【発明の詳細な説明】[Detailed description of the invention]
産業上の利用分野
本発明は、高強度・難加工材の成形法、特にそ
の超塑性を利用した成形法に関する。
従来の技術
例えば、ガスタービン発動機工業では、発動機
の設計基準から良好な高温強度及び酸化―腐食抵
抗性をもつ合金の使用が要求される。この要求に
応えて多数の合金が開発、応用され、それによつ
て高温強度への要求は満足されたが、それは一般
に合金の成形性能を犠牲にした上で達成されたも
のであつた。しかしながら、厳密な公差に応じて
成形された複雑な形状の何千個もの部品からなる
ジエツト発動機の製作では、合金の成形性能が、
その有用性の度合を決定する上での主要なフアク
ターとなる。多くの工業では、この成形性能の問
題の解決を、便宜的に合金成分の変更によつて計
ることが可能であるが、ガスタービン発動機用合
金に賦課される関連基準は非常に多数存在するの
で、合金成分を変更するか否かにかかわらず、成
形法自体の改良は必至である。
従来、上述したような高強度・難加工材の超塑
性を利用した成形法として、Gatorizing法が知ら
れている。この方法は、被成形材と成形金型との
温度を等しくする等温成形が必要であり、また高
強度・難加工材は通常1000℃以上に加熱しないと
成形できないので、成形にあたつては、金型の材
料としてこの温度に耐えるTZM（TiとZrを含む
Mo合金）を使用しなければならなかつた。
しかしながら、TZMは高価であるばかりでな
く、高温で酸化され易い欠点を有するので、真空
或いは不活性ガス中で成形しなければならず、こ
のために成形装置全体が大がかりなものとなる欠
点があつた。
発明が解決しようとする問題点
上述の超塑性においては、被成形材の温度を上
昇させるとその伸びは多くなるが、断面縮少率は
低下する。かかる知見に基づき、本発明者らは、
上述の被成形材を温度を徐々に降下させながら引
張ると、断面縮少率がさらに増大し、全伸びが一
定温度で引張り試験をした場合よりもはるかに増
大する現象を見出し、本発明を完成したのであ
る。
即ち、本発明は、高強度・難加工材の温度を適
切に管理することにより、容易に複雑多様な形状
の製品に成形できながら、上述のような高価な金
型材料を必要とせず、しかも真空或いは不活性ガ
ス中での成形に伴う大型の成形装置を使用するこ
となしに成形できる方法を提供するものである。
問題点を解決するための手段
本発明は、超塑性現象発現温度の高温域に加熱
した高強度・難加工材を、その超塑性現象発現温
度内で徐々に温度を下げながら成形することによ
つて、上述の問題点を解決した。
作 用
高強度・難加工材を、その延性が大きい温度範
囲内で徐々に温度を下げながら成形することによ
り、絞り（断面縮少率）が大きくなり、延性も大
きいので、複雑多様な形状の製品に成形できる。
実施例
第１図は高強度・難加工材製の試験片の左半部
を模式的に示すもので、ａ〜ｆはそれぞれ超塑性
の試験片を所定の温度に加熱してその温度で引張
つた状態を示している。この第１図で明らかなよ
うに、高強度・難加工材の試験片は、一定温度で
引張る場合、その温度が高くなるにしたがつて、
伸びが増大するが、ある温度を越えると、即ち温
度がｂの場合よりも高くなると、伸びが減少す
る。つまり、温度が高ければ伸びが大きいとは限
らない。また、ある温度範囲内（ｂ〜ｆ）では、
温度が高くなると、伸びが大きくなるが、絞り即
ち断面減少率が温度の上昇と共に小さくなる。
これを高強度・難加工材としてニツケル基スー
パーアロイの一例であるIN―100（米国ザ・イン
タナシヨナル・ニツケル・カンパニの商品名）の
粉末焼結体（高温静水圧プレス条件：1100℃、
900気圧、1hr）を使用した場合について説明す
る。
表１は、上記IN―100の粉末焼結体を1100℃に
加熱し、70％の加工率で押出した後結晶粒微細化
のために1070℃、１時間の焼なましを施し、これ
を第２図に示す試験片１に加工した後、種々の温
度で10-3／ｓの速度で引張つた場合の結果を示し
たものである。
INDUSTRIAL APPLICATION FIELD The present invention relates to a method of forming a high-strength, difficult-to-process material, and particularly to a method of forming the material using its superplasticity. BACKGROUND OF THE INVENTION For example, in the gas turbine engine industry, engine design standards require the use of alloys with good high temperature strength and oxidation-corrosion resistance. In response to this need, a number of alloys have been developed and applied that have satisfied the high temperature strength requirement, but this has generally been achieved at the expense of the alloy's formability. However, in the construction of jet engines, which consist of thousands of parts of complex shapes formed to exacting tolerances, the forming performance of the alloy is
It is the main factor in determining its degree of usefulness. In many industries, it is possible to solve this formability problem by conveniently changing the alloy composition, but there are a large number of relevant standards imposed on gas turbine engine alloys. Therefore, regardless of whether or not the alloy components are changed, the molding method itself must be improved. Conventionally, the Gatorizing method is known as a forming method that utilizes the superplasticity of the above-mentioned high-strength, difficult-to-process materials. This method requires isothermal forming in which the temperature of the material to be formed and the molding die are equalized, and high-strength, difficult-to-process materials cannot be formed unless they are heated to 1000°C or higher. , TZM (containing Ti and Zr) withstands this temperature as mold material
Mo alloy) had to be used. However, TZM is not only expensive, but also has the drawback of being easily oxidized at high temperatures, so it must be molded in a vacuum or inert gas, which has the drawback that the entire molding equipment becomes large-scale. Ta. Problems to be Solved by the Invention In the above-mentioned superplasticity, when the temperature of the material to be formed is increased, its elongation increases, but the cross-sectional reduction rate decreases. Based on this knowledge, the present inventors
The present invention was completed based on the discovery that when the above-mentioned material to be formed is stretched while the temperature is gradually lowered, the cross-sectional reduction rate further increases and the total elongation increases much more than when a tensile test is conducted at a constant temperature. That's what I did. In other words, the present invention can easily mold products into complex and diverse shapes by appropriately controlling the temperature of high-strength, difficult-to-process materials, without requiring the expensive mold materials mentioned above. The object of the present invention is to provide a method that allows molding without using a large molding device associated with molding in a vacuum or inert gas. Means for Solving the Problems The present invention involves forming a high-strength, difficult-to-work material heated to a high temperature range of the temperature at which the superplastic phenomenon occurs, while gradually lowering the temperature within the temperature at which the superplastic phenomenon occurs. Thus, the above-mentioned problems were solved. Function: By forming high-strength, difficult-to-process materials while gradually lowering the temperature within the temperature range where the material has high ductility, the area of area (section reduction ratio) is increased and the ductility is also large, so complex shapes can be formed. Can be molded into products. Example Figure 1 schematically shows the left half of a test piece made of a high-strength, difficult-to-process material. It shows the ivy condition. As is clear from Figure 1, when a test piece made of a high-strength, difficult-to-process material is pulled at a constant temperature, as the temperature increases,
The elongation increases, but above a certain temperature, ie when the temperature is higher than in case b, the elongation decreases. In other words, higher temperature does not necessarily mean greater elongation. Also, within a certain temperature range (b to f),
As the temperature increases, the elongation increases, but the area reduction, that is, the area reduction rate, decreases as the temperature increases. This is used as a high-strength, difficult-to-process material to produce a powder sintered body of IN-100 (trade name of The International Nickel Company, USA), which is an example of a nickel-based superalloy (high-temperature isostatic pressing conditions: 1100℃,
We will explain the case when using 900 atm, 1 hr). Table 1 shows that the above IN-100 powder sintered body was heated to 1100℃, extruded at a processing rate of 70%, and then annealed at 1070℃ for 1 hour to refine the grains. The results are shown when the specimen 1 shown in FIG. 2 was processed and then stretched at various temperatures at a speed of 10 -3 /s.
【表】
このような実験結果を参照すれば、上記IN―
100を第１図ｂに相当する1100℃から徐々に温度
を下げながら加工するのが有効であり、このよう
な加工を行つた結果、全伸びでは800％以上の値
を得ることができた。
なお、上述の本発明の成形法は、ニツケル基ス
ーパーアロイばかりでなく、チタン合金等の超塑
性材料について適用することができる。
次に、第３図に基づいて本発明の実施例をさら
に具体的に説明する。例えばIN―100の粉末焼結
体よりなる被成形材１０は、約1100℃に加熱され
た後に、適宜の装置によつて金型１１中に押入さ
れる。この金型１１は、周囲に配設した高周波加
熱又は誘導加熱などを行う加熱機構１２によつ
て、成形中に被成形材の温度が著しく降下しない
ように加熱されるが、その加熱温度は800〜900℃
程度でよい。
上述の1100℃に加熱された被成形材１０は、金
型１１内において、その温度を徐々に降下させな
がら押圧される。この場合に、この被成形材１０
の成形が完了する時の温度は、その延性が大きい
範囲である950℃程度にすることは勿論である。
なお、この成形は、上述の鍛造のみに限るもの
ではなく、圧延又は押出しでもよい。
発明の効果
本発明は、超塑性現象発現温度の高温域に加熱
した高強度・難加工材を、その超塑性現象発現温
度内で徐々に温度を下げながら成形することによ
り、高強度・難加工材の成形にあたつて、高価な
TZM合金を使用せず、通常の材料を使用できる
ので、金型が安価にできるばかりでなく、成形を
真空或いは不活性ガス中で行わなくてよいので大
きな設備を必要としない。さらに、本発明の成形
法は、延性が大きい範囲内の温度で成形するの
で、金型へ押入する時の密着性がよく、被成形材
が金型の隅まで達して複雑多様な形状であつても
正確な製品を得ることができる。[Table] If you refer to these experimental results, the above IN-
It is effective to process 100 while gradually lowering the temperature from 1100°C, which corresponds to Figure 1b, and as a result of such processing, we were able to obtain a total elongation of more than 800%. Note that the above-described forming method of the present invention can be applied not only to nickel-based superalloys but also to superplastic materials such as titanium alloys. Next, an embodiment of the present invention will be described in more detail based on FIG. For example, a molded material 10 made of a powder sintered body of IN-100 is heated to about 1100° C. and then forced into a mold 11 by an appropriate device. This mold 11 is heated by a heating mechanism 12 that performs high-frequency heating or induction heating placed around it so that the temperature of the material to be molded does not drop significantly during molding, but the heating temperature is 800°C. ~900℃
A certain amount is enough. The molded material 10 heated to 1100° C. is pressed in the mold 11 while gradually lowering its temperature. In this case, this molded material 10
Of course, the temperature at which the forming is completed is approximately 950°C, which is the range in which the ductility is high. Note that this shaping is not limited to the above-mentioned forging, but may also be rolling or extrusion. Effects of the Invention The present invention produces a high-strength, difficult-to-work material by forming a high-strength, difficult-to-work material that has been heated to a high temperature range of the superplastic phenomenon onset temperature while gradually lowering the temperature within the superplastic phenomenon onset temperature. When forming materials, expensive
Since the TZM alloy is not used and ordinary materials can be used, the mold can be made at low cost, and since the molding does not need to be carried out in a vacuum or inert gas, large equipment is not required. Furthermore, since the molding method of the present invention is molded at a temperature within a range where ductility is high, there is good adhesion when the material is pushed into the mold, and the material to be molded can reach the corners of the mold, making it possible to form complex and diverse shapes. You can also get accurate products.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は、高強度・難加工材製の試験片を種々
の温度で引張つた時の伸びを示す模式的な説明
図、第２図は試験片の正面図、第３図は本発明を
実施する装置の概略図である。
１…試験片、１０…被成形材、１１…金型、１
２…加熱装置。
Figure 1 is a schematic diagram showing the elongation of a test piece made of a high-strength, difficult-to-process material when stretched at various temperatures, Figure 2 is a front view of the test piece, and Figure 3 is a diagram showing the elongation of a test piece made of a high-strength, difficult-to-process material. FIG. 2 is a schematic diagram of the apparatus for implementation. 1...Test piece, 10...Molded material, 11...Mold, 1
2...Heating device.