Effects of powder recycling on stainless steel powder and built material properties in metal powder bed fusion processes

Published

February 27, 2017

Author(s)

Gregor Jacob, Christopher U. Brown, M A. Donmez, Stephanie S. Watson

Abstract

A series of 11 identical laser based powder bed fusion (PBF) builds were completed with varying amounts of virgin and recycled nitrogen gas atomized S17-4 PH stainless steel powder following a specific powder recycling strategy that simulates industrial practice. Mechanical properties of parts were evaluated using tensile and hardness tests. Recycled powder properties, such as particle size distribution, flowability, chemical composition, and microstructure were evaluated. The recycled powder showed no significant changes in its particle size and particle shape but apparent density and powder bed density increased while flow time improved. Recycling the powder in a nitrogen atmosphere caused a slight increase of the martensite phase in the predominately austenitic S17-4 PH powder. PBF fabricated austenitic-/ martensitic S17-4 PH showed a ratio of approximately 50 % to 50 % between austenite and martensite. Tensile tests on the stress relieve heat treated specimens did not show any dramatic change in the tensile properties with recycling up to 11 times. The fine dendritic, austenitic / martensitic microstructure of the stress relieved heat treated S17-4 PH reached a tensile strength of YS0.2 above 520 MPa, and an elongation of 28 %. Mechanical and material properties from specimens fabricated from powder recycled up to 11 times were similar to specimens fabricated from virgin powder.

Citation

Advanced Manufacturing Series (NIST AMS) - 100-6

Report Number

100-6

NIST Pub Series

Advanced Manufacturing Series (NIST AMS)

Pub Type

NIST Pubs

Download Paper

https://doi.org/10.6028/NIST.AMS.100-6

Keywords

Precipitation Hardening Stainless Steel, Powder Bed Fusion, Martensite, Austenite, Powder Properties, Mechanical Material Properties, Surface Roughness, Recycling, Multiply Use, and Powder Management.

Citation

Jacob, G. , Brown, C. , Donmez, M. and Watson, S. (2017), Effects of powder recycling on stainless steel powder and built material properties in metal powder bed fusion processes, Advanced Manufacturing Series (NIST AMS), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.AMS.100-6 (Accessed October 5, 2024)