High Strength Sintered Steels Containing Chromium and Manganese

Tengzelius, J.; Blände, C.A.; Wastenson, G.

doi:10.4271/810242

Cited by 5 publications

(4 citation statements)

References 2 publications

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“…there is not so much difference between prealloyed and mixed grades in that respect. Furthermore, the risk of oxygen pickup during sintering – which has been reported to be critical [17] – should not be overestimated. Cr forms passivating layers, and even if some oxygen is picked up by the Cr particles, either from the atmosphere or from the base iron powder through the ‘internal getter effect’ [18–20], high-temperature sintering will result in quite efficient reduction.…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution during sintering of Fe-Cr-C steels prepared from admixed elemental powders

2023

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In the upcoming years, a reduction in the use of critical elements, such as Ni and Cu, with unstable prices and high demand from the electromobility sector will become increasingly important for the PM-industry. Cr-alloyed sintered steels offer attractive properties at a moderate cost, but so far mostly Cr-prealloyed grades have been used. This work analyses the microstructural homogenisation process when Cr is introduced as admixed elemental powder. It is shown howdue to its high carbon affinity -Cr particles act as 'internal carbon-getters'. There is an intermediate 'heterogenization' of the microstructure, i.e. the iron matrix is decarburised due to the formation of (Cr, Fe)-carbides. Final homogenisation depends on the formation of a transient liquid phase through the eutectic reaction between carbides and the iron matrix. Thus, the microstructure is not only sensitive to aspects such as sintering temperature or Cr-particle size but also to the heating rate and small variations in nominal carbon.

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Section: Introductionmentioning

confidence: 99%

Microstructural evolution during sintering of Fe-Cr-C steels prepared from admixed elemental powders

2023

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“…The use of Ni is further restricted by its classification as carcinogenic, which virtually prevents the use of free Ni powder, and Cu in steels offers recycling problems. Therefore, especially Cr- and Mn-alloyed steels have received increased attention by the PM community quite early [6–12], while commercial exploitation started from about 2000, with the introduction of water-atomised pre-alloyed powders [13–15].…”

Section: Introductionmentioning

confidence: 99%

Chemical reactions during sintering of PM steel compacts as a function of the alloying route

2018

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Due to their large specific surface, powders and powder compacts typically contain significant amounts of oxygen which has to be removed in the early stages of sintering. In the present study, it is shown that the homogeneity/heterogeneity of the oxygen affinity within the compact, which depends on the alloying route chosen, strongly affects the de-oxidation process. For several types of alloy steels, it is shown that systems alloyed through the mixing or master alloy route and containing elements with widely varying oxygen affinity exhibit oxygen transfer reactions through the internal gas phase. For pre-alloyed grades, in which the oxygen affinity is homogeneous, i.e. consistent between the powder particles, transfer reactions occur rather within the metallic particles themselves. In any case, the sintering temperature should be selected such as to grant reduction also of the most stable oxides contained.

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“…Some of them are designed to eliminate porosity, such as powder forging for the whole part or rolling techniques for surface densification which strengthen the gear teeth wherever the rest of the part stays porous. The second approach is to introduce alloying elements as Cr, Mn, Si or V [3][4][5] which are the main work horses for ingot metallurgy to produce heat treatable steels. These alloying elements have very positive impact on the hardenability of steels, and their second advantage is that they are much cheaper than the conventional alloying elements used in PM.…”

Section: Introductionmentioning

confidence: 99%

Dilatometry Coupled with Mass Spectrometry as Instrument for Process Control in Sintering of Powder Metallurgy Steels

Gierl‐Mayer

Danninger

2016

MSF

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The production of ferrous powder metallurgical parts by the press-and-sinter route becomes more and more attractive. Today, parts are produced for loading requirements that until now only could be fulfilled by conventional produced steel components. The high mechanical properties that must be attained require the use of alloying elements so far not common in powder metallurgy because of their high affinity for oxygen. The sintering of chromium containing steels is a challenge for the whole production process, because the reduction of the surface oxides is critical for successful sintering.Dilatometry can be a useful instrument to control the sintering behaviour of the materials, especially the combination with mass spectrometry allows analysing the very complex sintering process and simultaneously monitoring the solid-gas reactions. This work shows that the sintering atmosphere plays a major role in the entire process. Degassing and deoxidation processes during sintering are demonstrated for different alloying systems (Fe, Fe-C, Fe-Mo-C, Fe-Cr-Mo-C). Dilatometry coupled with MS is shown to be a very good instrument for process control of the sintering process. The generated analytical data can be related to the mechanical properties of the sintered steels if the size of the specimen is large enough.

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High Strength Sintered Steels Containing Chromium and Manganese

Cited by 5 publications

References 2 publications

Microstructural evolution during sintering of Fe-Cr-C steels prepared from admixed elemental powders

Microstructural evolution during sintering of Fe-Cr-C steels prepared from admixed elemental powders

Chemical reactions during sintering of PM steel compacts as a function of the alloying route

Dilatometry Coupled with Mass Spectrometry as Instrument for Process Control in Sintering of Powder Metallurgy Steels

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