Effect of Nitrogen on the Mechanical Properties of Neutron-Irradiated Pure Iron

2009 ◽  
pp. 3-3-18 ◽  
Author(s):  
M. Castagna ◽  
A. Ferro ◽  
F. S. Rossi ◽  
J. Sebille
Author(s):  
Sara Bagherifard ◽  
Rasool Naderi Beni ◽  
Daniel Kajanek ◽  
Riccardo Donnini ◽  
Stefano Monti ◽  
...  

The mechanical properties of pure iron single crystals and of polycrystalline specimens of a zone-refined iron have been measured in compression over the temperature and strain rate ranges 2.2 to 293 °K and 7 x 10 -7 to 7 x 10 -3 s -1 respectively. Various yield stress parameters were determined as functions of both temperature and strain rate, and the reversible changes in flow stress produced by isothermal changes of strain rate or by changes of temperature at constant strain rate were also measured as functions of temperature, strain and strain rate. Both the temperature variation of the flow stress and the strain rate sensitivity of the flow stress were generally identical for the single crystals ( ca. 0.005/M carbon) and the polycrystalline specimens ( ca. 9/M carbon). At low temperatures, the temperature dependence of the yield stress was smaller than that of the flow stress at high strains, probably because of the effects of mechanical twinning, but once again the behaviour of single and polycrystalline specimens was very similar. Below 10 °K, both the flow stress and the extrapolated yield stress were independent of temperature. The results show that macroscopic yielding and flow at low temperatures are both governed by the same deformation mechanism, which is not very impurity sensitive, even in the very low carbon range covered by the experiments. The flow stress near 0 °K is ca. 5.8 x 10 -3 u where [i is the shear modulus. On the basis of a model for thermally activated flow, the activation volume at low temperatures (high stresses) is found to be ca. 5 b 3 . The exponent in the empirical power law for the dislocation velocity against stress relation is ca. 3 near room temperature, but becomes quite large at low temperatures. The results indicate that macroscopic deformation at low temperatures is governed by some kind of lattice frictional stress (Peierls-Nabarro force) acting on dislocations.


Author(s):  
T. Takeyama ◽  
H. Takahashi

It is considered that hydrogen atoms in iron dissolve interstitially in the matrix, segregate at some lattice defects, are absorbed at the interface of foreign atoms or inclusion, and/or precipitate as a gas phase. This precipitation of gaseous hydrogen in iron causes the formation of void, microcrack and blister, which affects the mechanical properties of the iron. Fracture due to hydrogen embrittlement may be caused by a crack initiation and growth, and propagation. It is obvious that this fracture depends on the diffusion of hydrogen atoms through the iron. However, the mechanism of hydrogen embrittlement cracking has not been fully explained.The aim of the present work was to investigate the microcrack and microvoid generated by the precipitation of hydrogen charged by cathodic method.Pure iron was cold-rolled to a sheet of 0.5mm thickness. After cutting, specimens were annealed at 700°C for one hour in a vacuum of 10-5torr. The grain size was l0̴20 μm. The specimens were charged with hydrogen by applying cathodic potentials in electrolytic cells containing O.1N-H2SO4 with the addition of 250 mg/ℓsodium arsenite to act as a recombination poison.


2010 ◽  
Vol 667-669 ◽  
pp. 791-796
Author(s):  
Gang Yang ◽  
Mu Xin Yang ◽  
Zheng Dong Liu ◽  
Chang Wang ◽  
Chong Xiang Huang

Commercial pure iron billets having diameter of 60 mm and length of 180 mm were subjected to equal channel angular pressing (ECAP) at 350 °C for 1-4 passes via route BC. Microstructural evolutions on three planes (X, Y, Z planes) were characterized by optical microscopy and transmission electron microscopy (TEM). It was found that after four passes an ultrafine microstructure could be formed on the X plane, but a band structure remained on the Z plane. Accordingly, the mechanical properties exhibited apparent dependence on the orientations. The strength in the X and Y directions was higher than that in the Z direction. The microstructural refinement and mechanical properties were discussed in terms of experimental results.


2012 ◽  
Vol 182-183 ◽  
pp. 332-335
Author(s):  
Yu Fang Yang ◽  
Jing Yao Zhang

The effect of particle size of iron on properties of pure iron sintered was studied systematically by the specimen current direct heating dynamic hot press sintering. It is found that mechanical properties of pure iron sintered decreased with the increasing particle size of iron. This is because big particle size of iron leads to big grain in microstructure of pure iron sintered.


Biomatter ◽  
2014 ◽  
Vol 6 (1) ◽  
pp. e959874 ◽  
Author(s):  
Camillus Sunday Obayi ◽  
Ranna Tolouei ◽  
Afghany Mostavan ◽  
Carlo Paternoster ◽  
Stephane Turgeon ◽  
...  

2013 ◽  
Vol 705 ◽  
pp. 21-25 ◽  
Author(s):  
Wei Ping Bao ◽  
Zhi Ping Xiong ◽  
Xue Ping Ren ◽  
Fu Ming Wang

Effect of strain rate on mechanical properties of pure iron was studied by compression experiments using Gleebe-1500D thermal simulation testing machine and Split-Hopkinson Pressure Bar, indicating that pure iron only has strain rate hardening effect. Adiabatic temperature rise tends to increase with increasing the strain rate. Work hardening effect is also analyzed. It found that there are only two work hardening regions in static stage (10-3 to 1 s-1) while there are three work hardening regions in dynamic stage (650 to 8500 s-1). It is on account of onset of twining at high strain rates.


2020 ◽  
Vol 16 (2) ◽  
pp. 66-70
Author(s):  
Karen Yu. Shakhnazarov

In the presented work on the basis of extrema on curves: efforts of resistance of draft, parameters of thin structure, metalgraphic structure depending on temperature and also numerous literary data on anomalies of physicomechanical properties of iron and staly transformation is declared at ~ 650 C. The research was conducted on samples from almost pure iron (0,008% C). An experiment (the metalgraphic research, the X-ray diffraction analysis, resistance to draft (Gleeble-3800) carried out through each 20 C.


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