A study on die-sinking electrical discharge machining behaviour of friction stir processed AA5052/WS 2 surface composite

Abstract

In the present work, AA5052 alloy is reinforced with 6 vol.% of WS₂ particles through friction stir process. Then, electrical discharge machining process is carried out on AA5052 alloy and friction stir processed AA5052/WS₂ surface composite. The gap voltage, pulse current and pulse on time are selected as input process factors at three different levels. The material removal rate, tool wear rate and surface roughness have opted as output responses and experiments are conducted as per L₂₇ orthogonal array. The electrical discharge machining results of AA5052 alloy revealed that the combined impact of pulse current and pulse on time exists at all gap voltages and affects significantly material removal rate compared to tool wear rate and surface roughness. The electrical discharge machining results of AA5052/WS₂ surface composite revealed that the combined impact of pulse current and pulse on time is similar in material removal rate and surface roughness whereas, in tool wear rate, it is reversed. The TOPSIS technique-based optimal electrical discharge machining process factors for AA5052 alloy is T_on – 60 µs, I_p – 15 amps and V_g – 60 V and for friction stir processed AA5052/WS₂ surface composite is T_on – 60 µs, I_p – 5 amps and V_g 60 V. The scanning electron microscope and energy dispersive X-ray analysis images of electrical discharge machining processed AA5052 alloy and AA5052/WS₂ surface composite revealed the formation of larger and smaller craters, globules, recast layers, micro pits and cracks.