Chromium Alloy for Dies
Development of Cr Base Alloy as an Efficient Tool Material for Forging with Operation Temperature up to 1250 oC in Air
Tech Area / Field
- MAT-ALL/High Performance Metals and Alloys/Materials
- CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
3 Approved without Funding
AO Kompozit, Russia, Moscow reg., Korolev
- VNIIKhT (Chemical Technology), Russia, Moscow
- Midland Metals International Inc., Canada, ON, Toronto\nAubert & Duval, France, Paris Cedex 15
Project summaryThe project is devoted to development of Cr base alloy for dies capable to efficiently work at temperature up to 1250 0C in air at isothermal deformation forging of gas-pump parts from superalloys for increase of its durability.
Today the isothermal forging dies are make from nickel base superalloys JS6U (Russia) or “Nimoval” Ni-10Mo-8W-6Al (Japan). These alloys work up to temperatures
1000 0C and 1200 0C respectively. For superalloys, where the working temperature is up to 1200-1250 °C, mentioned alloys can’t be used because of their low cyclic creep resistance at temperatures higher than 1100 0C and low heat resistance in these conditions of the second alloy. For dies working at temperatures higher than 1200 0C molybdenum is used. But in this case an expensive vacuum isothermal deformation block is necessary to exclude penetrating oxidation of molybdenum at heating. Development of high heat-resistant and high temperature strength chrome-based alloy will allow manufacturing items blanks from heat-resistant alloys by isothermal forging in air atmosphere without vacuum equipment. In this project we plan to lead theoretical optimization of composition on the base of system Cr-Fe-W-Ti-Hf-Zr.
The solution of the problem is possible only if hot isostatic pressing (HIP) will be used. This technology allows manufacturing dies with complex die impression that finally will allow producing items of complicated shape from heat-resistant alloys. At the same time it should be pay attention to the development of technology of experimental bars made of heat-resistant chrome alloys melting using method of vacuum-induction melting with further HIP.
The most wide-spread methodology of die material efficiency is estimation of cyclic creep resistance level and heat-resistance of the alloy from which the die is made. That’s why the purpose of this work is the development chrome-based alloy composition, which will have increased cyclic creep resistance at compression and oxidation at heating up to 1250 0C.
For manufacturing chrome base alloys bars the technology of vacuum-induction melting was chosen. This technology complies most of all with standards on metal quality, demanded from heat-resistant chrome alloys.
The advantages of vacuum-induction melting are the following:
- deep metal degassing, flotation and removal of non-metallic inclusions due to long duration of molten metal and its mixing;
- removal of volatile components admixtures due to high temperature, low pressure and long duration of molten metal in the furnace;
- manufacturing of bars from complex compositions alloys with use the almost any kind of raw materials;
- high productivity
- complex molding manufacturing possibility.
Vacuum-induction melting has its disadvantages:
- the contact of molten metal in vacuum with fire-resistant crucible fettling that reduces refining effect of melting;
- low crucibles durability;
- complexity of installations.
For the new high heat-resistant chrome-based die alloy technological process of manufacturing from it half-finished products by HIP casting consolidation only lies ahead in the context of realization of working plan of present Project ISTC. That’s why the purpose of the present Project is the development and optimization of composition of chrome-based alloy for dies efficient up to 1250 оC for isothermal deformation in air atmosphere of heat-resistant alloys, used in equipment for gas-pumping to increase its service life.
The prospective result of this work is the development of composition and technologies of manufacturing of die blanks with complex die impression from chrome-based alloy. Finally it will allow producing items of complicated shape from heat-resistant alloys.
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