Advanced powder metallurgy steel alloys

Danninger, Herbert; Gierl‐Mayer, Christian

doi:10.1533/9780857098900.2.149

Cited by 26 publications

(22 citation statements)

References 15 publications

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“…[3] MnCr 2 O 4 spinels were not only observed in sintered specimens prepared with high Mn-alloyed steel powder but also after the heat treatment of Fe-1.5Cr-0.2Mo or Fe-1.8Cr powders with trace amounts of manganese in their compositions. [4,6,21,24,25] Similar particles were also found but rarely spread in the 450-H material (see spots 1 and 2 in Figure 2b). A second population of particles is characterized by high concentrations of Mn, Si, and O.…”

Section: Conventional Characterization Using Sem-edssupporting

confidence: 54%

“…However, the actual atmospheric conditions inside bulk specimens are critical aspects during sintering of bulk PM materials, whereas oxide particles entrapped during consolidation cannot be eliminated anymore. [6,25] The particle size (depicted as area) of the oxide particles classified for chemistry is given in Figure 9. The comparison of an area-equivalent diameter or the aspect ratio of the particles would be misleading, because the particle shape largely differs between circular-and irregular-shaped (see Figure 2 The average size of all non-metallic inclusions is widely independent from the debinding temperature in case of subsequent consolidation in hydrogen atmosphere but significantly designated when flushing argon is used.…”

Section: Microstructural Characterization Using Afamentioning

confidence: 99%

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Investigations on Oxide Particles Formed during Sintering of CrMnNi‐Transformation‐Induced Plasticity (TRIP) Steel Powder Metallurgically Materials Using Automatic Feature Analysis

et al. 2020

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The combination of powder metallurgical and ceramics-derived processing enables the manufacturing of innovative metal components. Using high-alloyed transformation-induced plasticity (TRIP) steels facilitates the manufacturing of metal components with outstanding mechanical properties for advanced load applications. The oxygen affinity of some alloying elements promotes the formation of non-metallic particles during sintering, which deteriorate the mechanical properties. Bulk specimens are prepared from a 17Cr7Mn6Ni-TRIP steel powder using a ceramics-derived extrusion process with organic binders at ambient temperature. Processing comprises the thermal binder removal in air and the sintering in pure argon or hydrogen atmospheres. The sintered specimens are analyzed for their amount and composition of non-metallic particles using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The focus of this article is on the automated particle identification and analysis using an automatic SEM-EDS-related device. The automatic feature analysis provides statistical information on the chemistry, size, and morphology. The particles mainly consist of Cr, Mn, Si, and O forming Mn 2 SiO 4 and MnCr 2 O 4. The number of particles mainly depends on the debinding temperature and on the sintering atmosphere. The use of a pure hydrogen sintering atmosphere significantly depresses the formation of MnCr 2 O 4 , whereas silicates remain stable under the applied atmospheric and thermal conditions.

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Section: Conventional Characterization Using Sem-edssupporting

confidence: 54%

Section: Microstructural Characterization Using Afamentioning

confidence: 99%

Investigations on Oxide Particles Formed during Sintering of CrMnNi‐Transformation‐Induced Plasticity (TRIP) Steel Powder Metallurgically Materials Using Automatic Feature Analysis

et al. 2020

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“…The relative density of the powder metal material will also influence several mechanical properties. The dynamic Young's modulus, hardness, and tensile strength of powder metal steel are shown to have a roughly linear relation to the relative density (7,8).…”

Section: Introductionmentioning

confidence: 95%

Influence of the DIN 3962 Quality Class on the Efficiency in Honed Powder Metal and Wrought Steel Gears

Bergstedt

Holmberg

Lindholm

et al. 2020

Tribology Transactions

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To increase the efficiency of a gearbox, research on gear mesh loss is of importance. Britton et al. concluded that the surface finishing method affects the gear mesh efficiency. The efficiency benefits of superfinishing a surface and reducing the surface roughness have been reported by Kahraman. A novel method for calculating the bearing loss torque was proposed by Tu et al. Andersson et al. found that the efficiency can vary between 2 and 5% during repeated efficiency tests due to variations in the assembly process. This work investigates how the honing surface finishing process and DIN 3962 quality class affect the gear mesh efficiency by performing tests in an FZG back-to-back test rig. Two materials, a powder metal and a wrought steel, were tested. All gears were finished using a honing process and sorted according the measured quality class. Powder metal gears of class 6, 7, 8, and !9 and wrought steel gears of class 6, 7, and !9 were tested. The efficiency were calculated from measuring the torque required to maintain a constant velocity of the FZG test rig. The results from the efficiency tests showed no significant difference in efficiency between the wrought steel and powder metal steel gears. In addition, no obvious correlation between the DIN 3962 quality class and the gear mesh efficiency could be found. When examining the wrought steel material it was found that the reproducibility of the efficiency was comparable to the assembly error of the test rig, despite the variation in quality class.

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“…In parallel, the ductile matrix is easily deformed, whereby large and flat interparticle contacts are commonly observed [33]. The compaction also means that the oxide layer must be accommodated in the deformed microstructure, something that likely promotes crack formation, deformation [34] and spalling of the oxide layer, re-oxidation of the exposed metal surfaces and even presence of cold welding between metal particles [4,35]. Furthermore, the porosity of the compact is decreased compared to loose powder.…”

Section: Compacted Samplesmentioning

confidence: 99%

Oxide reduction and oxygen removal in water-atomized iron powder: a kinetic study

Wendel

Manchili

Hryha

et al. 2020

J Therm Anal Calorim

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Reduction of oxides during sintering is a prerequisite for the manufacturing of powder metallurgy steels. Inadequate control of the sintering atmosphere may impede sinter neck formation and cause entrapment and growth of oxides in sinter necks, ultimately deteriorating the mechanical properties of sintered components. In this study, the oxide reduction and oxygen removal in water-atomized iron powder was investigated by means of thermogravimetric analysis in pure hydrogen. Two principal mass loss events were recorded, corresponding to the removal of the surface oxide layer at around 400 °C and reduction of internal and stable oxides in the range 600–1350 °C. The apparent activation energies of these mass loss processes were determined by means of kinetic analyses, giving values around 100 kJ mol−1 and 200–400 kJ mol−1, respectively. The validity of the results was asserted using hematite reference samples which displayed good correlation with the reduction of the surface oxide layer, thereby showing that the powder surfaces are covered by an Fe2O3 oxide. The high-temperature mass loss, with no analogy in the reference samples, is believed to originate from a combination of oxygen removal from internal oxides and stable oxide particulates on the surface. Analysis of the oxide reduction in iron powder compacts show a slightly lower activation energy for the oxide layer reduction, indicating an influence of the compaction step on the initial state of the powder and oxide layer. At the same time, the high-temperature mass loss event was shifted to higher temperatures, which is believed to be caused by the increasingly restricted mass transport of reduction products along the pores in the sintered compact.

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Advanced powder metallurgy steel alloys

Cited by 26 publications

References 15 publications

Investigations on Oxide Particles Formed during Sintering of CrMnNi‐Transformation‐Induced Plasticity (TRIP) Steel Powder Metallurgically Materials Using Automatic Feature Analysis

Investigations on Oxide Particles Formed during Sintering of CrMnNi‐Transformation‐Induced Plasticity (TRIP) Steel Powder Metallurgically Materials Using Automatic Feature Analysis

Influence of the DIN 3962 Quality Class on the Efficiency in Honed Powder Metal and Wrought Steel Gears

Oxide reduction and oxygen removal in water-atomized iron powder: a kinetic study

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