Analyzing the Influence of Simultaneously Austenitization and Multi-Directional Boriding on the Surface and Subsurface of H13 Tool Steel

AISI H13 hot tool steel is very much famous for elevated temperature operations such as manufacturing of dies, molds, glass, and plastics. In order to extend the lifespan, surface hardening treatments such as nitriding, carburizing and boriding are as famous as austenitizing followed by dual tempering for overall core-structure enhancement. In this study, boriding (at 960 °C for 3 h) is combined with the conventionally used heat-treatments for the surface enhancement of H13 dies and substrates. Feasibility analysis, detailed surface and subsurface characterization, SEM, EDX and WDX analyses on the formed Fe₂B and CrB rich coatings are performed. Results showed that faster cooling rates at the die openings, shrinkage of the middle sections of die and thermal mismatches between the hard layers and host material caused the formation of cracks parallel and perpendicular to the die orifices. Formation of ferrite pits, which were characterized with lower hardness, was witnessed in the vicinity of hard layers. This was attributed to accumulation of Si under the boride layers.