Process for the production of hard metal bodies

A two-stage process combining controlled laser-based additive manufacturing and sintering produces hard metal bodies with high density and stable microstructure, addressing defects in existing methods and ensuring mechanical stability.

DE102018102616B4Active Publication Date: 2026-05-13FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
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Patent Information

Application Number
DE102018102616
Authority / Receiving Office
DE · DE
Patent Type
Patents
Current Assignee / Owner
Filing Date
2018-02-06
Publication Date
2026-05-13
Estimated Expiration
2038-02-06

AI Technical Summary

Technical Problem

Existing laser-based additive manufacturing processes for hard metal bodies suffer from insufficient densification, leading to microstructural defects such as free carbon, pure tungsten, tungsten dicarbide, and various η-phases, which deteriorate the mechanical properties, and high temperatures cause WC decomposition and cobalt evaporation.

Method used

A two-stage process involving laser-based additive manufacturing with controlled energy input followed by vacuum or gas pressure sintering to produce hard metal bodies with a density of ≥ 98%, featuring a microstructure of WC particles in a cobalt-rich matrix without undesirable phases, using laser powers of 20 W to 55 W, scan speeds of 20 mm/s to 75 mm/s, and subsequent sintering at up to 1600°C.

Benefits of technology

The method achieves hard metal bodies with high density and stable microstructure, free from defects like W2C, W, and η-phases, maintaining mechanical integrity and preventing cobalt loss, resulting in hard metal components suitable for wear parts and tools.

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Abstract

Method for producing hard metal bodies that have a hard metal microstructure at room temperature, which is free of tungsten dicarbide and eta phase, in which LPBF, SLM, DMLS or SLS as a laser-based additive manufacturing process with energy input via laser powers of 20 W to 55 W and scan speeds of 20 mm / s to 75 mm / s and track spacings of 30 µm to 205 µm and layer thicknesses of 20 µm to 45 µm at each point of energy input to achieve a temperature of 800 °C to a maximum of < 1800 °C from hard metal granules as starting materials made of WC as a ceramic hard material with Co as a metallic binder phase and an additive of Cr3C2 and the hard metal granules have a porosity of > 0 vol.% to 40 vol.%.-%, a hard metal green body with a density of at least 50% and at most 70% of the theoretical density of the hard metal body is produced, and which is subsequently subjected to sintering at temperatures up to a maximum of 1600 °C, by means of vacuum sintering at temperatures of 1200 to 1600 °C and at partial pressures of 100 to 90000 Pa or gas pressure sintering at temperatures of 1380 to 1600 °C and pressures of 5 to 10 MPa until a density of the hard metal body of ≥ 98% to 99.9% of the theoretical density.
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