Papers by Keyword: Recovery

Abstract: With a view to reverse design of product layer, a tri-level precision model of product-part-functional face based on functional face was organized. The products precision information model was recovered from the 3D model, and the precision design was achieved. The implementation process of precision reconstruction was introduced in detail and a piston fixture was presented as an example for validation.

Abstract: After flooded compartment of submarine, whether or not success of emergency recovery lie on the size of crevasse, the depth and the speed of submarine, and the emergency recovery mode. The paper explains the method of making certain submarine safety limited area, and takes a submarine for example to establish maneuver safety boundary by a great deal numerical simulation under different emergency recovery mode. This will provide scientific theory guide to adopt emergency program for submarine manipulator when encounter submarine accident, and offer logical suggestions to set down a veracious recovery plan.

Abstract: The applicability of a physical model to describe the austenite microstructure evolution after hot deformation in High-Mn steels was investigated. Double-hit torsion tests were carried out to determine the softening behaviour of two High-Mn steels, one of them microalloyed with 0.11 wt% Nb. The values of the unknown parameters included in the model were determined by fitting experimental results. The model describes adequately the softening evolution of the steels. At high temperatures recovery and recrystallization contribute to mechanical softening, the latter having the main contribution. In contrast, when strain-induced precipitation occurs recovery has a larger effect.

Abstract: A technology route of Reverse flotation of acid-consuming gangue mineralsAcid leaching for copperExtractingElectrodepositing is proposed for recovery copper from a tailings with high content of calcium oxide and magnesium oxide and high content of combined copper oxide. The effect of H₂SO₄ concentration, leaching time and stirring speed on copper leaching was investigated. The leaching solution obtained under the optimal copper leaching conditions, was used to be proceeded for extracting and electrodepositing test. The best leaching conditions are stirring speed of 30 m/min, H₂SO₄ concentration of 150 Kg/t ore, leaching time of 30 minutes. Under the best conditions, the acid leaching test presented that the production of per ton copper consumes sulfuric acid of 17.31 t, and Cu leaching rate is 84.70%.

Abstract: The coupling between local texture and microstructure is analyzed during restoration processes in aluminum cold-rolled to high and ultrahigh strains. The deformed microstructure is composed of lamellae with orientations of rolling texture components that occupy different volume fractions and vary in the spatial distribution. The individual lamellae are separated by low and high angle boundaries and significant local differences are produced in the deformed microstructure both in terms of the stored energy and boundary mobility. These differences influence recovery and recrystallization processes, resulting in significant local variations in mechanisms and kinetics of these processes. The observations suggest that the characterization of the local texture and microstructure both in the deformed state and after annealing is important in order to underpin the analysis of recovery and recrystallization on the sample scale.

Abstract: Single crystals of Al-0.1%Mn have been channel-die compressed to a true strain of 2.3 and their recovery behaviour at 240-320°C investigated by microhardness measurements, EBSD microtexture mapping and X-ray line broadening analysis. The crystal orientations are the nominally stable Goss {110}, brass {110} and S {123}. For all three orientations the microhardness decreases with a logarithmic time dependency but the instantaneous recovery rates of the Brass oriented crystals are systematically lower than those of the other two orientations by a factor of about 2. The dislocation densities decrease rapidly in the first stages of recovery (<1 min) by dislocation dipole annihilation and more slowly thereafter. In the Goss and S orientations the later stage of recovery is due to sub-grain growth. The orientation dependency is ascribed to the relatively low misorientations developed by plastic straining in the Brass crystals (average about 4°) compared with the Goss and S orientations (about 7-8°).

Abstract: A phenomenologically new recovery mechanism – triple junction motion is presented. This recovery mechanism is found to be the dominant one at low and medium temperatures in highly strained aluminum, which has a very fine microstructure, composed of lamellae with the thickness of a few hundred nanometers. Triple junction motion leads to removal of thin lamellae and to a consequent increase of the thickness of neighboring lamellae. This recovery mechanism therefore increases the average lamellar boundary spacing and causes a gradual transition from a lamellar structure to a more equiaxed structure preceding recrystallization.

Abstract: Data are presented on the x-ray line broadening distribution over the texture of cold-rolled Nb and Mo sheets. The method of generalized X-ray pole figures, which combine texture measurements with X-ray line profile analysis, is employed. The X-ray line broadening is considered as an indicator of residual deformation effects. It was revealed that these effects in cold-rolled BCC metals rise as the grain orientation shifts away from texture maxima towards texture minima. The intensity of X-ray reflections change during annealing at 200 – 500C and this change correlates with the line broadening. The recrystallization texture of BCC metals is dominated by orientations deflected from the peak maxima by 25 – 30 deg. These orientations in the deformed structure have relatively high stored energy. Their volume fraction is sufficient for them to be able to consume most of the deformed matrix.

Abstract: Microalloying additions are critical for grain size control during thermo-mechanical processing. The addition of niobium is known to delay the onset and growth of recrystallization. A physically-based model for the interaction of strain-induced precipitation, recovery and recrystallization is presented. A key feature of the model is the incorporation of the effect of precipitation on the nucleation of recrystallization. Quantitative agreement between the experimental measurements and the model predictions has also been demonstrated. The model offers valuable insight into the relative contributions of solute and precipitate Nb as well as the optimum conditions for strain accumulation.

Abstract: Motivated by improving current softening models for recycle friendly alloys, softening was investigated in high purity and commercial purity aluminium alloys. Utilizing the electron backscatter diffraction (EBSD) technique, orientation dependent sub-grain growth was characterized with respect to grain size and average boundary misorientation. In the high purity alloys, small additions of Mn in solid solution slowed down the recovery kinetics. The recovery mechanisms were however not altered, but recovery kinetics were found to be orientation dependent. The presence of high angle grain boundaries or transition bands, i.e. large and sharp orientation gradients, seemed to change the growth from slow and continuous to a faster and discontinuous process. This was typical for Cube and Goss, while weak, short and long range orientations gradients observed in Copper, S and Brass, did not alter growth which was slow and continuous. Before detailed studies of recovery of the commercial purity alloy were initiated, a rather slow recovery was observed and further investigated. Preliminary results indicate that iron in solid solution is dramatically slowing down the kinetics but can form clusters by an intermediate annealing in order to speed up recovery.