Dry sliding wear and mechanical behaviour of selective laser melting processed 18Ni300 and H13 steels for moulds

In today's manufacturing, selective laser melting (SLM) enables the production of 3D metal parts with innovative designs. However, this technique is still limited to certain materials due to residual stresses and cracking. The ultra-low carbon maraging steel 18Ni300 is a proven steel for SLM processing, while H13 steel still presents some challenges due to cracking and low wettability. These two steels are currently used in mould making due to their mechanical properties. Aiming to compare and better understand the behaviour of these two steels manufactured by selective laser melting, their mechanical performance and dry sliding wear were investigated. Both steels processed by SLM exhibited the expected yield stress and tensile strength values, suitable for mould making. Dry sliding wear tests performed using a pin-on-disc apparatus, where pins of steel were pressed against discs of polypropylene reinforced with 40 wt% short E-glass fibres, showed that the H13 steel had a specific wear rate two orders of magnitude lower than the 18Ni300 steel (0.11 x 10-7 mm3/m.N). The wear mechanism of the 18Ni300 steel is abrasion, while fatigue plays the main role in the H13 steel. The results of this work allow to establish a correlation between the obtained microstructure, mechanical behaviour and tribological performance of both steels under the tested conditions and show that the H13 steel, processed by SLM, can be a good choice for the critical zones of moulds where a higher wear resistance is required.