Investigation on H13 buildups produced with wire arc additive manufacturing: Deposition strategies-induced microstructural evolution and mechanical performances

Highlights: • Four H13 blocky buildups, with different deposition strategies, were produced by robotic CMT technology. • A bimodal microstructure was tailored, for all deposition parts, in overlap zone and body zone, respectively. • Relatively enhanced mechanical properties were acquired for the ones with the same scanning strategies. • Wear surface hardness evolved as a result of locally martensitic evolution, rather than deposition strategy. • Relationship of "deposition strategy - microstructural evolution - mechanical performance" was established. -- Abstract: In this work, H13 buildups were produced through wire-arc additive manufacturing based on cold metal transfer technology. Four different deposition strategies were employed for the fabrication and the microstructural evolution and mechanical properties of the corresponding buildups were compared. A bimodal microstructure for all buildups produced in the overlap zone (OZ) and body zone (BZ), respectively, despite a mixture of lath-shaped martensites and blocky δ-ferrites in the OZ and a slightly coarser but still fine martensites in the BZ. The as-deposited mechanical properties were evidently superior to the properties of the base metal after annealing, but slightly inferior to that after quenching and tempering. Compared with the components with different deposition patterns between adjacent layers, the relatively enhanced hardness and wear-resistance properties were acquired for the ones with the same scanning strategies, being responsible for the smaller retained δ-ferrite size in the OZ and slightly refined martensites in the BZ. The deposition strategy had a negligible influence on the wear surface hardness, all decreasing gradually from the wear zone to the transient zone and finally keeping stable as a result of the locally martensitic evolution. As the in-situ thermal history was influenced by the deposition strategies, both of the microstructural distribution and mechanical performances were affected by the deposition strategies. Besides, the applied strategies, characterized by the different scanning directions between adjacent tracks, had a negligible influence on microstructures and mechanical properties following comparison with the counterparts with the different directions between adjacent layers.