The wrought- and cast-alloy BÖHLER L334 VMR (Alloy 718; DIN-Nr.: 2.4668) is a precipitation-hardening Ni-base alloy (Ni-Cr-Fe). The main properties are the high hot strength and hot yield strength up to 750°C, the good creep behaviour up to 700°C, the corrosion resistance and the weldability. The alloy is used for the production of gas turbines, aerospace engines, nuclear reactors, pumps and hot work applications like tools for extrusion and forging die inserts. The alloy BÖHLER L334 VMR is produced by remelting in a vacuum arc furnace. The solidification structure has an important influence on the mechanical properties. By means of practical measurements and computer simulation the influence of different melting rates and currents on the solidification structure should be described. The secondary dendrite spacings and the size of primary carbides have to be measured to determine the local solidification time. By constructing the pool profiles by hand, the shape (v- or u-shaped), the pool depth and consequently the solidification structure can be described. This is important for understanding the direction of the heat flow, the temperature gradient and the appearance of different flow patterns during the process. By comparing the measurements with the computer simulation, a good agreement of the results can be found in principle.
|Translated title of the contribution
|Analysis of the cast structure and the conditions of solidification of the Ni-base Alloy 718 remelted in a vacuum arc furnace
|7 Apr 2006
|Published - 2006
Bibliographical noteembargoed until null
- Ni-base alloy vacuum arc furnace solidification structure poolprofiles secondary dendrite spacings primary carbides pool depth