Characterization of Eurofer-97 TIG-welded joints by FIMEC indentation tests

Welded joints of 25-mm thick plates of Eurofer-97, produced by a multi-pass GTAW + filler material method, have been investigated before and after different heat treatments to identify the temperature–time combination that gives mechanical properties as close as possible to those of the base material. After NDE (non-destructive examinations), samples were annealed in the temperature range 730–750 °C for 1 and 2 h, microhardness was measured across the joints and FIMEC (flat-top cylinder indenter for mechanical characterization) tests were carried out in the molten zone (MZ), heat affected zone (HAZ) and in the matrix. The FIMEC method allowed determination on a local scale of the yield stress as obtained in standard tensile tests. Mechanical tests were supplemented by optical microscopy observations. The best results were obtained by the treatment at 750 °C for 2 h: original characteristics are substantially recovered in the HAZ but not completely in the MZ.