Comparison of Flow Stress of Aluminum Alloy 6061-T6 Obtained From Chip Pulling Orthogonal Cutting and Kolsky Bar Testing

Abstract

Machining can be used as a test for the flow stress of materials under conditions of high strain (ε > 1) and strain rate (102/s to 106/s). Constitutive models of metallic materials are conventionally obtained by dynamic compression tests such as the Split-Hopkinson (Kolsky) bar test at lower strain (ε < 0.3) and strain rate (103/s to 104/s). To compare the flow stress obtained from both tests under identical conditions, the strain in the primary shear zone (PSZ) in orthogonal cutting tests has been lowered using high rake angle (α = 45°) cutting tools to ε ≈ 0.8, and by adding chip pulling to ε ≈ 0.5. To our knowledge this is the first time that flow stress estimates are obtained from machining at such low strain values. With some modifications, the strain in Kolsky bar testing has been increased up to ε = 0.8, and the stress-strain curve obtained is compared to flow stress estimates from orthogonal cutting tests under the same strain and similar strain rates. The results work, show for the first time, that the flow stress measured from cutting tests agree closely with those obtained from Kolsky bar testing.