The ITk detector, the new ATLAS silicon tracking system for the High Luminosity LHC (HL-LHC), will be equipped with 3D pixel sensor modules in the innermost layer (L0). The pixel cell dimensions will be 25x100 μm$^2$ in the barrel and 50x50 μm$^2$ in the end-caps, with one readout electrode at the centre of each pixel and four bias electrodes at the corners. Sensors from pre-production wafers (50x50 μm$^2$) produced by FBK have been bump-bonded to ITkPixV1.1 chips at IZM. Bare modules have been assembled in Genoa on Single Chip Cards (SCCs) and characterized in laboratory measurements and in test beam campaigns. Some of these modules have been irradiated in Bonn and at the CERN IRRAD facility. Preliminary results of their characterization after irradiation are shown, including measurements performed during test beam campaigns at CERN SPS in Summer 2022.