Ductilisation of tungsten (W) through cold-rolling: R-curve behaviour

Reiser, J.; Wurster, Stefan; Hoffmann, J.; Bonk, Simon; Bonnekoh, Carsten; Kiener, Daniel; Pippan, Reinhard; Hoffmann, Andreas; Rieth, M.

doi:10.1016/j.ijrmhm.2016.03.006

Cited by 48 publications

(11 citation statements)

References 35 publications

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“…alloys and ≈ 95% higher at 97W. [19,29,37,39] are similar to those observed in our RT toughness tests, as seen in Fig. 8d.…”

Section: Microhardness and Tensile Testssupporting

confidence: 89%

“…Other solutes, like Ta, V, Mo, Os, Ti and Cr, generally have negligible to negative effects on W ductilization [1,[15][16][17]. Grain refinement by rolling, severe plastic deformation (SPD), and oxide dispersion stabilization, generally improves W ductility to some extent, but has mixed effects on toughness [6][7][8][9]19]. However, such deformation processing paths result in highly anisotropic properties and textured microstructures, and are otherwise likely unsuitable for fabricating complex components [1,[6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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On the remarkable fracture toughness of 90 to 97W-NiFe alloys revealing powerful new ductile phase toughening mechanisms

Alam

Odette

2020

Acta Materialia

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Tungsten is generally too brittle to serve a robust structural function. Here, we explore the fracture toughness of 90 to 97 wt.%W Fe-Ni liquid phase sintered tungsten heavy alloys (WHAs). The room temperature (RT) maximum load fracture toughness (KJm ≈ 69 to 107 MPa√m) of the WHA, containing only 3 to 10 wt.% of a Ni-Fe ductile phase (DP), is ≈ 9 to 13 times higher than KIc typical of monolithic W (≈ 8 MPa√m). All the WHAs show extensive stable crack growth, and increasing blunting line toughness averaging ≈ 170 MPa√m, prior to significant crack extension. In contrast to classical ductile phase toughening, that is primarily due to macrocrack bridging, the WHA toughness increase mainly involves new mechanisms associated with arrest, blunting and bridging of numerous dilatational shielding process zone microcracks in the macrocrack process zone. Tests down to-196°C, to partially emulate irradiation hardening, show decreasing toughness and a transition to elastic fracture at a temperature of-150°C for 90W to-25ºC for 97W. However, even at-196°C, the leanest DP 97W WHA KIc is ≈ 3 times that of monolithic W at RT. Possible effects of the small specimen size used in this study are briefly summarized.

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“…alloys and ≈ 95% higher at 97W. [19,29,37,39] are similar to those observed in our RT toughness tests, as seen in Fig. 8d.…”

Section: Microhardness and Tensile Testssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

On the remarkable fracture toughness of 90 to 97W-NiFe alloys revealing powerful new ductile phase toughening mechanisms

Alam

Odette

2020

Acta Materialia

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“…Where is the maximum load during stable crack growing, is the distance between the support pins, is the sample width, is the sample thickness, is the stable crack length which equals to the pre-notch length plus the crack extension length, the function ( / ) is described in ASTM E399: A rising R-curve indicates that, for a further crack opening, the crack driving force needs to be increased, which hints towards defect tolerance. Typically, ductile materials [28] or composite materials with proper reinforcement exhibit a rising R-curve. For composite materials, it is created by fiber bridging causing mechanical interlocks.…”

Section: In-situ 3-point Bending Testmentioning

confidence: 99%

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

et al. 2019

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In future fusion reactors, tungsten is considered as the main candidate material for plasma-facing components. However, the intrinsic brittleness of tungsten is of great concern during operation. To overcome this drawback, tungsten fiber-reinforced tungsten composites (Wf/W) are being 2 developed relying on extrinsic toughening principles. Tungsten (W) fibers with extremely high tensile strength and ductility are used to reinforce a tungsten matrix. In this work, field assisted sintering technology (FAST) is used to produce Wf/W material. Mechanical characterizations including Charpy impact and 3-point bending tests are performed. Based on the 3-point bending test results, the Wf/W materials can facilitate a promising pseudoductile behavior even at room temperature, similar to fiber reinforced ceramic composites. Fracture energy density and fracture toughness together with the crack-resistance curves (R-curves) are measured. Compared to conventional pure tungsten, Wf/W shows significant improvement in fracture toughness.

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“…This approach is based on the fact that with the stable development of cracks there is a continuous balance between the force G(S) and the resistance R(S) of course, the concept of R-characteristics [8,9] has a number of advantages, but it is not without drawbacks. The main disadvantages are that this concept applies only to rectilinear cracks and does not take into account the time-varying impulse load and the effect of crack speed on R(S).…”

Section: Fig 1 Conditional Body With a Crackmentioning

confidence: 99%

Analysis of cracks development in rock massif with the use of dynamic destruction resistance

Bakhtyn¹

2021

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The object of research: the process of development of main cracks in the massif of rocks under the action of a wave impulse taking into account the dynamic destruction resistance. Investigated problem: Description of the dynamics of crack development in the impulse mode of increasing their size, as well as the transition to an unstable mode of crack growth. The main scientific results: In the present article uses an approach based on the principle of least action and N-characteristic of dynamic crack growth resistance. This allowed to obtain analytical equations of the crack growth trajectory in the rock massif and the main characteristics of the process. The area of practical use of the research results: The considered approach allows to predict the formation of the shear surface in quarries and natural slopes. This approach also allows to set a time-varying probability of their steady state and adjust, if necessary, the parameters of blasting. Innovative technological product: Analytical regularities for the driving force of the crack and dynamic destruction resistance are obtained, which take into account the velocity and acceleration of the crack, as well as the time and nonstationarity of the impulse load. Scope of the innovative technological product: The proposed approach can be used in the design of blasting operations in quarries and in the calculation of the probabilities of the steady state of natural massifs under the influence of impulse loads.

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Ductilisation of tungsten (W) through cold-rolling: R-curve behaviour

Cited by 48 publications

References 35 publications

On the remarkable fracture toughness of 90 to 97W-NiFe alloys revealing powerful new ductile phase toughening mechanisms

On the remarkable fracture toughness of 90 to 97W-NiFe alloys revealing powerful new ductile phase toughening mechanisms

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

Analysis of cracks development in rock massif with the use of dynamic destruction resistance

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