Surface composition of the steel powders pre-alloyed with manganese

Hryha, Eduard; Gierl, Christian; Nyborg, Lars; Danninger, Herbert; Dudrová, E.

doi:10.1016/j.apsusc.2010.01.055

Cited by 110 publications

(123 citation statements)

References 19 publications

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“…Moreover, in high temperatures, above 1000°C, the dominant mechanism for the reduction of oxides and the activation of the sintering process is the carbothermal reaction. This effect has been described in another works [15][16][17]. Based on all of the obtained results, it may be observed that using an inert atmosphere with 10 % H 2 is enough to obtain the same results as after sintering in a reducing atmosphere of hydrogen.…”

Section: Resultssupporting

confidence: 70%

Dilatometric study of low-alloy steels with silicon carbide addition

Hebda

Dębecka

Kazior

2016

J Therm Anal Calorim

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Low-alloy steels produced via the traditional powder metallurgy process, using a die compaction, are currently widely used. Therefore, improving their properties is an issue that attracts much attention. The most common method of enhancing the properties of a given material is introducing additives, e.g., silicon to prealloyed low-alloy steels. It may be added through the mechanical alloying process. The article presents the results of research focused on an analysis of the influence of: (1) the mechanical alloying process, (2) various amounts of silicon carbide: 1, 2 or 3 mass% and carbon addition: 0.4 or 0.6 mass%, (3) different atmospheres, reducing or inert with 10 mass% of hydrogen and (4) the effect of annealing on phenomena occurring during the sintering of low-alloy steel. Moreover, changes in the sinters' microstructure and microhardness were also investigated. Based on the results, it was found that an increase in the amount of silicon in the material causes an increase in the shrinkage of the samples, prepared using mechanical alloying, during the sintering process. This observed effect was independent of the carbon content (0.4 or 0.6 mass%) in the samples as well as of the sintering atmosphere (reducing or inert with 10 mass% of hydrogen). The smallest porosity was observed for samples sintered directly after the mechanical alloying process. There is no need to use a hydrogen atmosphere during sintering-10 % of hydrogen added to an inert, e.g., helium atmosphere is enough to sinter the samples correctly.

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Section: Resultssupporting

confidence: 70%

Dilatometric study of low-alloy steels with silicon carbide addition

Hebda

Dębecka

Kazior

2016

J Therm Anal Calorim

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“…5a for mixes containing water-atomized metallic Fe with 0.5 mass/% graphite. The surface of different Fe-based atomized powders has been characterized in several studies by Nyborg et al using surface sensitive analysis techniques [18][19][20][21]. Water-atomized powders are typically covered by a homogeneous iron oxide layer formed by Fe 2 O 3 with a thickness of around 6-8 nm and disperse particulate oxides of a higher stability (mainly Cr-, Mn-and Si-containing oxides) with an average size of 200 nm [22].…”

Section: °Cmentioning

confidence: 99%

Application of thermal analysis techniques to study the oxidation/reduction phenomena during sintering of steels containing oxygen-sensitive alloying elements

Calderon

Gierl‐Mayer

Danninger

2016

J Therm Anal Calorim

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For the consolidation of steel parts manufactured by powder metallurgy (PM) techniques, removal of the surface oxides covering metallic powder particles is a necessary prerequisite. In PM steels with conventional compositions, reduction of the oxides is easily achieved in traditional sintering furnaces. However, processing steels containing alloying elements with a high oxygen affinity represents a big challenge that requires a deeper understanding of the chemical processes occurring during sintering. In the present work, thermogravimetry analysis coupled with mass spectrometry is used to describe the oxidation/reduction phenomena that take place when sintering steel powders and how these processes are modified by the addition of admixed particles containing oxygensensitive elements. Carbothermal reduction processes are studied using pure oxides (Fe 2 O 3 , MnO 2 , Cr 2 O 3 and SiO 2 ) as well as water-atomized Fe powders mixed with small amounts-4 mass/%-of Cr, Mn and Si powders or FeMn-Si-(Cr) master alloy powders. The results show that there is an oxygen transfer from the base iron particles to the oxidation-sensitive elements-''internal getter effect''-taking place mostly through the gas phase. Different alloying elements (Cr, Mn, Si) show different temperature ranges of susceptibility to oxidation. Combination of these oxygen-sensitive alloying elements in the form of a master alloy powder reduces their sensitivity to oxidation. Also, the use of master alloys promotes the concentration of the oxides on the surface of the alloying particles and not in the grain boundaries of the surrounding iron particlesas occurs when using Mn carriers-which should have a beneficial impact on the final mechanical performance.

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“…Currently, the available references on the sublimation/evaporation behaviour of Mn-containing Fe-based alloys mainly focuses on alloys with low Mn content (≤5 wt. %) [28][29][30]. We recently reported on the sublimation behaviour of Fe-28Mn-3Si alloys [31] at different sintering temperatures ranging from 1000 • C to 1200 • C. For the first time, we calculated the sublimation rate of the sintered samples as a function of sintering temperature and discussed the factors that affect the sublimation of the Fe-Mn samples.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sintering Time on the Densification, Microstructure, Weight Loss and Tensile Properties of a Powder Metallurgical Fe-Mn-Si Alloy

Hodgson

Chang

et al. 2017

Metals

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This work investigated the isothermal holding time dependence of the densification, microstructure, weight loss, and tensile properties of Fe-Mn-Si powder compacts. Elemental Fe, Mn, and Si powder mixtures with a nominal composition of Fe-28Mn-3Si (in weight percent) were ball milled for 5 h and subsequently pressed under a uniaxial pressure of 400 MPa. The compacted Fe-Mn-Si powder mixtures were sintered at 1200 • C for 0, 1, 2, and 3 h, respectively. In general, the density, weight loss, and tensile properties increased with the increase of the isothermal holding time. A significant increase in density, weight loss, and tensile properties occurred in the compacts being isothermally held for 1 h, as compared to those with no isothermal holding. However, further extension of the isothermal holding time (2 and 3 h) only played a limited role in promoting the sintered density and tensile properties. The weight loss of the sintered compacts was mainly caused by the sublimation of Mn in the Mn depletion region on the surface layer of the sintered Fe-Mn-Si compacts. The length of the Mn depletion region increased with the isothermal holding time. A single α-Fe phase was detected on the surface of all of the sintered compacts, and the locations beyond the Mn depletion region were comprised of a dual dominant γ-austenite and minor ε-martensite.

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Surface composition of the steel powders pre-alloyed with manganese

Cited by 110 publications

References 19 publications

Dilatometric study of low-alloy steels with silicon carbide addition

Dilatometric study of low-alloy steels with silicon carbide addition

Application of thermal analysis techniques to study the oxidation/reduction phenomena during sintering of steels containing oxygen-sensitive alloying elements

Effect of Sintering Time on the Densification, Microstructure, Weight Loss and Tensile Properties of a Powder Metallurgical Fe-Mn-Si Alloy

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