Charakterisierung von Eisenbasis-Sinterwerkstoffen durch quantitative Fraktographie / Characterization of Pressed and Sintered Ferrous Materials by Quantitative Fractography

Danninger, Herbert; Spoljaric, Davor; Jangg, G.; Weiß, B.; Stickler, R.

doi:10.1515/pm-1994-310202

Cited by 20 publications

(19 citation statements)

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“…Numerous investigations of fracture behaviour of sintered iron and steels under monotonic and especially fatigue loading were reported by many authors, including Danninger et al 16,[28][29][30][31] , Moon, [32][33][34] Slesar and Dudrova et al 13,35,36 and Chawla et al [37][38][39][40] Basic types of fracture facets in sintered iron (Fig. 5a-f and Fig.…”

Section: Fractography Of Sintering Of Iron and Prealloyed Steelsmentioning

confidence: 99%

A review of failure of sintered steels: fractography of static and dynamic crack nucleation, coalescence, growth and propagation

Dudrová

Kabátová

2016

Powder Metallurgy

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The failure of sintered steels differs from the behaviour of wrought steels because of factors such as porosity, remnants of previous particle surfaces and generally more complex microstructures. All these factors influence initiation, growth and propagation of microcracks when the sintered microstructure is mechanically loaded. Fracture paths and fracture resistance are shown to be related to details of the microstructures comprising ferrite, austenite, bainite, martensite, pores and weak interfaces. All these have characteristic fracture resistance properties resulting in, frequently combinations of, dimple rupture, cleavage, intergranular and interparticle failure micromechanisms. Results are presented of systematic studies, enabling identification of relevant stresses, in static and dynamic three-point loading, as the cracking process progresses. In static loading, microcracking has been detected in some steels below the macroscopic yield stress and in the first 100 cycles in fatigue. Microcracks nucleate, grow and coalesce, in a step-wise manner, before achieving a catastrophic sizefor which conventional fracture mechanics holds. Thus, application of Paris-type analysis to Stage II fatigue is therefore inappropriate. The review focuses on failure micromechanisms and interpretation of fracture surface composition of sintered steels, particularly of those based on Distaloy AE and Astaloy CrL powders. The relationships between microstructure and mechanical properties are discussed.

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Section: Fractography Of Sintering Of Iron and Prealloyed Steelsmentioning

confidence: 99%

A review of failure of sintered steels: fractography of static and dynamic crack nucleation, coalescence, growth and propagation

Dudrová

Kabátová

2016

Powder Metallurgy

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“…The sintering of precision parts is usually performed with hardly any shrinkage, which implies that the starting material (the pressed green compact) should have the maximum density already after compaction in order to reach acceptable density valuesand thus mechanical properties. Especially impact energy and elongation to fracture show a strong increase after reaching a density level of about 7.6 g cm −3 , which can be related to closed porosity [11][12][13][14] This means that if the material should be sintered without shrinkage, the compactibility of the powder will determine the final properties, but the compaction pressures that can be applied by technical presses are limited to 600-800 MPa maximum according to technical and economical reasons. Therefore, most of the precision parts are produced within a density range of 6.8-7.1 g cm −3 .…”

Section: Physical Fundamentalsmentioning

confidence: 99%

Section: Physical Fundamentalsmentioning

confidence: 99%

Reactions between ferrous powder compacts and atmospheres during sintering – an overview

Gierl‐Mayer

2020

Powder Metallurgy

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This overview paper describes the interaction of powder metallurgical iron-base alloys with the atmosphere during sintering. The methods of thermal analysis serve to clarify the processes that take place especially during the heating stage of the sintering cycle. After a discussion of the physical and chemical fundamentals of the sintering process, the methods of thermal analysis are explained. The differences between plain iron and alloyed systems are discussed in detail. Classical PM low alloy steels with alloying elements, such as Cu, Ni and Mo, react in a similar way as unalloyed carbon steels. The situation changes dramatically, when oxygen sensitive elements as chromium, manganese and even more silicon come into play. The removal of the surface oxygen is much more crucial, and there are several competing reactions, which have to be considered when these systems should be sintered in industrial scale to reach the desired mechanical and dimensional properties.

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“…A detailed study of the possible effects of these pores on the crack initiation is required for further improving the performance of PM materials. The fracture mechanisms of the sintered iron and steels under loading have been investigated by Danninger et al [4][5][6], Slesar and Dudrová et al [7][8][9] and Chawla et al [9][10][11][12]. For example, Torralba et al used the digital image correlation technique to trace the local deformations in the scanning electron microscopy (SEM) images of the surface of the sintered specimens during tensile tests.…”

Section: Introductionmentioning

confidence: 99%

“…The fracture mechanisms of the sintered iron and steels under loading have been investigated by Danninger et al. [4–6], Slesar and Dudrová et al. [7–9] and Chawla et al.…”

Section: Introductionmentioning

confidence: 99%

Four-dimensional observation of ductile fracture in sintered iron using synchrotron X-ray laminography

et al. 2019

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Synchrotron X-ray laminography was used to examine the time-dependent evolution of the three-dimensional (3D) morphology of micropores in sintered iron during the tensile test. 3D snapshots showed that the networked open pores grow wider than 20 µm along the tensile direction, resulting in the internal necking of the specimen. Subsequently, these pores initiated the cracks perpendicular to the tensile direction by coalescing with the surrounding pre-existing microvoids or with the secondary-generated voids immediately before fracture. Topological analysis of the barycentric positions of these microvoids showed that they form the two-dimensional networks within the ∼20 µm of radius area. These observations strongly indicate that the microvoid coalescence could occur on shear planes formed close to the enlarged open pores or between closed pores by strain accumulation and play an important role in the crack initiation.

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Charakterisierung von Eisenbasis-Sinterwerkstoffen durch quantitative Fraktographie / Characterization of Pressed and Sintered Ferrous Materials by Quantitative Fractography

Cited by 20 publications

References 0 publications

A review of failure of sintered steels: fractography of static and dynamic crack nucleation, coalescence, growth and propagation

A review of failure of sintered steels: fractography of static and dynamic crack nucleation, coalescence, growth and propagation

Reactions between ferrous powder compacts and atmospheres during sintering – an overview

Four-dimensional observation of ductile fracture in sintered iron using synchrotron X-ray laminography

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