Friction Stir Welding to Join Wrought Homogenized Armor Steel

W. Evans, R.A.R. Giorjão, M. Eff, M. McDonnell, A.J. Ramirez
The Ohio State University, United States

Keywords: Armor Steel, Friction Stir Welding, Hardness, Mechanical Properties

The United State Army employs several advanced armored combat vehicles, in a wide array of different environments, and applications. Armor steels are required to meet certain conditions to stay within the military’s specifications. Vehicle armor is typically joined using arc welding methods. Joining via arc welding degrades armor material below specification, so alternate joining methods are being explored like FSW. FSW is a solid-state joining technique that utilizes non-consumable tool to stir two materials into a joint. The benefit to using FSW is an increase in joint efficiency and a decrease in joint defects. In this study FSW parameters were developed and used to weld Wrought Homogeneous Armor steel (roughly 400 HV). The welded joints were subjected to both destructive and non-destructive examination for quality assessment. Metallography, micro hardness indention, and thermal modeling was also employed to predict the joint’s properties. Through this work parameters were down-selected to make a defect free weld, and the FSW SZ exhibited a tempered martensitic microstructure matching that of the base metal. Properties of the SZ are then expected to be quite similar to that of the unaffected wrought armor steel.