Title: Effect of niobium on microstructure-property relationship in H11 hot-work tool steel via wire- and powder-based laser metal deposition

Authors: Mahesh Teli; Fritz Klocke; Kristian Arntz; Kai Winands

Addresses: Fraunhofer Institute for Production Technology, IPT, D-52074 Aachen, Germany ' Fraunhofer Institute for Production Technology, IPT, D-52074 Aachen, Germany; Laboratory for Machine Tools and Production Engineering (WZL), RWTH Aachen University, D-52074 Aachen, Germany ' Fraunhofer Institute for Production Technology, IPT, D-52074 Aachen, Germany ' Fraunhofer Institute for Production Technology, IPT, D-52074 Aachen, Germany

Abstract: This paper presents an effect of niobium (Nb) on the microstructure-property relationship in H11 hot-work tool steel. Various amounts of Nb powder were introduced into the molten pool of H11 wire through a novel wire- and powder-based laser metal deposition (WP-LMD) process. With the increase in Nb content up to 3.45 wt.%, the average grain size of H11 decreased from 14.3 µm to 2.83 µm, while the average Vickers microhardness decreased from 706 HV_0.2 to 301 HV_0.2. The critical amount of Nb was then found to be 1.73 wt.%, which produced a hard (average hardness of 606 HV_0.2), and refined (average grain size of 3.01 µm) microstructure of H11. Such kind of microstructures can assure high toughness and high hardness; hence more suitable for hot-working industries such as die and mould, forging and cutting tools.

Keywords: laser metal deposition; AISI H11 wire; niobium powder; microstructure refinement; toughness; hardness.

DOI: 10.1504/IJMMS.2018.092870

International Journal of Mechatronics and Manufacturing Systems, 2018 Vol.11 No.2/3, pp.135 - 147

Received: 02 Sep 2017
Accepted: 28 Nov 2017
Published online: 01 Jul 2018 *

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