Study on surface integrity and fatigue performance of FeCoCrNiAl₀.₆ high-entropy alloy based on thermo-mechanical coordinated control

Abstract

This study investigates the effects of various lubrication techniques on the surface integrity and fatigue life of FeCoCrNiAl0.6 high-entropy alloy during machining. By combining cutting experiments, fatigue tensile tests, and Abaqus/Fe-safe simulations, the research offers a comparative analysis of surface morphology, roughness, and fatigue life across different lubrication scenarios.The findings show a marked improvement in surface quality as cutting speed increases under all lubrication conditions. However, increased cutting depth generally leads to a decline in surface flatness. Specifically, surface roughness decreases with higher cutting speeds. For example, at 1200 m/min in dry cutting, the surface roughness is around 0.77 μm, which drops to 0.40 μm at 3000 m/min, representing a 48 % reduction. Under cryogenic minimum quantity lubrication (CMQL) at 1200 m/min, the roughness is 0.49 μm, decreasing to 0.25 μm at higher speeds, reflecting a 48.9 % reduction.However, increased cutting depth significantly deteriorates surface quality, with a notable rise in surface roughness values. Among the tested lubrication techniques, surface quality ranks as follows: CMQL > MQL > Dry.Regarding fatigue life, higher cutting speeds substantially enhance tensile cycle counts under all lubrication conditions. Specimens under CMQL achieved 2,000,042 cycles, compared to 1,238,520 cycles with minimum quantity lubrication (MQL) and 702,245 cycles in dry cutting—equating to 61.9 % and 35.1 % of the tensile cycle count for CMQL, respectively.Fatigue life decreases with greater cutting depth. For example, compared to a 0.2 mm cutting depth, tensile fatigue cycles decrease by 87.9 % for CMQL, 86 % for MQL, and 91.8 % for dry cutting at a depth of 0.5 mm.