The Effect of Bulk Residual Stress on Milling-Induced Residual Stress and Distortion

Abstract Background Distortion arises during machining of metallic parts from two main mechanisms: 1) release bulk residual stress (BRS) in the pre-form, and 2) permanent deformation induced by cut tools. Interaction between these mechanisms is unexplored. Objective Assess this interaction using aluminum samples that have a flat surface with variations BRS, where subsequently milled, we observe milling-induced (MIRS) distortion. Methods Plate are kinds large blocks, one kind stress-relieved stretching second solution heat treated, quenched aged. The BRS field plates known recent series measurements, being small relieved (within ±20 MPa) (±100 plates, varying tension to compression over milled. MIRS measured following milling hole-drilling. Distortions thin wafers at milled surfaces used elucidate BRS/MIRS interactions. A finite element (FE) model strength materials each assess consistency wafer distortion MIRS. Results Milling high magnitude changes directions relative direction, direction maximum curvature rotating toward or away depending on sign BRS. High was also found increase peak arc height, nearly doubling amount low samples. Conclusion Measured observed both show interactions Stress analysis models differences consistent