Selective laser melting of P20 mould steel: investigation on the resultant microstructure, high-temperature hardness and corrosion resistance

ABSTRACT

Additive manufacturing (AM) & 3D printing can realise rapid delivery of high-quality and complex-geometry industrial product like steel mould with conformal cooling channels. In this paper, selective laser melting (SLM), a typical AM technique, was used to investigate the processing of P20 tool steel which is commonly used for plastic mould. SLM processing parameters, including scanning speed and laser power, were investigated to produce test specimens with high density. High cooling rate induced formation of refined dendrite and major crystalline phases in the as-printed P20 are identified largely as martensite, with an additional small portion of retained austenite. A subsequent tempering heat treatment has been done to eliminate these metastable phases and guarantee overall structural stability and mechanical property of the as-printed P20. Hardness at 250°C and corrosion resistance in 3.5 wt-% NaCl aqueous solutions were measured to evaluate the reliability of P20 mould steel under service, which show rather satisfactory results.

KEYWORDS:

• Selective laser melting
• additive manufacturing
• P20
• steel
• corrosion

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

H. X. Li is a research assistant in Southern University of Science and Technology of China now and she will commence her phd study in 2018. Her Master Degree (July 2015) and Bachorlar Degree (July 2012) were obtained from the Northeastern Petroleum University of China. Her research is focused on additive manufactureing of steels.

H. L. Qi is a senior student in Southern University of Science and Technology of China. She will receive her Bachorlar Degree in July 2018. She is currently working on additive manufactureing of steels.

Dr. C. H. Song is a school lecturer in the South China University of Technology now. He received his doctoral education & training from the South China University of Technology (2009–2014) and Peking University (2014–2016). He has been published 32 SCI/EI papers in total and areas of research in which he is interested is “laser material manufacturing”.

Dr. Y. L. Li had his education at the Harbin Institute of Technology during September 1997 to October 2006, and pursued his B.S., M.S., and Ph.D. from the State Key Lab of Advanced Welding Production Technology during the period July 2001 to October 2006. The areas of research in which he is interested are “Optical smart metal structure”, “Brazing mechanism and processing”, and “New material joining and 3D printing”.

Dr M. Yan received his doctoral education & training from Harbin Institute of Technology & The University of Queensland (UQ). He was an ARC Australian Postdoctoral Fellow (2009–2012) and then Queensland Smart Future Fellow (2012–2014) associated with UQ. He joined SUSTC in the December of 2014 as an associate professor. He has published 75 internationally peer reviewed papers with leading journals in his field, and won research grant totaling worth of ∼$2 million. He will take the Humboldt Fellowship For Experienced Researchers from year 2018 to learn from top German scientists in the field of 3d printing & additive manufacturing.

Additional information

Funding

The study is financially supported by the Peacock Program of the Shenzhen Government and Shenzhen Science and Technology Innovation Commission under Peacock Program Project No. 20150518260C.