Additive Manufacturing of Particle Reinforced Stainless Steel Composites
Pörhönen, Antti (2016)
2016
Materiaalitekniikan koulutusohjelma
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2016-06-08
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201605204026
https://urn.fi/URN:NBN:fi:tty-201605204026
Tiivistelmä
In this work, manufacturing of silicon carbide (SiC) particle reinforced stainless steel matrix composites by direct metal laser sintering (DMLS) has been investigated. DMLS is a relatively new additive manufacturing method in which powdered raw material is melted by a scanning laser beam to form a solid work piece one layer at a time. The matrix material used in the study has been EOS StainlessSteel 316L, which is an austenitic high chromium stainless steel grade. The SiC particles were added to the base metal powder in three different concentrations and mixed by simple mechanical mixing. The rate of mixture homogeneity was studied by means of chemical analysis and field emission scanning electron microscopic (FE-SEM) analysis. The solid part manufacturing was performed with EOS M100 DMLS system using standard EOS StainlessSteel 316L process parameter set. Mechanical properties of the composite materials were tested by tensile-, impact-, wear- and hardness testing, and their resistance to corrosion was analyzed by salt water immersion and electrochemical testing. Also structural characterization was performed to the samples by means of optical microscopy, density measurements, FE-SEM + EDS analysis and X-ray diffraction (XRD) analysis.
It was observed that tensile strength and wear resistance of the 316L steel could be significantly increased by the SiC particle addition, while ductility and impact toughness properties of the composites were greatly reduced. Also moderate increase of hardness was observed. The SiC particle concentration in the composites had a nearly linear effect on these properties, with a sharp reduction of ductility and impact toughness in the case of the highest SiC concentration samples. The effect of SiC particle addition on corrosion resistance of the materials was seen to be mostly insignificant, although partly contradictory results were obtained. The obtained results can be considered promising, as the measured improvements of mechanical properties were superior to the results documented in most previous studies regarding similarly reinforced composite materials. This has been partly attributed to the characteristic properties of the DMLS process, which differ notably from the ones of conventional powder metallurgical manufacturing methods, such as solid-state sintering.
It was observed that tensile strength and wear resistance of the 316L steel could be significantly increased by the SiC particle addition, while ductility and impact toughness properties of the composites were greatly reduced. Also moderate increase of hardness was observed. The SiC particle concentration in the composites had a nearly linear effect on these properties, with a sharp reduction of ductility and impact toughness in the case of the highest SiC concentration samples. The effect of SiC particle addition on corrosion resistance of the materials was seen to be mostly insignificant, although partly contradictory results were obtained. The obtained results can be considered promising, as the measured improvements of mechanical properties were superior to the results documented in most previous studies regarding similarly reinforced composite materials. This has been partly attributed to the characteristic properties of the DMLS process, which differ notably from the ones of conventional powder metallurgical manufacturing methods, such as solid-state sintering.