Measurement of flow stress in hot plane strain compression tests

Loveday, M S; Mahon, G. J.; Roebuck, B; Lacey, A. J.; Palmiere, E.J.; Sellars, C. M.; Winden, M.R. van der

doi:10.1179/mht.2006.006

Cited by 43 publications

(27 citation statements)

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“…Plane strain compression (PSC) specimens, having a geometry 60 mm long Â 30 mm wide Â 10 mm high, were machined from the hot-rolled plate. PSC testing was performed using the thermomechanical compression (TMC) machine at The University of Sheffield [16]. Samples were reheated to 1100°C, held for 30 s and then force-air cooled to the deformation temperature of 850°C.…”

Section: Compositions and Processing Conditionsmentioning

confidence: 99%

Dissolution and precipitation behaviour in steels microalloyed with niobium during thermomechanical processing

2015

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Section: Compositions and Processing Conditionsmentioning

confidence: 99%

Dissolution and precipitation behaviour in steels microalloyed with niobium during thermomechanical processing

2015

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“…Although the values used in this work might be inaccurate, they rely on expertise built over many years of testing aluminium alloys and steels and applying the friction correction to flow stress calculations. Results from Loveday et al, 2006 on the same aluminium alloy tested under very similar deformation conditions show variations of less than 10 MPa in flow stress values by varying the friction coefficient within a relevant range. Results on a stainless steel from the same paper also show that the effect of the friction coefficient is very noticeable at large strain due to changes in friction conditions at the contact surface between the anvil and the specimen after extensive deformation, but is very limited for small strain values such as that (15%) used to deform Fe-30wt%Ni at 1000 C in this work.…”

Section: Discussionmentioning

confidence: 88%

“…2, h 0 /w 0.67 and l/w ! 3, with b 0 and h 0 being the initial breadth and thickness of the specimen before deformation, w the width of the platen and l the length of the specimen along RD (Loveday et al, 2006). Platens applying the compression are 15 mm wide.…”

Section: Methodsmentioning

confidence: 99%

“…Graphite is commonly used as lubricant between the specimen and platens for temperatures below 800 C. A friction coefficient of 0.1 was estimated (Loveday et al, 2006) for the friction correction used to compute flow stress values from the measured average pressure p applied by the platens to the specimen. This correction procedure (Silk and van der Winden, 1999) firstly assumes partially sticking/sliding conditions along the contact line between specimen and platen and calculates the position z 0 from the edge of the anvil of the boundary between sticking and sliding conditions using the following equation:…”

Section: Methodsmentioning

confidence: 99%

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Assessment of crystal plasticity finite element simulations of the hot deformation of metals from local strain and orientation measurements

Pinna

Lan

Kiu

et al. 2015

International Journal of Plasticity

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a b s t r a c tSimulations of the deformation of microstructures at high homologous temperatures have been carried out using a Crystal Plasticity Finite Element (CPFE) model to predict texture and grain structure deformation in Face-Centred-Cubic (FCC) metals deformed under conditions representative of hot forming operations. Results show that the model can quantitatively predict the location and intensity of the main deformation texture components of a AA5052 aluminium alloy deformed at 300 C under Plane Strain Compression (PSC). Simulations also reasonably predict the range of strain values measured using microgrids in the microstructure of a Fe-30wt%Ni alloy deformed at 1000 C using a new experimental procedure. However, the model fails to reproduce accurately intra-granular strain distribution patterns. Results at room temperature, after a tensile test carried out inside a Scanning Electron Microscope (SEM) on the same model alloy, show a much closer match between simulation and experimental results. Despite discrepancies for some local deformation features, the model predicts the formation of intense deformation bands running at 45 with respect to the tensile axis and located along the same grain boundaries as in the experiment. Results, therefore, highlight the limitations of deterministic CPFE simulations for situations where the grain size to sample thickness ratio is small and for which the sub-surface grain geometry strongly affects surface strains. They also show that reliable predictions of the statistical response of a polycrystalline aggregate can be obtained for the hot deformation of metals which controls microstructure evolution during the processing of metals.

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“…The force (F) and displacement (d) were converted to equivalent stress (s) and strain ( 3) and once the calculation of s and 3 were done, it was possible to obtain the mean flow stress for each test using the procedure described in literature [23,24]. Cylindrical samples of 5 mm in length and 3.5 in mm diameter were cut from the rolled sheet and were tested in a quench dilatometer to determine the transformation temperatures.…”

Section: Methodsmentioning

confidence: 99%