The impact of peening on residual stress in wire-arc additive manufactured Ti-6Al-4V using contour method and phased array ultrasonics

Additive Manufacturing (AM) is increasingly used to produce complex components, with Wire Arc Additive Manufacturing (WAAM) playing a crucial role in industries such as aerospace, particularly for titanium alloys like Ti-6Al-4V.
However, WAAM introduces significant Residual Stress (RS) due to the high heat input, which can lead to component failure. Therefore, understanding how to evaluate RS in Ti-6Al-4V WAAM-manufactured components and minimizing its effects is essential.

Peening can mitigate tensile RS by introducing compressive stress, making it important to assess its impact on WAAM samples. In this study, RS measurements were conducted using both the newly developed Phased Array Ultrasonics for Residual Stress Measurement (PAURS) and the well-established Contour Method.

While various RS measurement techniques exist, there is a gap in understanding how PAURS can be effectively applied. To address this, The Contour Method was used to validate PAURS results on WAAM Ti-6Al-4V samples. RS was evaluated in both peened and unpeened samples, enabling a comparative analysis.

Results showed that (I) PAURS and The Contour Method exhibited good qualitative agreement in as-built samples, and (II) peening effectively introduced up to 800 MPa compressive stress on the top surface of WAAM components.