Effect of scanning speed on formability of 718HH mould steel produced by selective laser melting

doi:10.13251/j.issn.0254-6051.2023.04.025

Abstract

Abstract: 718HH plastic mould steel parts were prepared by selective laser melting in the laser scanning speed range of 800-1100 mm/s, and the influence of laser scanning speed on forming quality, microstructure and microhardness of the 718HH plastic mould steel specimens produced by selective laser melting was studied by optical microscopy, scanning electron microscopy and semi-automatic microhardness tester. The results show that with the increase of the scanning speed, the number and size of holes inside the formed parts increase, and cracks of different degrees appear on the side surface boundary. The microstructure of the formed parts is mainly composed of martensite as revealed by metallographic etching, the typical molten pool morphology can be observed on the side surface, and the distribution of the molten pool becomes more and more uneven with the increase of the scanning speed. The formed parts have higher microhardness, and due to the comprehensive influence of grain size, residual stress, hole cracks and other defects, the average microhardness of molded parts shows a trend of increasing first and then decreasing with the increase of the scanning speed. When the scanning speed is 800 mm/s, there are almost no defects such as holes and cracks inside the part, the formed microstructure is dense and has a good microhardness value, so it is suitable for the selective laser melting of the 718HH plastic mould steel.

Key words: selective laser melting, 718HH plastic mould steel, scanning speed, forming quality, microstructure, microhardness

CLC Number:

TG142.1

Zhang Mengxing, Ma Dangshen, Zhou Jian, Chi Hongxiao, Wang Changjun. Effect of scanning speed on formability of 718HH mould steel produced by selective laser melting[J]. Heat Treatment of Metals, 2023, 48(4): 155-160.

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