Microstructure and mechanical properties of laser solid formed 30Cr–Mn–Si–Ni–2A ultra-high-strength steel

ABSTRACT

Microstructure and mechanical properties of laser solid formed 30Cr–Mn–Si–Ni–2A steel are investigated. The deposits consist of epitaxial columnar grains, equiaxed grains or direction changed dendrites can be observed in the bulk specimens. The microstructure at the bottom of deposits is mainly composed of tempered martensite; the middle to top zone of the deposits are characterised by martensite and bainite. With the increasing of deposition height, the volume fraction of bainite increases, the size of martensite laths increases but its volume fraction decreases. The microhardness shows a decrease from the bottom zone to the middle–upper zone, and then a significant increase at the top of the deposits. Anisotropic and unevenly distributed tensile properties are observed for the deposits. Samples after heat treatment demonstrate tensile strength of 1720 MPa and elongation rate of 8.7%.

KEYWORDS:

• 30Cr–Mn–Si–Ni–2A
• ultra-high-strength steel
• laser solid forming
• additive manufacturing
• microstructure
• mechanical properties

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

M. Wang http://orcid.org/0000-0002-0978-0272

Q. Wang http://orcid.org/0000-0003-4490-7889

X. Lin http://orcid.org/0000-0002-7491-8928

W. D. Huang http://orcid.org/0000-0002-1139-854X

Additional information

Funding

This research was supported by National Key R&D Program of China (Grant No. 2016YFB1101003), National Defence Basic Scientific Research Program of China (Grant No. JCKY2017204A021), and Ningxia Thirteen Five-Years Major Science and Technology Project (Grant Nos. 2018BCE01001 and 2016BZ08).