Undesired distortion can arise during machining of metals from two main mechanisms: 1) release of bulk residual stress in the pre-form, and 2) deformation induced by the cutting tool. The interaction between these two mechanisms is explored herein using aluminum plate-shaped samples that have a large surface with variations of bulk residual stress (BRS), where that surface is subsequently milled and we observe milling-induced residual stress (MIRS) and distortion. Plate samples are cut from two kinds of large blocks, one kind stress-relieved by stretching and a second kind that had been solution heat treated, quenched, and aged. MIRS is measured following milling using hole-drilling with fine depth increments. Distortions of thin wafers cut at the milled surfaces are used to show how the interactions between BRS and MIRS change milling-induced distortion. Data from the study show that the directions of MIRS and distortion relative to the milling direction are changed when milling in samples with high BRS magnitude (roughly ±100 MPa), with the direction of maximum curvature rotating toward or away from the milling direction depending on the sign and direction of BRS. High magnitude BRS increased distortion, nearly doubling the amount found compared to milling in samples free of BRS.

The high-strength aluminum alloy V92Zr, part of the Al-Zn-Mg system, is a self-quenched alloy. Its primary alloying elements include 4.2 wt% Mg, 3.2 wt% Zn, 0.6 wt% Mn, and 0.15 wt% Zr. The most suitable filler wires for welding this alloy are V92W, AMg6, AMg4Zr, and No.11 (Al-Zn-Mg). This alloy is applicable in aircraft production. Prolonged heating at 50-70°C can lead to significant structural changes in the precipitation hardening of aluminum alloys due to the transition from zone aging to phase aging. Studies indicate that zone aging of Al-Zn-Mg alloys, particularly in weld seams, with repeated heating at 50-70°C, substantially increases strength while reducing elongation, cross-sectional area reduction, toughness, stress corrosion resistance, and increasing susceptibility to cracking. Research has shown that even heating at temperatures below the phase aging threshold can significantly alter the properties. This article examines the effects of prolonged low-temperature heating on the mechanical properties, crack sensitivity in impact bending, and corrosion resistance of semi-finished products and weldments of V92Zr aluminum alloys after solution treatment and aging at room and elevated temperatures.