Microstructural and mechanical aspects of laser metal deposited H13 powder for die repair

Abstract

In this study, the microstructural and mechanical properties of H13 powder deposited via laser metal deposition (LMD) on H13 hot work tool steel substrates were examined. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD) were used to analyze the grain distribution, layer development, and carbide incidence. The mechanical properties were evaluated using Vickers hardness indentations. An α-ferrite matrix consisting of α’-martensite was identified along with a crack-free interface containing Mo- and Cr-rich precipitates between the additive-deposited H13 steel and the substrate. The EBSD results showed a highly consistent combination between the deposition and the substrate, along with a structure consisting of columnar and equiaxial grains resulting from the directional solidification process. Wear resistance tests demonstrated that the H13-deposited region was in a better condition than the substrate was due to the presence of martensite and carbides in the matrix. Finally, the average hardness levels of the substrate and deposition regions were determined to be 213 HV (α-Fe) and 671 HV (α’), respectively. The smooth transition in terms of hardness between the regions also indicated a tendency for lower stress concentrations.