Mechanical Properties Characterization of Heat-Affected Zone Using the Small Punch Test: Use of the small punch test for the mechanical characterization of small areas such as the different zones that characterize the HAZ showed promise

The small punch test (SPT) allows us to make mechanical characterizations of very small regions in any material as it uses very small test specimens (10 x 10 x 0.5 mm 3 ). The SPT can be used to characterize the heat-affected zones (HAZ) of welded joints, the mechanical properties of which are usually unknown, and which are the most problematic areas because of the possible existence of hard and brittle microstructures. Since the SPT can be used to obtain mechanical properties (yield strength, ultimate strength, elongation, fracture energy, and toughness) of small regions, this test was used to evaluate how these properties change inside the HAZ of a welded joint made on a quenched and tempered steel. Several specimens were machined along the HAZ and the corresponding SPTs were performed at room temperature, using a hardness measurement of HV0.5 as a reference. In this case, the strength properties and hardness increase as we move away from the fusion boundary, but the elongation and fracture energy decrease.