Investigation of New Stainless Steels Developed for Industrial and Nuclear Applications
Ahmed Said Mohamed Tageldin Mohamed;
Abstract
In this thesis, new grades of austenitic stainless steels were produced and studied for nuclear reactor core as well as protective materials in tough mediums. The proposed sectors are for in-core applications in advanced liquid metal fast breeder reactors (LMFBR) and for first wall and structural materials applications for commercial fusion reactors. In this respect, new generations of tungsten stainless steel alloys were produced by replacement the molybdenum by tungsten. The standard stainless steel SS316 was fabricated and studied as a reference material. Metallurgical characteristics and attenuation properties of the investigated materials were examined using several techniques.
The microstructure of the investigated stainless steel alloys has been predicted theoretically using Schaeffler diagram, which is confirmed experimentally by metallurgical microscope. A single austenite phase was observed for SSW1, SSW3, SSW4 and SSW5 stainless steels, while SSW2 and SS316 have an austenite phase with a small ferrite phase.
Vickers hardness test was measured for the studied stainless steel alloys. The developed tungsten stainless steels have higher hardness than the standard stainless steel. Among all modified stainless steels, the modified SSW4 (1.79 %W) austenitic stainless steel has the highest hardness. Ultimate tensile strength, 0.5% proof stress, and elongation to fracture were estimated throughout the tensile test. While an impact-testing machine was used to measure the energy transferred to the stainless steel samples. Three specimens were tested at room temperature and the average of them was calculated.
Yield stress and ultimate tensile show an inversely behavior compared to elongation in which the yield stress and ultimate tensile increase and elongation decreases with the same pattern as a function of W/ (W+Mo) content. On the other hand, the modified Tungsten-stainless steels still exhibit high impact energy.
The gamma-ray attenuation measurements were performed using 238.63, 338.28, 583.19, 911.2 and 2614.51 keV gamma lines emitted from 232Th radioactive source. The sodium Iodide NaI(Tl) was used to detect the transmitted gamma ray intensities under good geometry conditions. The experimental linear attenuation coefficients (μ) were measured using transmitted beam method according to the Lambert law. The experimental mass attenuation coefficients (σ_(Exp.)) were estimated and compared with the corresponding theoretical mass attenuation coeffecients (σ_(Theo.)) which were carried out using WinXCom computer program (version 3.1). The modified stainless steels have higher attenuation coefficients and lower half value layers (HVL) than the standard stainless steel. The prepared sample SSW5 is considered to be the best attenuator among all the studied alloys. The removal cross section of fast neutrons was calculated. A good agreement between both experimental and theoretical results was achieved.
The microstructure of the investigated stainless steel alloys has been predicted theoretically using Schaeffler diagram, which is confirmed experimentally by metallurgical microscope. A single austenite phase was observed for SSW1, SSW3, SSW4 and SSW5 stainless steels, while SSW2 and SS316 have an austenite phase with a small ferrite phase.
Vickers hardness test was measured for the studied stainless steel alloys. The developed tungsten stainless steels have higher hardness than the standard stainless steel. Among all modified stainless steels, the modified SSW4 (1.79 %W) austenitic stainless steel has the highest hardness. Ultimate tensile strength, 0.5% proof stress, and elongation to fracture were estimated throughout the tensile test. While an impact-testing machine was used to measure the energy transferred to the stainless steel samples. Three specimens were tested at room temperature and the average of them was calculated.
Yield stress and ultimate tensile show an inversely behavior compared to elongation in which the yield stress and ultimate tensile increase and elongation decreases with the same pattern as a function of W/ (W+Mo) content. On the other hand, the modified Tungsten-stainless steels still exhibit high impact energy.
The gamma-ray attenuation measurements were performed using 238.63, 338.28, 583.19, 911.2 and 2614.51 keV gamma lines emitted from 232Th radioactive source. The sodium Iodide NaI(Tl) was used to detect the transmitted gamma ray intensities under good geometry conditions. The experimental linear attenuation coefficients (μ) were measured using transmitted beam method according to the Lambert law. The experimental mass attenuation coefficients (σ_(Exp.)) were estimated and compared with the corresponding theoretical mass attenuation coeffecients (σ_(Theo.)) which were carried out using WinXCom computer program (version 3.1). The modified stainless steels have higher attenuation coefficients and lower half value layers (HVL) than the standard stainless steel. The prepared sample SSW5 is considered to be the best attenuator among all the studied alloys. The removal cross section of fast neutrons was calculated. A good agreement between both experimental and theoretical results was achieved.
Other data
| Title | Investigation of New Stainless Steels Developed for Industrial and Nuclear Applications | Other Titles | دراسة نوع جديد من الصلب مناسب للصناعة والتطبيقات النووية | Authors | Ahmed Said Mohamed Tageldin Mohamed | Issue Date | 2017 |
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