Journal ArticleDOI
Surface analysis of PM martensitic steel before and after consolidation Part 1: Surface analysis of powder
Lars Nyborg,I. Olefjord +1 more
TLDR
In this article, the surface analysis of Fe12Cr martensitic steel powder was performed using electron spectroscopy for chemical analysis and Auger electron spectrographs for surface analysis and showed that the composition and thickness of the surface oxides are independent of powder particle size.Abstract:
Surface analysis of Fe12Cr martensitic steel powder was performed using electron spectroscopy for chemical analysis and Auger electron spectroscopy. The analysed powder was produced by nitrogen gas atomisation, the average particle size being 190 μm. In the as atomised condition the powder is covered by particles of manganese, chromium, and iron oxides, as well as a thin (3 nm) layer mainly consisting of Fe2O3. The average thickness of the oxide particles is ~13 nm, whereas the total average oxide thickness is ~7 nm. The composition and thickness of the surface oxides are independent of powder particle size in spite of the difference in cooling rate between large and small metal particles. The liquid metal droplets solidify at or below 1400°C. Most of the oxide is formed during solidification. It is suggested that a mixed oxide (MnCr2O4) is produced. Above 1400°C no metallic oxide is formed due to the oxidation of carbon to carbon monoxide. At very high temperatures manganese evaporates. During c...read more
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Characterization of surface oxides on water-atomized steel powder by XPS/AES depth profiling and nano-scale lateral surface analysis
TL;DR: In this article, the surface properties of steel powders were investigated using X-ray photoelectron spectroscopy, Auger electron spectroscope, and high resolution scanning electron microscopy combined with Xray microanalysis, which revealed that the powder is covered by a homogeneous (similar to 6 nm thick) Fe-oxide layer to similar to 94%.
Journal ArticleDOI
Effect of atomization on surface oxide composition in 316L stainless steel powders for additive manufacturing
Dmitri Riabov,Dmitri Riabov,Eduard Hryha,Masoud Rashidi,Masoud Rashidi,Sven Bengtsson,Lars Nyborg +6 more
TL;DR: In this article, the surface oxides consisted of a thin (~4 nm) iron oxide (Fe2O3) layer with particulate oxide phases rich in Cr, Mn, and Si.
Journal ArticleDOI
Surface studies of powder metallurgical stainless steel
TL;DR: In this paper, the reaction products formed on the surfaces of gas-atomized 12Cr steel powder are determined using ESCA and AES, and it is shown that Cr and Mn oxide particles larger than about 10 nm are formed at high temperatures during atomization.
Journal ArticleDOI
Controlling factors determining flowability of powders for additive manufacturing: A combined experimental and simulation study
Yufan Zhao,Yujie Cui,Yusaku Hasebe,Huakang Bian,Kenta Yamanaka,Kenta Aoyagi,Takehito Hagisawa,Akihiko Chiba +7 more
TL;DR: In this paper, Inconel 718 alloy powders were prepared by gas atomization, plasma atomization (PA), and plasma rotating electrode process (PREP), and the flowability was experimentally evaluated by the avalanche angle.
Microstructure and properties of modern P/M super duplex stainless steels
TL;DR: In this article, a large research program on modern industrial duplex stainless steels has been carried out at the Laboratory of Engineering Materials, Helsinki University of Technology for about a decade, and extended collection of data was obtained on the microstructure, precipitation properties, mechanical and corrosion properties of Duplok 27, a novel grade of super-duplex stainless steel designed and manufactured by Metso Oyj by power metallurgy (P/M) technology by hot isostatic pressing (HIP).
References
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Journal ArticleDOI
Surface Analysis of Gas Atomized Ferritic Steel Powder
I. Olefjord,Lars Nyborg +1 more
TL;DR: The surface of gas atomized ferritic powder, Fe-25Cr, was studied by ESCA and Auger spectro-scopy as discussed by the authors, and it was found that 60% of the total amount of oxygen is bound in the surface oxide.