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Abstract

G-X 40 NiCrNb 35 25 (also known as Manaurite 36X or HP40Nb) is a centrifugal casting alloy mainly used in the petrochemical industry at temperatures ranging between 950 C and 1100 C. Precipitation-hardened alloys are particularly prone to changes in their characteristics under these conditions, due to a coarsening of the precipitates. It is observed that storage enhances the properties of the material. The possibility of using thermal pre-treatment to improve creep behaviour has been investigated. 40mm x 8mm samples of the material were subjected to various temperature time treatments. One batch was kept at 1000 C for 8000h. Samples in a second batch were kept at 1050 C 3h, 1050 C 65h and 1100 C 65h. Their behaviour under creep-inducing stress at 1000 C was subsequently observed. Results showed that storage and thermal pre-ageing improve the creep characteristics of the material, mainly due to an increase in ductility. Since storage leads to coarser carbides, which occupy grain boundaries to a considerable extent, increased ductility was an unexpected result. With the help of electron microscope data it was, however, possible to put forward a likely explanation.

Additional information

Authors: GUTTMAN V, JRC PETTEN ESTAB. (NL);SCHOENHERR H JRC PETTEN ESTAB. (NL), JRC PETTEN ESTAB. (NL)
Bibliographic Reference: PAPER PRESENTED: ZWOELFTE VORTRAGSVERANSTALTUNG, DUESSELDORF (DE), DECEMBER 1, 1989 AVAILABLE FROM COMMISSION OF THE EUROPEAN COMMUNITIES, DG XIII-C-3, L-2920 LUXEMBOURG AS PAPER DE 35144 ORA
Availability: Can be ordered online
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