Development of a Die Material for Isothermal Forging of Superalloys in Air
| Autor: | Takehiro Ohno, Rikixo Watanabe, Toshiaki Nonomura |
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| Rok vydání: | 1987 |
| Předmět: | |
| Zdroj: | Transactions of the Iron and Steel Institute of Japan. 27:34-41 |
| ISSN: | 1881-1183 0021-1583 |
| Popis: | In isothermal forging, since the die is heated as well as the workpiece, high-temperature strength is essentially required for the die material. In particular, isothermal forging of superalloys is carried out at high temperature ranging 1000-1100°C, thus a molybdenum-base alloy, TZM, is generally used as a die material. Although TZM has good high-temperature strength, its oxidation resistance is very poor at above 600°C, therefore, forging must be done in vacuum or inert-gas atmosphere.If there is a die material having both enough strength and oxidation resistance at around 1000-1100°C, isothermal forging of superalloys in air will be possible, and the forging apparatus will be simpler.To develop such a die material, the authors directed their attention to chromium free nickel-base cast alloys, because such alloys are able to contain a large amount of heavy metals such as molybdenum and tungsten, as being soluble in γ and γ' instead of chromium, and are expected to have higher strength at above 1000°C.Several conventional and experimental alloys were investigated. From the results of compression, compressive creep and oxidation resistance tests, “Nimowal” (Ni-10Mo-12W-6Al-0.01Y) showed the best properties as a whole. Its short-time strength is equivalent to that of Mar-M200 at 950-1000°C, higher than that of Mar-M200 and equivalent to that of TZM at 1050-1100°C. Its compressive creep strength is higher than that of Mar-M200 at 1000-1100°C. Oxidation resistance of Nimowal is equivalent to that of Mar-M200 and enough to be used in air. Moreover, JVimowal has better machinability than Mar-M200.Simulation tests of isothermal forging of superalloys in air were made with Nimowal being used as the die material. One-tenth model disk of In-100 was successfully forged from the extruded billet without any damage or significant oxidation of the die. |
| Databáze: | OpenAIRE |
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