Barkhausen Noise monitoring of microstructure and surface residual stress in maraging steel manufactured by Powder Bed Fusion and aging

Laser Powder Bed Fusion (LPBF) refers to processes conducted layerwise from material powder, which delivers innovative shapes. Nondestructive inspection can significantly benefit LPBF products, considering the tight application requirements. Magnetic Barkhausen Noise (MBN) is an interesting method due to its potential for nondestructive in situ inspections; however, it is still a concern for additively manufactured parts because of their complex microstructure. This study investigated how the MBN signal is influenced by the maraging steel microstructure and surface residual stress in LPBF parts with two build orientations (XYZ and YZX) before and after aging (480 degrees C for 3 h). Microstructural characterizations were performed with multiple microscopy techniques. Surface residual stress was assessed with X-ray diffraction, and the MBN was collected along two directions (theta 0 degrees and theta 90 degrees). Different correlation coefficients between surface residual stress and MBNenergy, varying between 0.53 (theta 0 degrees) and 0.98 (theta 90 degrees), could be mainly explained by surface stress states and some microstructural differences, like the columnar structures and weak crystallographic texture along build orientation. MBN envelope shapes also allow the comprehension of surface residual stress changes undistinguished with the MBNenergy. These findings clarified some potential uses of the MBN for inspecting Laser Powder Bed Fused materials.