| 1. |
- Beheshti, Reza, et al.
(author)
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Modeling and simulation of isothermal reduction of a single hematite pellet in gas mixtures of H2 and CO
- 2014
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In: TMS 2014 143rd Annual Meeting & Exhibition, Annual Meeting Supplemental Proceedings. - Hoboken, NJ, USA : The Minerals, Metals, and Materials Society. - 9781118889725 ; , s. 495-502
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Conference paper (peer-reviewed)abstract
- In the present project a time dependent computerized model that fairly accurately simulates the isothermal reduction of a hematite pellet with the use of CO and H2 gas mixtures have been developed. The model, which is based on the Shrinking Core Model (SCM), allows for the description of the chemical reactions taking place and the mass transfer conditions existing for each of the gas species present within the pellet. The equations used to describe the different steps are numerically solved with 1D axial symmetric Finite Element Modeling (FEM) using the commercial COMSOL 4.3b software. Small-scale laboratory experiments were also performed under well-controlled conditions to get an understanding for the weight loss of the pellets as a function of time. The results obtained from these experiments were incorporated into the model. The developed model clearly shows some deviations from the experimental results, but this is believed to be due to the existing variations in the shape and size of the pellets, the porosity distribution and the pelletizing history of the industrial pellets.
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| 2. |
- Chai, Guocai
(author)
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Fatigue Crack Initiation in Metallic Matrix
- 2014
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In: TMS 2014 SUPPLEMENTAL PROCEEDINGS. - : John Wiley & Sons. - 9781118889855 - 9781118889725 ; , s. 647-654
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Conference paper (peer-reviewed)abstract
- This paper will provide a study on the behaviors of fatigue crack initiation in metal matrix in five metallic materials using very high cycle fatigue testing and electron microscopy with electron backscatter diffraction and electron channeling contrast technique. The damage and crack initiation mechanisms in metal matrix have been focused. It shows that straining in these materials during the fatigue process was highly localized. This strain localization has led to the damage or fatigue crack initiation at grain boundaries or twin boundaries by impingement cracking. High strain localization causes dislocation accumulation during each cyclic straining and consequently the formation of local "fine grain zone" that increases the local damage by plasticity exhaustion. This can cause the formation of fatigue crack origin in the matrix. Strain localization and local plasticity exhaustion can be used to explain this phenomenon.
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| 3. |
- Dini, Hoda, 1984-, et al.
(author)
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Effects of microstructure on deformation behaviour of AZ91D cast alloy
- 2014
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In: TMS 2014 Annual Meeting Supplemental Proceedings TMS, The Minerals, Metals & Materials Society, San Diego, February 16-20, 2014. - : John Wiley & Sons. - 9781118889725 ; , s. 565-572
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Conference paper (peer-reviewed)abstract
- The deformation behavior of AZ91D cast magnesium alloy was investigated using uniaxial tensile tests from room temperature up to 190°C and strain rates from 0.0001 up to 0.1 1/s. In present work gradient solidification in a Bridgeman furnace was employed to study the effect of initial microstructure on the tensile mechanical response of the AZ91D alloy. The furnace drawing rate was varied from minimum 0.3 to maximum 6 mm/s, which yielded a variation of SDAS from 4.2 up to 25 as well as a variation of the fraction of the γ -phase (Mg17Al12),. The effects of microstructural parameters such as SDAS and γ -phase morphology on the yield strength (YS), ultimate tensile strength (UTS) and hardening were investigated
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| 4. |
- Fritzsch, R., et al.
(author)
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A novel method for automated quantification of particles in solidified aluminium
- 2014
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In: TMS 2014 143rd Annual Meeting & Exhibition, Annual Meeting Supplemental Proceedings. - Hoboken, NJ, USA : The Minerals, Metals, and Materials Society. - 9781118889725 ; , s. 535-543
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Conference paper (peer-reviewed)abstract
- Particle concentration and size distribution in the melt can give important information regarding the filtration efficiency and the quality of the aluminium. LiMCA (Liquid Metal Cleanliness Analyser) system, used in primary and secondary production of aluminium, provides in-situ data for granulometric and total density information on the inclusion content, but has problems quantifying particles < 20 μm in size. To be able to determine the required cleanliness with particle counts down' to 10 μm for modern alloys a novel method for automated quantitative results has been developed. Results are obtained using a user friendly technique based on the ImagePro® Plus 7.0 software. The different image processing steps adopted for automated quantification of the particle count in a size range from 2 to 50 μm is described and discussed together with the obtained results. The automated technique has been benchmarked elsewhere with a manual particle count reviling an error of ∼3% on the overall filtration efficiency.
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| 5. |
- Peng, Ru, et al.
(author)
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SEM Study of Fatigue Crack Growth Behavior in Duplex Stainless Steels
- 2014
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In: TMS 2014 Supplemental Proceedings. - Hoboken, NJ, USA : John Wiley & Sons. - 9781118889725 - 9781118889879 ; , s. 631-638
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Conference paper (peer-reviewed)abstract
- Mechanical properties of duplex stainless steels (DSSs) are strongly dependent on their microstructure and micromechanical behavior of the constitutive phases. The present work has investigated the growth behavior of fatigue crack in two DSSs, SAF 2507 and SAF 2906, having a different hardness ratio between the constitutive austenite and ferrite. By microstructural examination in SEM under in situ loading and also after ex situ loading, the slip activities, the development of localized cyclic plasticity and the propagation of the fatigue crack in an austenite-dominant region in the respective steel were closely followed. The growth of cracks and formation of secondary cracks were correlated to slip heterogeneities within the same grain under cyclic loading and localization of cyclic plastic strains. More profound localization of cyclic plastic strains were observed in the crack tip region in SAF 2507 than in SAF 2906, likely attributed to a softer austenite in SAF 2507.
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| 6. |
- Saleem, Saud, et al.
(author)
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Development of an asymptotics-based numerical model for the formation and evolution of air gaps in the vertical continuous casting of alloys
- 2014
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In: TMS2014 143rd Annual Meeting & Exhibition. - Hoboken, NJ, USA : John Wiley & Sons, Inc.. - 9781118889725 ; , s. 339-346
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Conference paper (peer-reviewed)abstract
- The formation of an air gap at the mould-metal interface in vertical continuous easting has long been known to have a detrimental effect on the efficiency of the process, and has therefore! attracted many attempts at mathematical modelling and multi-dimensional numerical simulation. However, a recent approach has used asymptotic techniques to derive a quasi-analytical thermomechanical model that captures the essential coupling characteristics: that the formation of the air gap affects the heat transfer, whilst the heat transfer affects the stresses that lead to the formation and evolution of the air gap. In this contribution, we report on preliminary attempts to develop that model, which was for the casting of pure metals, to describe the casting of alloys.
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