The relationship between fracture toughness and microstructure in the cleavage fracture of mild steel

Curry, David; Knott, J. F.

doi:10.1179/030634576790431453

Cited by 174 publications

(36 citation statements)

References 8 publications

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“…Experimental verification of the H-P-type prediction in equation (4.2) was demonstrated for a compilation of iron and steel measurements [65,[73][74][75][76][77]. The large plastic zone sizes associated with the measurements were found to be relatively independent of the material grain size.…”

Section: Crack Size In Fracture Mechanicsmentioning

confidence: 99%

Material grain size and crack size influences on cleavage fracturing

Armstrong

2015

Phil. Trans. R. Soc. A.

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A review is given of the analogous dependence on reciprocal square root of grain size or crack size of fracture strength measurements reported for steel and other potentially brittle materials. The two dependencies have much in common. For onset of cleavage in steel, attention is focused on relationship of the essentially athermal fracture stress compared with a quite different viscoplastic yield stress behaviour. Both grain-size-dependent stresses are accounted for in terms of dislocation pile-up mechanics. Lowering of the cleavage stress occurs in steel because of carbide cracking. For crack size dependence, there is complication of localized crack tip plasticity in fracture mechanics measurements. Crack-size-dependent conventional and indentation fracture mechanics measurements are described also for results obtained on the diverse materials: polymethylmethacrylate, silicon crystals, alumina polycrystals and WC-Co (cermet) composites.

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Section: Crack Size In Fracture Mechanicsmentioning

confidence: 99%

Material grain size and crack size influences on cleavage fracturing

Armstrong

2015

Phil. Trans. R. Soc. A.

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“…Terdapat beberapa studi melakukan penelitian tentang efek dari parameter proses Carburizing, seperti temperatur quenching, waktu tahan (holding time), temperatur tempering, dan waktu pendinginan yang menggunakan media pendingin oli [10][11][12][13][14]. Proses Pack Carburizing merupakan proses pengerasan permukaan material yang dilakukan menggunakan kotak besi tahan panas dengan penambahan karbon aktif.…”

Section: Gambar 1 Skema Proses Carburizingunclassified

Pengaruh Variasi Karbon Aktif dan Waktu Tahan Terhadap Kekerasan Material JIS G-3123 Menggunakan Metode Pack Carburizing

Sakura

Suheni

Iskandar

2017

R.E.M. (Rekayasa Energi Manufaktur) Jurnal

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ABSTRAKPerbaikan sifat mekanik dari material logam merupakan hal penting di dunia Industri. Sifat mekanik pada material yang paling banyak dibutuhkan di dunia Industri yaitu kekuatan dan ketahanan gesek. Proses Carburizing, merupakan proses pengerasan permukaan dengan penambahan unsur karbon pada permukaan material. Proses Carburizing pada baja JIS G-3123 dilakukan dengan metode Pack Carburizing dengan variasi berat karbon aktif 125 gram, 250 gram, dan 400 gram dengan waktu tahan selama 30 menit, 45 menit, dan 60 menit. Penelitian pengaruh variasi penambahan karbon aktif dan waktu tahan terhadap kekerasan pada material JIS G-3123 menggunakan metode Pack Carburizing, diperoleh nilai kekerasan tertinggi yaitu 463,550 kg/mm2 dengan berat karbon aktif 400 gram dan waktu tahan 30 menit. Semakin tinggi berat karbon aktif pada proses carburizing, maka nilai kekerasan material akan semakin tinggi pula, dengan waktu tahan yang paling rendah. Kata kunci: pack carburizing, kekerasan vickers, JIS G-3123, karbon aktif, waktu tahan. ABSTRACT

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“…This presented some difficulties when comparisons were made with the theoretical analysis of Smith [16], which predicted no effect of grain size, per se. The dilemma was resolved by a set of experiments [13] carried out to demonstrate that, in simplycooled mild steels, carbide thickness increased monotonically with grain size, so that the variation of σ F with 'grain size' was, in fact, a reflection of the variation of σ F with carbide thickness, 2c as predicted by equation (5.2). Further studies on spheroidal carbide distributions showed that σ F was related in a linear fashion to c −0.5 as predicted by equation (5.3), and that the 'effective work of fracture, γ p ', was approximately 8-14 Jm −2 .…”

Section: Microstructural Features Of Transgranular Cleavagementioning

confidence: 99%

“…The critical tensile stress criterion has been used to explain the values of fracture toughness, Curry & Knott [13][14][15] …”

Section: Slow Notched-bend Tests and Fracture Toughness Valuesmentioning

confidence: 99%

Brittle fracture in structural steels: perspectives at different size-scales

Knott

2015

Phil. Trans. R. Soc. A.

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This paper describes characteristics of transgranular cleavage fracture in structural steel, viewed at different size-scales. Initially, consideration is given to structures and the service duty to which they are exposed at the macroscale, highlighting failure by plastic collapse and failure by brittle fracture. This is followed by sections describing the use of fracture mechanics and materials testing in carryingout assessments of structural integrity. Attention then focuses on the microscale, explaining how values of the local fracture stress in notched bars or of fracture toughness in pre-cracked test-pieces are related to features of the microstructure: carbide thicknesses in wrought material; the sizes of oxide/silicate inclusions in weld metals. Effects of a microstructure that is 'heterogeneous' at the mesoscale are treated briefly, with respect to the extraction of test-pieces from thick sections and to extrapolations of data to low failure probabilities. The values of local fracture stress may be used to infer a local 'work-of-fracture' that is found experimentally to be a few times greater than that of two free surfaces. Reasons for this are discussed in the conclusion section on nano-scale events. It is suggested that, ahead of a sharp crack, it is necessary to increase the compliance by a cooperative movement of atoms (involving extra work) to allow the crack-tip bond to displace sufficiently for the energy of attraction between the atoms to reduce to zero.

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The relationship between fracture toughness and microstructure in the cleavage fracture of mild steel

Cited by 174 publications

References 8 publications

Material grain size and crack size influences on cleavage fracturing

Material grain size and crack size influences on cleavage fracturing

Pengaruh Variasi Karbon Aktif dan Waktu Tahan Terhadap Kekerasan Material JIS G-3123 Menggunakan Metode Pack Carburizing

Brittle fracture in structural steels: perspectives at different size-scales

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