Plasticity criteria for porous metals

Laptev, Alexander M.

doi:10.1007/bf00802566

Cited by 7 publications

(5 citation statements)

References 2 publications

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“…These models are a modification of the classical von Mises theory of plasticity. [89,90] The Skorokhod-Olevsky and Abouaf models consider the volume change by two independent functions of porosity. The main difference between the Skorokhod-Olevsky and Abouaf approaches is in the determination of porosity functions.…”

Section: Basicsmentioning

confidence: 99%

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

Laptev,

Bram,

Garbiec

et al. 2024

Adv Eng Mater

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Spark plasma sintering as the prominent field‐assisted sintering technique (FAST/SPS) is a novel technology for the rapid, pressure‐assisted consolidation of powder materials. The main feature of FAST/SPS is the Joule heating of the used tooling. Tooling is a core part of the FAST/SPS setup, which must withstand high pressure at elevated temperatures ensuring a uniform temperature distribution inside the sintered part. This review looks at the standard FAST/SPS tooling, the specific tooling used for sintering complex‐shaped parts and for pressureless sintering. A particular focus lies on the graphite, the commonly used tooling material, and on alternative materials such as steel, alloys, ceramics, and composites. The review also considers the add‐on tooling elements, including spacers, foils, and thermal insulation. Furthermore, the paper discusses the basics of FAST/SPS modeling, the computer‐based optimization of FAST/SPS tooling, the simulation procedure used, and the modelling accuracy. The review briefly describes the tooling and equipment for manufacturing upsized parts and large‐scale production. In addition, the paper considers the tooling for FAST/SPS sintering under high pressure (up to 1 GPa) and ultra‐high pressure (over 1 GPa). The paper concludes with an analysis of the challenges and prospective solutions for the continued development of FAST/SPS tooling.This article is protected by copyright. All rights reserved.

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Section: Basicsmentioning

confidence: 99%

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

Laptev,

Bram,

Garbiec

et al. 2024

Adv Eng Mater

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“…There is also an approach that considers a powder sample as a quasi-continuous two-phase body that can decrease in volume under the effect of pressure. In this case, the compaction of the quasi-continuous body in a rigid die makes it possible to obtain the corresponding equations for describing PCP [20][21][22][23][24][25]. This approach can be considered a continuous one.…”

Section: Introductionmentioning

confidence: 99%

“…Constants and coefficient of determination R 2 obtained via approximation of experimental data on the compaction of powders of iron, copper, nickel, and FeKH3, FeKH6 and FeKH9 using Equation(21).…”

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confidence: 99%

New Die-Compaction Equations for Powders as a Result of Known Equations Correction: Part 1–Review and Analysis of Various Die-Compaction Equations

Laptiev

2024

Powders

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The well-known equations for the powder compaction process (PCP) in a rigid die published from the beginning of the last century until today were considered in this review. Most of the considered equations are converted into the dependences of densification pressure on the powder’s relative density. The equations were analyzed and their ability to describe PCP was assessed by defining the coefficient of determination when approximating experimental data on the compaction of various powders. It was shown that most of the equations contain two constants the values of which are determined by fitting the mathematical dependence to the experimental curve. Such equations are able to describe PCP with high accuracy for the compaction of powders up to a relative density of 0.9–0.95. It was also shown that different equations can describe PCP in the density range from the initial density to 0.9 with the same high accuracy, but when the process of compaction is extrapolated to higher values of density, the curves diverge. This indicates the importance of equations that can unambiguously describe PCP to a relative density equal to or close to 1.0. For an adequate description of PCP for relative density greater than 0.95, equations containing three or four constants have proven useful.

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“…Although these studies were based on the theory of plasticity for porous bodies, using the rheological properties of porous bodies necessitated a refinement of the results obtained. Therefore, this paper analyzes the strain hardening of the matrix in a porous body using the theory of plasticity and new data on the rheological properties of porous bodies.The modern theory of plasticity for porous and powder bodies is based on the continuum approach adopted by continuum mechanics [5][6][7][8][9][10]. A porous body to be compacted is a two-phase isotropic composite in which powder…”

mentioning

confidence: 99%

“…The modern theory of plasticity for porous and powder bodies is based on the continuum approach adopted by continuum mechanics [5][6][7][8][9][10]. A porous body to be compacted is a two-phase isotropic composite in which powder…”

mentioning

confidence: 99%

Strain hardening of a powder body in pressing

Koval'chenko

2009

Powder Metall Met Ceram

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The compaction of powders in a press mold is analyzed using the theory of plasticity for porous and powder bodies and a rheological model that includes elastic, viscous, and plastically hardenable elements of the matrix forming a porous deformable body. In cold-pressing conditions, plasticity is the main factor influencing the behavior of the porous body under external pressure. The shear yield stress of the matrix versus its mean-square-root strain is calculated. It is shown that the dependence of the mean relative density of a compactable body on the applied pressure is determined by the variation in the shear yield stress of the matrix due to strain hardening for metal bodies and due to the brittle fracture of particles along with strain hardening during compaction for non-metal powders. An analysis of data on powder compaction under continuous pressure increase by calculating the above dependences shows features of matrix strain hardening and their effect on powder compaction in a press mold.The qualitative description of powder compaction under external pressure distinguishes four overlapping stages: repacking of powder particles and an increase in the coordination number; irreversible deformation localized where particles are in contact; homogenous deformation of the powder body; and bulk compression [1]. The increase in the coordination number of randomly packed particles is also observed at subsequent stages. The coordination number of closely packed identical (in size) particles may reach 14, while that of orderly packed identical particles is no more than 12, which is typical of the closest packing in crystals. Irreversible plastic deformation, which changes the shape of particles, leads to strain hardening that degrades the compactability of the powder body. Strain hardening is of current importance for powder metallurgy. It has been studied in many papers [1][2][3][4]. Although these studies were based on the theory of plasticity for porous bodies, using the rheological properties of porous bodies necessitated a refinement of the results obtained. Therefore, this paper analyzes the strain hardening of the matrix in a porous body using the theory of plasticity and new data on the rheological properties of porous bodies.The modern theory of plasticity for porous and powder bodies is based on the continuum approach adopted by continuum mechanics [5][6][7][8][9][10]. A porous body to be compacted is a two-phase isotropic composite in which powder

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Plasticity criteria for porous metals

Cited by 7 publications

References 2 publications

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

New Die-Compaction Equations for Powders as a Result of Known Equations Correction: Part 1–Review and Analysis of Various Die-Compaction Equations

Strain hardening of a powder body in pressing

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