Hamilton, Canada
Hamilton, Canada

Time filter

Source Type

Kang J.,CanmetMATERIALS | Mishra R.K.,General Motors | Wilkinson D.S.,McMaster University | Hopperstad O.S.,Impact Lab | Hopperstad O.S.,Norwegian University of Science and Technology
Philosophical Magazine Letters | Year: 2012

Experimental measurements of stress drops and band strains in type-B Portevin-Le Chatelier (PLC) bands were carried out for 5xxx series Al-Mg sheets with Mg content between 1.8 and 4.5wt%. While the stress drops increase with global strain, the band strain values in all the samples follow a common linear relationship with global strain. The results indicate that the type-B PLC band strain is independent of solute content at given strain rate. © 2012 Copyright Taylor and Francis Group, LLC.

Irina P.,CanmetMATERIALS | Haiou J.,CanmetMATERIALS
Materials Science Forum | Year: 2016

New Al-Mg alloys have been developed for super-plastic forming (SPF) based on commercial AA5083/AA5086 alloys, but with an increased Mn content from 0.5 to 1.5 wt.% and a decreased impurity Fe level from 0.25 to 0.05 wt.%.The effects of Mn and Fe levels on superplasticity have been investigated by high temperature tensile testing of cold rolled H18 sheets at 425 to 525°C with a strain rate of 2×10-3 s-1. The microstructure evolution during different processing stages, grain size and grain size stability were investigated by optical microscopy and scanning electron microscopy. Both Mn and Fe showed a similar and significant contribution to grain size control in recrystallization, but their effect on high temperature sheet formability was different. An increase in Mn level led to an improvement in high temperature tensile elongation, while an increase in Fe content reduced the sheet formability. A new alloy with 1.5 wt.% Mn and 0.05 wt.% Fe, when processed to H18 temper, was able to reach more than 400% tensile elongation at 450 - 500°C with a strain rate of 2×10-3 s-1. © 2016 Trans Tech Publications, Switzerland.

Shokrollahi Yancheshmeh M.,Laval University | Radfarnia H.R.,CanmetMATERIALS | Iliuta M.C.,Laval University
Journal of Natural Gas Science and Engineering | Year: 2016

Calcium looping process, on the basis of the reversible reaction between CaO and CO2, is a promising technology for capture of CO2 from different gas streams. The performance of CO2 sorbents could be easily influenced by the gas stream composition. As the exhaust gas stream generally contains a considerable amount of steam, a good understanding of its side effects on the performance of CaO-based sorbents is essential. However, there is not consensus on the mechanism with which the presence of steam during carbonation influences the CO2 capture performance and contradictory results have been reported regarding the effect of steam addition during calcination. This work aims to investigate the effect of steam addition during either carbonation or calcination on the reactivity of a home-made synthetic CaO sorbent containing 78 wt% CaO and 22 wt% Ca9Al6O18. Various concentrations of steam up to 9.5 vol% were provided during either carbonation or calcination for 15 carbonation-calcination cycles (carbonation: 650 or 550 °C; calcination: 800 °C). The morphology changes of the sorbent after cyclic carbonation-calcination experiments were studied in detail at different operating conditions. It was concluded that the sorbent reactivity was significantly increased for all concentrations of steam injected during carbonation step, due to the accelerated solid-state diffusion and steam catalysis. In case of steam addition during calcination, the carbonation performance was affected negatively or positively depending on the concentration of steam in the gas stream. For 2.3 vol% steam injection, the sorbent reactivity was worsened, while the presence of 9.5 vol% steam increased the CO2 capture capacity during 9 initial cycles. Such behavior was attributed to the intensified material sintering in the presence of steam during calcination step, which results in the formation of large pores and the decrease of specific surface area. © 2016 Elsevier B.V.

Simha C.H.M.,CanmetMATERIALS | Adibi-Asl R.,University of Toronto
Journal of Pressure Vessel Technology, Transactions of the ASME | Year: 2015

It is shown that the extended variational theorem of Mura et al. (1965, "Extended Theorems of Limit Analysis," Q. Appl. Math., 23(2), pp. 171-179) can be applied to structures subjected to more than one load and be used to compute lower bound limit load multipliers. In particular, the multiplier proposed by Simha and Adibi-Asl (2011, "Lower Bound Limit Load Estimation Using a Linear Elastic Analysis," ASME J. Pressure Vessel Technol., 134(2), p. 021207), which can be computed using an elastic stress field, is shown to be a lower bound. Furthermore, it is demonstrated that lower bound limit load for cracked structures may also be computed using a subvolume selection method. No iterations or elastic modulus adjustment are required. Several analytical and numerical examples that illustrate the procedure are presented. Copyright © 2015 by ASME.

Muhammad W.,University of Waterloo | Mohammadi M.,University of Waterloo | Kang J.,CanmetMATERIALS | Mishra R.K.,General Motors | Inal K.,University of Waterloo
International Journal of Plasticity | Year: 2015

Abstract Deformation twinning and texture evolution in hexagonal close-packed (HCP) metals lead to evolving flow stress asymmetry/anisotropy and evolving plastic anisotropy. These phenomena cause a significant change in the shape of the yield surface with accumulated plastic deformation which cannot be modeled accurately with traditional hardening laws. In this paper, an anisotropic continuum-based plasticity model is proposed to capture the large strain cyclic hardening behavior of magnesium alloys. Key in the current formulation is the incorporation of distortional hardening to model the evolving asymmetric/anisotropic hardening response of magnesium alloys for both monotonic and reverse loading paths. The hardening behavior is classified into three deformation modes: Monotonic Loading [ML], Reverse Compression [RC], and Reverse Tension [RT]. The deformation modes correspond to the different loading regimes of the cyclic hardening curve. Specifically, the ML mode corresponds to the initial in-plane tension and the initial in-plane compression from the annealed state, the RC mode corresponds to the in-plane compression following previous tension and the RT mode corresponds to the in-plane tension following previous compression. Three separate hardening laws are used to define the hardening response within each deformation mode. Moreover, a multi-yield surface modeling approach is used where a CPB06 type anisotropic yield surface is assigned to each deformation mode. The evolution of the anisotropy coefficients involved in the expression of the yield function, is considered to model distortional hardening within each deformation mode. The evolving anisotropy parameters are found by minimizing the difference between the model predictions and the experiments, together with the interpolation technique proposed by Plunkett et al. (2006). The proposed model is calibrated using monotonic and reverse loading experimental data for AZ31B and ZEK100 magnesium alloys. A strain rate independent elasto-plastic formulation is used to implement the proposed constitutive model as a user material subroutine (UMAT) in the commercial finite element software LS-DYNA®. The predictions of the model are compared against the experimental monotonic and cyclic (CTC and TCT) flow stresses and r-values of AZ31B and ZEK100 sheets along different test directions. An excellent agreement is found between the simulated and experimental results. © 2015 Elsevier Ltd. All rights reserved.

Kang J.,CanmetMATERIALS | Gong K.,Constellium
ASTM Special Technical Publication | Year: 2015

The dependence of fracture strain on stress triaxiality has been recently recognized as an important factor that controls the fracture of aluminum alloys. A number of experimental programs have been reported to determine fracture strains in a wide range of stress triaxiality using a variety of types of specimens. However, because of the lack of direct measurement of local strains near the fracture zone, indirect estimations of fracture strain are commonly used. The errors in determining fracture strain are uncertain. In this study we use the digital image correlation (DIC) method to determine the fracture strains in AA6060 aluminum extrusion material. This material is often used in automotive crash management systems. A commercially available DIC system was used to follow the deformation occurring during the tests of a set of newly designed specimens with a wide range of stress triaxiality; thus, the inception of instability and fracture can be captured and distinguished precisely. More importantly, post-experiment analysis in DIC allows strain calculations at macroscopic levels at varying step sizes, thus, the dependence of fracture strain on gauge length has been determined in each testing condition. The fracture locus of AA6060 aluminum extrusion has been successfully determined and the concept of "scaled fracture strain" has then been proposed to ensure consistency of the fracture locus in both the experiment and in modeling. © Copyright 2015 by ASTM International.

Hosokawa A.,McMaster University | Hosokawa A.,Japan National Institute of Materials Science | Wilkinson D.S.,McMaster University | Kang J.,CanmetMATERIALS | Maire E.,INSA Lyon
Acta Materialia | Year: 2013

Void growth and coalescence in model materials containing a pre-existing three-dimensional void array were studied by X-ray computed tomography coupled with in situ uniaxial tensile deformation. A newly developed continuous tomography technique was employed to capture the onset of coalescence. Using a picosecond laser machining system and a diffusion bonding technique, model materials with different void geometries were prepared. By implementing continuous tomography, the plastic strain at the onset of void coalescence was measured (instead of simple linkage) for the first time. The plastic strains at the onset of void coalescence were compared with the existing void coalescence models. Finite-element (FE) simulations were performed to study the influences of void shape (sphere, cylinder, tapered-cylinder) on the void growth behavior. This study shows that the coalescence models developed by Thomason and later extended by Pardoen and Hutchinson provide accurate predictions of coalescence strain when the voids are aligned normal to the tensile axis. However, offsets can induce shear effects that lower the coalescence strain in a manner not predicted by the models. Two-dimensional plane-strain FE simulations were also used to explore the influence of shear localization between two misaligned coalescing voids on ductility. These demonstrate the nature of the effect. © 2012 and Elsevier Ltd. Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Hosokawa A.,Japan National Institute of Materials Science | Wilkinson D.S.,McMaster University | Kang J.,CanmetMATERIALS | Kobayashi M.,Toyohashi University of Technology | Toda H.,Toyohashi University of Technology
International Journal of Fracture | Year: 2013

The influences of work hardening behavior of materials on ductile fracture, and especially on void growth and coalescence, have been investigated in model materials by in-situ X-ray computed tomography (XCT) coupled with tensile deformation. The model materials contain an artificial void array embedded in a metal matrix. By producing such materials with different metal matrices (pure copper, brass, Glidcop = copper strengthened by Al2O3 nanoparticles), the influences of the work hardening behaviors on void growth and coalescence/linkage process are analyzed. This set of experiments were performed at Japanese synchrotron radiation facility SPring-8 BL20XU beamline, whereby the X-ray tomography setup with one of the highest spatial resolution in the world is available. This beamline however provides less brilliant X-rays compared to the ESRF ID15 beamline where the our previous experiments were performed Hosokava et al. (Acta Mater, 60:2829-2839, 2012), (Acta Mater, 61:1021-1036, 2013). To compensate for the X-ray absorption problems, the specimens to be tested have to be much smaller, making the experiments more difficult. Nevertheless, the growth and linkage behaviors of the artificial voids were successfully visualized, and the plastic strain whereby the linkage takes place (referred to as the linkage strain, hereafter) were quantitatively captured. The models for void coalescence developed by Thomason and by Pardoen and Hutchinson both predict coalescence rather well for both brass and Glidcop, even though the linkage events were found to be dominated by the meso/macro shear localization process. © 2013 Springer Science+Business Media Dordrecht.

Zeng Y.,CanmetMATERIALS | Guzonas D.,Chalk River Laboratories
JOM | Year: 2016

The supercritical water-cooled reactor (SCWR) is an innovative next generation reactor that offers many promising features, but the high-temperature high-pressure coolant introduces unique challenges to the long-term safe and reliable operation of in-core components, in particular the fuel cladding. To achieve high thermal efficiency, the Canadian SCWR concept has a coolant core outlet temperature of 625°C at 25 MPa with a peak cladding temperature as high as 800°C. International and Canadian research programs on corrosion issues in supercritical water have been conducted to support the SCWR concept. This paper provides a brief review of corrosion in supercritical water and summarizes the Canadian corrosion assessment work on potential fuel cladding materials. Five alloys, SS 347H, SS310S, Alloy 800H, Alloy 625 and Alloy 214, have been shown to have sufficient corrosion resistance to be used as the fuel cladding. Additional work, including tests in an in-reactor loop, is needed to confirm that these alloys would work as the fuel cladding in the Canadian SCWR. © 2015, Her Majesty the Queen in Right of Canada.

Kang J.,CanmetMATERIALS | Shen G.,CanmetMATERIALS
ASTM Special Technical Publication | Year: 2014

Various shear tests have been proposed over decades leading to the publication of the ASTM Standard B831-93 [ASTM B831-93: Standard Test Method for Shear Testing of Thin Aluminum Alloy Products, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2011] and its latest revision B831-11 for shear test of aluminum alloy thin sheet materials. However, this standard only measures the shear strength of aluminum sheets. A new shear specimen design has been developed by Kang et al. [Kang, J., Wilkinson, D. S., Wu, P. D., Bruhis, M., Jain, M., Embury, J. D., and Mishra, R., "Constitutive Behavior of AA5754 Sheet Materials at Large Strains," J. Eng. Mater. Technol., Vol. 130, No. 3, 2008, p. 031004]. We propose using digital image correlation for shear strain measurements, which is impractical for conventional extensometry techniques. A new shear test method is then used to measure both the shear strength and shear stress-shear strain curves up to large strains. 3D finite element analysis (FEA) was carried out for both the standard and new shear specimen designs. The results show that simple shear state is reached within the shear zone. The results also reveal that the out-of-plane shear strain is significantly reduced to 5 % in new shear specimen design compared to that of over 12 % for the standard specimen design. The rotation of the end of the shear zone is, thus, prevented. Copyright © 2014 by ASTM International.

Loading CanmetMATERIALS collaborators
Loading CanmetMATERIALS collaborators