Effect of Vacuum Induction Melting and Vacuum Arc Remelting Treatment on Inclusion Level and Mechanical Properties of AISI H13 Tool Steel

Mechanical Properties of AISI H13 Tool Steel

Abstract

AISI H13 steel grade was produced using vacuum induction melting (VIM) followed by vacuum arc remelting (VAR), instead of the traditional Ingot casting method. Samples were taken from both ingots, namely the conventional and VAR-treated ones. These samples were then forged with the same reduction ratio. The forged samples were tested for non-metallic inclusions. Additionally, gas content analysis was performed using an Oxygen/Nitrogen/Hydrogen detector (OHN-detector) to measure the levels of hydrogen, nitrogen and oxygen in the samples. Mechanical testing was conducted and a comparative analysis was performed to assess how both production routes affected the properties of H13 tool steel. Thermodynamic calculations revealed that the VAR-treated ingots had lower inclusion levels, with a 16% reduction in (Mn, Fe) S, a 25% reduction in sulphides and complete removal of silicates and oxide-based inclusions. These samples also exhibited improved mechanical properties, with a 39.48% increase in impact strength and a 12.11% increase in tensile strength compared to conventionally cast H13. The thermodynamic analysis indicated the presence of MnS and SiO2, along with the trapping of hydrogen and nitrogen. A high non- metallic inclusion index (NMI), combined with hydrogen and nitrogen entrapment, is the primary cause of the reduced mechanical properties.