して焼結することを特徴とする特許請求の範囲第
１項乃至第３項いずれかに記載のNi基焼結超合
金の製造方法。 ５ 焼結体に熱間静水圧加工をほどこすことを特
徴とする特許請求の範囲第１項乃至第４項いずれ
かに記載のNi基焼結超合金の製造方法。[Claims] 1. In the production of a Ni-based sintered superalloy containing one or more alloying elements having an oxide standard free energy of formation at 1000°C of 110 kcal/molO 2 or more,
The sintering process under reduced pressure involves raising the temperature from room temperature to 800 to 900℃ in a vacuum of 10 -1 Torr or less, and introducing CO gas while maintaining the furnace pressure from this temperature to the sintering temperature at 0.2 to 500 Torr. and 10 -2 Torr at the sintering temperature
A method for producing a Ni-based sintered superalloy, which is characterized by sintering in a vacuum as described below. 2. A method for producing a Ni-based sintered superalloy according to claim 1, which comprises cooling from the sintering temperature to room temperature in a vacuum of 10 -2 Torr or less or in a reducing gas atmosphere of 0.2 to 500 Torr. . 3. The method for producing a Ni-based sintered superalloy according to claim 1 or 2, wherein the alloying elements are Cr, Mn, Si, B, Al, and Ti. 4. Any one of claims 1 to 3, characterized in that a green compact obtained by mixing and press-molding carbon-free alloy powder and graphite powder is sintered using CO gas as a reducing gas. A method for producing a Ni-based sintered superalloy as described in . 5. A method for producing a Ni-based sintered superalloy according to any one of claims 1 to 4, which comprises subjecting the sintered body to hot isostatic processing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13943981A JPS5839704A (en) | 1981-09-03 | 1981-09-03 | Production of ni-base sintered hard alloy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13943981A JPS5839704A (en) | 1981-09-03 | 1981-09-03 | Production of ni-base sintered hard alloy |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5839704A JPS5839704A (en) | 1983-03-08 |
| JPS6358897B2 true JPS6358897B2 (en) | 1988-11-17 |
Family
ID=15245217
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13943981A Granted JPS5839704A (en) | 1981-09-03 | 1981-09-03 | Production of ni-base sintered hard alloy |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5839704A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6029406A (en) * | 1983-07-27 | 1985-02-14 | Tohoku Metal Ind Ltd | Manufacture of sintered body |
| JPS6086224A (en) * | 1983-10-17 | 1985-05-15 | Toshiba Corp | Preparation of abrasion resistant sintered alloy |
| FR2888141B1 (en) * | 2005-07-07 | 2008-08-29 | Onera (Off Nat Aerospatiale) | METHOD FOR PRESSURE-FREE SINKING OF METAL ALLOYS; APPLICATION TO THE MANUFACTURE OF HOLLOW SPHERES |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS49114609A (en) * | 1973-03-07 | 1974-11-01 | ||
| JPS51139508A (en) * | 1975-04-30 | 1976-12-01 | Jieimuzu Dein Richiyaado | Method of producing metallic product from metallic powder |
-
1981
- 1981-09-03 JP JP13943981A patent/JPS5839704A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS49114609A (en) * | 1973-03-07 | 1974-11-01 | ||
| JPS51139508A (en) * | 1975-04-30 | 1976-12-01 | Jieimuzu Dein Richiyaado | Method of producing metallic product from metallic powder |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5839704A (en) | 1983-03-08 |
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