Tailoring chip morphology by correlating the microstructure and dynamic yield strength in turning of lead-free silicon brasses

摘要

In this work, we reported a framework to quantitatively evaluate and tailor chip breaking capability by correlating the microstructure and dynamic yield strength in cuffing of alpha + beta silicon brasses. The microstructure of the silicon brasses was controlled by designing the elements compositions and resultant alpha and beta contents by zinc equivalent rule. Increasing beta content leaded monotonously to the increase in the quasi-static tensile yield strength. In contrast, the dynamic yield strength (sigma(d)) determined by J.G. William's cutting model had a sudden drop regime for the alpha + beta silicon brasses with the increased zinc equivalent. Exactly, the easy chip breaking capability was achieved for the alpha +beta silicon brasses with the sudden-drop sigma(d), which was associated to the dominant thermal-softening behavior compared with the strain hardening one during the chip formation process for the brasses with the predominant alpha phase. Specifically, we proposed the methodology that adopts the sigma(d) as an index to evaluate and tailor the easy chip breaking capability of the alpha +beta silicon brasses. This work substantiated the methodology of correlating the microstructure control via the composition design and the sigma(d) determined from the chip geometric parameters could be utilized to evaluate and tailor chip breaking capability of metallic materials.