Effect of process parameters on microstructures and properties of DZ125 superalloy solidified by LMC

Abstract

High thermal gradient in the interface region of melting and solidified metal during the unidirectional solidification has significant impact on the microstructures and mechanical properties of the castings. In this paper, DZ125 superalloy was solidified by directional equipment associated with liquid metal cooling medium of Ga-In alloy. Several process parameters have been chosen in order to understand the effect of thermal gradient on the castings. Comparing with traditional high rate solidification prepared DZ125 superalloy, the results show that element segregation such as Al, Ti, W and Mo was decreased with high thermal gradients or high withdraw rates, the precipitation of low melting phase in the interdendritic region was suppressed and the sizes of eutectic and c9 phase were both refined. Stress-rupture test was carried out at 980uC/235 MPa after heat treatment. Obvious stress-rupture improvement has been observed, and the stress-rupture life decrease at high withdrawal rate due to the column grain discontinuity and deflection.

Effect of Zr on solidification and microstructure of a Ni-based superalloy with high Al and Ti contents

“…Studies have shown that during solidification of Ni-based superalloys, the formation of coarse eutectic (γ+γ′) can be inhibited by raising cooling rates [15][16][17] . However, this method is only applicable to small cross-section ingots [18] . Minor elements C, B and Zr are usually doped in Ni-based wrought superalloys for better mechanical properties [19][20][21][22] .…”

Effect of heat input on cracking in laser solid formed DZ4125 superalloy

“…However, for the nickel-based superalloys with high Al and Ti content (generally Al þTi4 6 wt%), the hot cracking can be easily formed during high energy beam processing [7]. The typical instances include DZ4125 [8], Rene80 [9], Inconel 738LC [10], Inconel 713C [11] and AllVac718PLUS [12]. Previous study has shown that Inconel 738LC superalloy, which contained the considerable amount of Al and Ti (Al þTi 46 wt%), is susceptible to the cracking in the heat affected zone (HAZ) during LSF [13].…”