| Electric hot machining (EHM) can effectively improve machining properties of difficult machining materials. It's an easily operating processing technology of low production cost which makes lower environment pollution. NAK80 die steel and GH4169 nickel-base superalloy are two kinds of typical difficult machining materials which are widely used. NAK80 die steel's high hardness leads to higher costs as it needs to be cutted by high-speed steel or superhard alloy tools. GH4169 nickel-base superalloy is one of the most difficult machining materials. There is a lot of plastic deformation during cutting on the surface of GH4169 nickel-base superalloy which leads to great cold hardeningThis paper aims to explore the feasibility of using EHM on NAK80 die steel and GH4169 nickel-base superalloy. At the same time, the surface integrity, which includes surface roughness, work hardening and residual stress, has been researched.The influence of machining parameters on surface roughness has been researched. The test shows that with the increase of each factor, surface roughness decreases first and then increases. In addition, when machining NAK80 by EHM, the order of machining parameters' influence magnitude is cutting speed, cutting depth, current. But when machining GH4169 by EHM, the rank is cutting depth, current and cutting speed.In this paper, orthogonal tests of EHM on two materials have been designed and carried out. The results show that surface of NAK80 die steel with Ra 0.4093 ?m can be achieved by EHM, as well as surface of GH4169 nickel-base superalloy with Ra 0.34229 ?m.Work hardening and residual stress of typical difficult machining materials' surfaces created by EHM have been measured. The measurement shows that there is almost no work hardening on the surface of NAK80 created by EHM, the work hardening on the surface of GH4169 is obviously decreased compared with ordinary cutting, while the residual stress is increased... |
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