Selective Laser Melting of TiB2-Reinforced S136 Die Steels

HU Hui1 ZHOU Yan2 WEN Shifeng1 WEI Qingsong

(1.State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China 430074)
(2.Faculty of Engineering, China University of Geosciences, Wuhan, Hubei, China 430074)

【Abstract】The selective laser melting (SLM) technology is used to process the TiB2/S136 composites and the effect of laser energy density η on the densities, microstructures and mechanical properties of SLM-processed specimens is investigated. X-ray diffraction instrument, field emission scanning electron microscopy and transmission electron microscopy are used to study the phase compositions, surface morphologies and microstructures of specimens. The results show that when η is low, the powders are not fully molten and thus a large amount of residual pores are formed. However, when η is too high, the micro-cracks are formed in the specimens because of thermal stress. When η is 66.7 J/mm3, the specimens have less surface defects, and their densities are up to 97.3%. There exist fine and uniformly-distributed equiaxed grains. As for these specimens, the average microhardness is up to 742.4 HV0.1, and the average friction coefficient and wear rate are 0.559 3 and 0.272 × 10−4mm3·N−1·m−1, respectively, indicating an excellent abrasion resistance performance. The tensile strength is 1 051.3 MPa and the elongation is 5.84%, indicating a relatively good plasticity. Above all, the optimal η for the SLM-processed TiB2/S136 composites is 66.7 J/mm3, and if η is too high or too low, the densities and mechanical properties of TiB2/S136 composites would be seriously affected. This study provides a useful theoretical basis and process guidance for SLM-processed high-performance die steels.

【Keywords】 laser optics; selective laser melting; energy density; TiB2/S136 composites; microstructure; mechanical properties;

【DOI】

【Funds】 National High-tech R&D Program of China (863 Program) (2015AA042501)

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(Translated by LIU T)

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This Article

ISSN:0258-7025

CN: 31-1339/TN

Vol 45, No. 12, Pages 131-140

December 2018

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Article Outline

Abstract

  • 1 Introduction
  • 2 Test method
  • 3 Test results and analysis
  • 4 Conclusions
  • References