Modelling the Recrystallization Behaviour during Industrial Processing of Aluminium Alloys

2012 ◽  
Vol 715-716 ◽  
pp. 543-548 ◽  
Author(s):  
Knut Marthinsen ◽  
Jesper Friis ◽  
Bjørn Holmedal ◽  
Inge Skauvik ◽  
Trond Furu
Keyword(s):  
Dislocation Density ◽  
Aluminium Alloys ◽  
Alloy Composition ◽  
Subgrain Size ◽  
Composition Profile ◽  
Hardening Model ◽  
Subsequent Recovery ◽  
Industrial Processing ◽  
Work Hardening Model ◽  
Particle Paths

The microstructure evolution in commercial AlMgSi alloys during and after extrusion of a simple U-shaped profile has been modelled. The strain, strain rate and temperature along a set of particle paths are taken from FE-HyperXtrude simulations and used as input to the work hardening model ALFLOW, to predict the evolution of the subgrain size and dislocation density during deformation. As soon as the profile leaves the die, the subsequent recovery and recrystallization behaviour is modelled with the softening model ALSOFT. This procedure enables the modelling of recrystallization profiles, i.e. the fraction recrystallized through the wall thickness of the extruded profile. The sensitivity to chemistry (alloy composition), profile deflection and the cooling rate at the die exit has been investigated by means of a set of generic modelling cases.

Modelling Nucleation of Recrystallisation in Aluminium Alloys

2007 ◽  
Vol 550 ◽  
pp. 85-94 ◽  
Author(s):  
C. Schäfer ◽  
Mischa Crumbach ◽  
Günter Gottstein
Keyword(s):  
Growth Model ◽  
Work Hardening ◽  
Aluminium Alloys ◽  
Deformation Texture ◽  
Process Modelling ◽  
Hardening Model ◽  
Texture Model ◽  
Nucleation Mechanisms ◽  
Work Hardening Model

The predictions from a grain cluster deformation texture model, GIA, are utilized to study the nucleation texture of recrystallisation of aluminium alloys. In combination with a dislocation based work hardening model, the propensity of specific grains in their granular environment for select nucleation mechanisms is investigated. Quantitative criteria for the nucleation events can be formulated. The results can be fed into a growth model of recrystallisation to predict recrystallisation textures and lend themselves to through-process modelling.

Recovery in 15%Cr Ferritic Stainless Steel after Large Strain Deformation

2007 ◽  
Vol 558-559 ◽  
pp. 119-124
Author(s):  
Andrey Belyakov ◽  
Kaneaki Tsuzaki ◽  
Yoshisato Kimura ◽  
Yoshinao Mishima
Keyword(s):  
Stainless Steel ◽  
Low Temperature ◽  
Dislocation Density ◽  
Ambient Temperature ◽  
Ferritic Stainless Steel ◽  
Vickers Hardness ◽  
Subgrain Size ◽  
Large Strain ◽  
Internal Stresses ◽  
Cumulative Strain

15%Cr ferritic stainless steel was machined in rectangular samples and then processed by multiple forging to a total cumulative strain of 7.2 at an ambient temperature. The large strain deformation resulted in almost equiaxed submicrocrystalline structure with a mean grain/subgrain size of 230 nm and about 2.2×1014 m-2 dislocation density in grain/subgrain interiors. The annealing at a relatively low temperature of 500oC did not lead to any discontinuous recrystallizations. The grain/subgrain size and the interior dislocation density slightly changed to 240 nm and 2.1×1014 m-2, respectively, after annealing for 30 min, while the Vickers hardness decreased from 3140 MPa in the as-processed state to 2900 MPa. This annealing softening was attributed to remarkable release (by 50%) of internal stresses, which are associated with a non-equilibrium character of strain-induced grain/subgrain boundaries.

Microstructural Aspect of Ageing Process of GP91 Cast Steel

2013 ◽  
Vol 203-204 ◽  
pp. 368-371
Author(s):  
Grzegorz Golański ◽  
Joanna Kępa
Keyword(s):  
Dislocation Density ◽  
Power Plants ◽  
Subgrain Size ◽  
Ageing Time ◽  
Cast Steel ◽  
Phase Identification ◽  
Tem Analysis ◽  
Steel Microstructure ◽  
Mean Diameter ◽  
Microstructural Aspect

The microstructure of 9% Cr cast steel for advanced power plants, serviced at around 580 − 600°C, after ageing has been characterized. The investigated cast steel was subject to ageing at the temperature of 600°C for 6000 and 8000 hrs. Quantitative TEM analysis of the cast steel microstructure was performed to describe the dislocation density within subgrains, the width of martensite subgrains and the M23C6 carbides parameters (shape and mean diameter). Moreover, the phase identification was carried out using electron diffraction. The results have shown that an increase in ageing time at 600°C temperature is the reason for slight increase in the subgrain size, the size of M23C6 carbides and a decrease in dislocation density within subgrains. The MX particle size was not changed. The Laves phase was identified in the cast steel microstructure after 6000 hrs of ageing.

A work-hardening model of the lower yield strength of discontinuously yielding alloys: Ni3Al and mild steel

1989 ◽  
Vol 4 (3) ◽  
pp. 470-472 ◽  
Author(s):  
E. M. Schulson
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Mild Steel ◽  
Work Hardening ◽  
Lower Yield ◽  
Hardening Model ◽  
Lower Yield Strength ◽  
Work Hardening Model ◽  
Lüders Bands

The lower yield strengths of Ni3Al and mild steel and their respective relationships to (grain size)−0.8 and (grain size)−0.5 are explained in terms of work hardening within Lüders bands.

Measurement and Control of The Indium Composition Profile Near The InGaAs on GaAs Interface During Mbe

1995 ◽  
Vol 379 ◽  
Author(s):  
Ron Kaspi ◽  
Keith R. Evans
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Alloy Composition ◽  
Composition Profile ◽  
Indium Composition ◽  
And Control ◽  
Measurement And Control

ABSTRACTThe compositional abruptness at both the normal and the inverted InGaAs/Ga(Al)As interface is inherently limited by the surface segregation of In atoms during molecular beam epitaxy. We find, for example, that the intended alloy composition in In0.22Ga0.78As layers is not reached until nearly 35 Å from the normal InGaAs on GaAs interface for growth at 500 °C. We propose and demonstrate a scheme to control and eliminate the compositionally graded region at the normal interface by the artificial formation of an In surface segregated layer (predeposition) prior to the growth of InGaAs.

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