Microstructure, solidification texture, and thermal stability of 316 L stainless steel manufactured by laser powder bed fusion
Review article, 2018

This article overviews the scientific results of the microstructural features observed in 316 L stainless steel manufactured by the laser powder bed fusion (LPBF) method obtained by the authors, and discusses the results with respect to the recently published literature. Microscopic features of the LPBF microstructure, i.e., epitaxial nucleation, cellular structure, microsegregation, porosity, competitive colony growth, and solidification texture, were experimentally studied by scanning and transmission electron microscopy, diffraction methods, and atom probe tomography. The influence of laser power and laser scanning speed on the microstructure was discussed in the perspective of governing the microstructure by controlling the process parameters. It was shown that the three-dimensional (3D) zig-zag solidification texture observed in the LPBF 316 L was related to the laser scanning strategy. The thermal stability of the microstructure was investigated under isothermal annealing conditions. It was shown that the cells formed at solidification started to disappear at about 800 °C, and that this process leads to a substantial decrease in hardness. Colony boundaries, nevertheless, were quite stable, and no significant grain growth was observed after heat treatment at 1050 °C. The observed experimental results are discussed with respect to the fundamental knowledge of the solidification processes, and compared with the existing literature data.

Electron microscopy

Solidification texture

Laser powder bed fusion

Thermal stability of microstructure

Cellular solidification

316 L stainless steel

Author

Pavel Krakhmalev

Karlstad University

Gunnel Fredriksson

Karlstad University

Krister Svensson

Karlstad University

Igor Yadroitsev

Central University of Technology, Free State

Ina Yadroitsava

Central University of Technology, Free State

Mattias Thuvander

Chalmers, Physics, Materials Microstructure

Ru Peng

Linköping University

Metals

2075-4701 (eISSN)

Vol. 8 8 643

Subject Categories

Ceramics

Manufacturing, Surface and Joining Technology

Metallurgy and Metallic Materials

DOI

10.3390/met8080643

More information

Latest update

9/18/2018