Electrical Discharge Surface Alloying of Superalloy Haynes 230 with Aluminum and Molybdenum

Abstract

Surface alloying of superalloy Haynes 230 was performed using either Al-Mo mixture powders suspended in kerosene or Al-Mo composite electrode during the electrical discharge alloying (EDA). For suspending Al-Mo powders in kerosene, the Cr 23 C 6 , WC 1Àx , and graphite phases exist in the alloyed layer of the EDA specimen with negative electrode polarity, while the specimen with positive electrode polarity exhibits no alloying phase except the raw material phase. For employing the Al-Mo electrode with negative polarity, the specimen represents many discontinuous piled-layers, with Al 3 Mo 8 and AlMo 3 phases accumulating on the substrate surface. The specimen produced using Al-Mo electrode with positive polarity shows an alloyed layer constituted mainly with NiAl phase. This specimen also shows the smallest surface roughness and highest hardness among the four EDA specimens. The kinetics of isothermal oxidation at 1000C in static air demonstrate that the specimen using Al-Mo electrode with positive polarity possesses the best oxidation resistance among the tested specimens.

Machining of Inconel 718 Alloy using EDM-A Review

“…Conversely, the oxidation resistance of the other EDA specimen alloyed with negative electrode polarity was even worse than that of the unalloyed superalloy. In their previous work Bai et al [16] presented the EDA process of the superalloy Haynes 230 with aluminum and molybdenum, and the alloying effects of different EDA conditions have also been determined and compared. Suitable experiment conditions can help to form an aluminum-rich layer on the surface of the superalloy.…”

Influence of grain orientation on the incipient oxidation behavior of Haynes 230 at 900 °C

“…It was demonstrated that inter-granular oxidation and internal oxidation occurred at 982°C and 1093°C after 300 h exposure, respectively. Further, many researcher tried to improve the oxidation behavior of Haynes 230 by several methods, using alloying [22,23], electrical discharge alloying (EDA) [24,25], MOCVD [26] or various surface modification [27,28].…”

Recast layer removal after electrical discharge machining via Taguchi analysis: A feasibility study

“…Average recast thickness is <11 m. Several trim passes show no significant change in workpiece microhardness variation with cracking confined to the recast layer. Bai et al (2004) develop electrical discharge surface alloying of superalloy Haynes 230 with Al and Mo. The produced specimen using the Al-Mo electrode with positive polarity shows an alloyed layer constituted mainly with NiAl phase.…”