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

Abstract

In this work, we reported a framework to quantitatively evaluate and tailor chip breaking capability by correlating the microstructure and dynamic yield strength in cutting of α+β silicon brasses. The microstructure of the silicon brasses was controlled by designing the elements compositions and resultant α and β contents by zinc equivalent rule. Increasing β content leaded monotonously to the increase in the quasi-static tensile yield strength. In contrast, the dynamic yield strength (σd) determined by J.G. William’s cutting model had a sudden drop regime for the α+β silicon brasses with the increased zinc equivalent. Exactly, the easy chip breaking capability was achieved for the α+β silicon brasses with the sudden-drop σd, 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 α phase. Specifically, we proposed the methodology that adopts the σd as an index to evaluate and tailor the easy chip breaking capability of the α+β silicon brasses. This work substantiated the methodology of correlating the microstructure control via the composition design and the σd determined from the chip geometric parameters could be utilized to evaluate and tailor chip breaking capability of metallic materials.