Change of Mechanical Properties of FM Steels after Thermal Aging

2007 ◽  
Vol 124-126 ◽  
pp. 1413-1416
Author(s):  
Sung Ho Kim ◽  
Chang Hee Han ◽  
Woo Seog Ryu
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Nuclear Power ◽  
Rupture Strength ◽  
Early Stage ◽  
Martensitic Steels ◽  
Creep Rupture Strength ◽  
Absorbed Energy ◽  
Service Behavior ◽  
The Impact

The effects of thermal aging on microstructural evolution and mechanical properties are important in the understanding of the in-service behavior of ferritic/martensitic steels in advanced nuclear power system. Ferritic/martensitic steels have been aged at 600oC for times up to 20,000 hrs. The change of mechanical properties has been examined for these aged materials. The strength and hardness was hardly changed after the thermal aging at 600oC for 20,000 hrs in all specimens. The impact absorbed energy decreased with the aging time. But the decrease of the impact absorbed energy was larger at the early stage of aging in tungsten added steels. This is attributed to the formation of Laves phase. Nitrogen which is known to increase the creep rupture strength had no effect on the degradation of the microstructure and mechanical properties during thermal aging.

Thermal Aging of Primary Circuit Piping Materials in PWR Nuclear Power Plant

2009 ◽  
Vol 1215 ◽  
Author(s):  
Xitao Wang ◽  
Shilei Li ◽  
Shuxiao Li ◽  
Fei Xue ◽  
Guogang Shu
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Thermal Aging ◽  
Nuclear Power ◽  
Early Stage ◽  
Accelerated Aging ◽  
Austenitic Stainless Steels ◽  
Fracture Morphology ◽  
Primary Circuit ◽  
The Impact

AbstractThe reserved cast austenitic stainless steels (CASS) for primary circuit piping in Daya Bay Nuclear Power Plant were studied. The changes of microstructure, mechanical properties and fracture behavior were investigated using SEM, EPMA, TEM and nanoindentation after accelerated aging at 400°C for up to 10000 h. Microhardness of ferrite increased rapidly in the early stage and then increased slowly later. The impact energy of materials declined with the aging time and reduced to a very low level after aging for 10000 hours. Fracture morphology displayed a mixture of cleavage in ferrite along with dimple and tearing in austenite. Two kinds of precipitations were observed in ferrite by TEM after long periods of aging. The fine Cr-enriched α′ phases precipitated homogeneously in ferrite, and a few larger G phases were observed as well. The precipitation of α′ phases was considered to be the primary mechanism of thermal aging embrittlement in CASS.

Effect of Model Pollutants on the Recycling of PE/PS Plastic Blends

2003 ◽  
Vol 19 (2) ◽  
pp. 61-76 ◽  
Author(s):  
Tasnim Kallel ◽  
Valérie Massardier-Nageotte ◽  
Mohamed Jaziri ◽  
Jean-François Gérard ◽  
Boubaker Elleuch
Keyword(s):  
Mechanical Properties ◽  
Ethylene Glycol ◽  
Molar Mass ◽  
Polar Molecule ◽  
Dispersed Phase ◽  
Automotive Applications ◽  
Absorbed Energy ◽  
Third Phase ◽  
The Impact ◽  
Good Agreement

PE/PS blends have been extensively studied with the objective of improving their recycling. The objective of the present study was to investigate the effect of potential pollutants on properties of high density polyethylene (HDPE)/polystyrene (PS) plastic blends. The pollutants selected were a polar molecule of low molar mass, i.e. ethylene glycol, and an oil for engine which can be considered as less polar higher molar mass molecules. Such study can be considered for the recycling of polymer wastes from automotive applications. The compatibilizer used for PE/PS blends was a non-grafted Styrene-Ethylene Butene-Styrene copolymer (SEBS). Rheological properties, morphology and mechanical properties were analyzed. Study of the morphologies and of the mechanical properties shows that a small polar molecule such as ethylene glycol can form a third phase whereas an oil can improve compatibilization (lower diameter of the dispersed phase, better adhesion). Morphologies are in good agreement with mechanical behavior. For PE/PS blends, the lower adhesion due to the presence of ethylene glycol induced a decrease of the viscosity and absorbed energy. On the opposite, the presence of oil decreases the diameter of the dispersed phase, which leads to a significant improvement of the impact properties.

Effect of Tempering Time on Microstructure and Mechanical Properties of SA738 Gr.B Steel

2021 ◽  
Vol 1016 ◽  
pp. 1739-1746
Author(s):  
Yan Mei Li ◽  
Shu Zhan Zhang ◽  
Zai Wei Jiang ◽  
Sheng Yu ◽  
Qi Bin Ye ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Yield Strength ◽  
Microstructure Evolution ◽  
Impact Energy ◽  
Nuclear Power ◽  
Microstructure And Mechanical Properties ◽  
The Impact ◽  
Tempering Time

The effect of tempering time on the microstructure and mechanical properties of SA738 Gr.B nuclear power steel was studied using SEM, TEM and thermodynamic software, and its precipitation and microstructure evolution during tempering were clarified. The results showed that SA738 Gr.B nuclear power steel has better comprehensive mechanical properties after tempering at 650 °C for 1h. With the extension of the tempering time, M3C transformed into M23C6 with increasing size, which affected the yield strength and impact energy. When the tempering time is 8h ~ 10h, due to the transformation of M3C to M23C6, the composition of matrix around the carbide changed, causing the temperature of Ac1 dropped, forming twin-martensite which deteriorated the impact toughness of the steel.

scholarly journals Influence of Mo Additions on the Mechanical Properties of Cast Duplex Stainless Steels before and after Thermal Aging

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 295
Author(s):  
Shilei Li ◽  
Yanli Wang ◽  
Xitao Wang
Keyword(s):  
Mechanical Properties ◽  
Stainless Steels ◽  
Thermal Aging ◽  
Decomposition Kinetics ◽  
Before And After ◽  
Mo Content ◽  
Impact Energies ◽  
The Impact ◽  
Hardness Values ◽  
Mo Additions

The influence of Mo additions on the mechanical properties of cast duplex stainless steel (CDSS) before and after thermal aging was investigated using a series of model alloys with different Mo contents ranging from 0 to 1.75 wt%. By increasing Mo content, the content, morphology, and distribution of ferrite in CDSS change significantly. After thermal aging at 400 °C for 3000 h, the impact properties of all CDSS specimens obviously decline, and their hardness values in ferrite significantly increase. The impact energies of the aged CDSS decline, and the proportion of cleavage features significantly increases with Mo content increasing. The spinodal decomposition kinetics in ferrite is not significantly affected by the Mo contents. High content and interconnected ferrite will lead to the severe embrittlement in CDSS after thermal aging.

Thermal Ageing Embrittlement of Casting Duplex Stainless Steels for Nuclear Power Plant

2010 ◽  
Author(s):  
Yuhong Yao ◽  
Jianfeng Wei ◽  
Jiangnan Liu ◽  
Zhengpin Wang ◽  
Yu Wang
Keyword(s):  
Stainless Steels ◽  
Thermal Aging ◽  
Nuclear Power ◽  
Power Plants ◽  
Ageing Time ◽  
Thermal Ageing ◽  
Duplex Stainless Steels ◽  
Impact Properties ◽  
Α Phase ◽  
The Impact

Cast duplex stainless steels (CSS) used for PWR pipes are degraded due to thermal ageing embrittlement during long-term service at 288 °C to 327 °C. Z3CN20-09M Cast duplex Stainless Steels (CSS) made in France for domestic nuclear power plants were thermally aged at 400 °C for 100 h, 300 h, 1000 h, 3000 h and 10000 h. The tensile properties and the impact properties at different thermal aging duration were measured and the effects of the thermal aging time on the microscopic structures and substructures of Z3CN20-09M were respectively investigated by optical microscopy and transmission electron microscopy. The results showed that the tensile strengths of Z3CN20-09M CSS increased gradually with the increment of the thermal ageing time, whereas the impact properties decreased with the prolonging of the thermal ageing time. After long thermal ageing time the dislocation configurations were greatly changed in austenite, and there were precipitates along the austenite-ferrite interface. Moreover, the iron-rich α phase and the chromium-rich α phase precipitated in ferrite aged for 10000h by nucleation and growth rather than the spinodal decomposition. All of above revealed that Z3CN20-09M CSS became brittle during thermal ageing.

Effect of Nitrogen on the Mechanical Properties of Heat-Resisting Steel

2012 ◽  
Vol 535-537 ◽  
pp. 571-575
Author(s):  
Xiao Liu ◽  
Long Mei Wang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Room Temperature ◽  
Rupture Strength ◽  
N Addition ◽  
Creep Rupture Strength ◽  
Test Steel ◽  
Scanning Electron

In this paper, the effect of N addition on mechanical properties of 21Cr-11Ni austenitic heat-resisting stainless steel was investigated. Scanning electron microscopy was used to study the fracture surfaces in the steels. N in 21Cr–11Ni heat-resisting steel can play a role of stabling austenite and ensuring the structure and mechanical properties in high temperatures. Fracture is changed from cleavage to ductile fracture to 21Cr–11Ni heat-resisting steel, and the strength of test steel are improved at room temperature by adding N, the tensile strength is increased by 8.33%. And the creep rupture strength is improved. The fracture time of the steel containing 0.2% N is 3.2 times higher than the steel containing 0.14% N at 1144K.

Mechanical Properties of Ferritic Martenstic Steels: A Review

2019 ◽  
Vol 17 (16) ◽  
pp. 18-27
Author(s):  
Hiwa Mohammad Qadr ◽  
Ari Maghdid Hamad
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Liquid Metal ◽  
Nuclear Power ◽  
Review Article ◽  
Martensitic Steels ◽  
P92 Steel ◽  
Operational Conditions ◽  
Martensitic Materials ◽  
Design Challenges

Abstract The word-wide demand for energy is constantly increasing, and therefore ideas around future energy-generation are also on the increase with the aim of meeting this demand. This includes designs for the next generation of nuclear power reactors, such as gas-cooled, liquid-metal-cooled and water-cooled reactors; the goal being to create smarter ways to produce more economical, environmentally-friendly energy. The conditions such reactors would need to meet, present significant design challenges for scientist and engineers, not least around the structural materials and components to use. Depending on the operational conditions, use of elevated- temperature ferritic/martensitic materials such as P91 and P92 steel are favoured by several of the designs for use with out-of-core and in-core applications. The main goal behind this review article is to explain mechanical properties of P91 and P92 steel; these are two types of ferritic/martensitic steels. This reviewer, highlight and discuss the development of ferritic/martenisitc steels for nuclear programmes and to explain the effect of irradiation on mechanical properties of P91 and P92.

scholarly journals Sub-surface mechanical properties and sub-surface creep behavior of wood-plastic composites reinforced by organoclay

2019 ◽  
Vol 26 (1) ◽  
pp. 114-121
Author(s):  
Sumit Manohar Yadav ◽  
Kamal Bin Yusoh
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Creep Behavior ◽  
Creep Resistance ◽  
Early Stage ◽  
Viscoelastic Model ◽  
Wood Plastic Composites ◽  
Plastic Composites ◽  
Surface Creep ◽  
The Impact

AbstractWood-plastic composites (WPC) were manufactured from polypropylene, wood flour, maleic anhydride grafted polypropylene and organoclay. The sub-surface mechanical properties and the sub-surface creep behavior of the organoclay-based WPC were examined by the nanoindentation technique. The results showed that the hardness, elastic modulus and creep resistance of the WPC enhanced with the loading of C20 organoclay. This enhancement was subject to the organoclay content and the dispersion of organoclay in the polymer matrix. The hardness, elastic modulus and creep resistance of WPC with 1 wt% organoclay content enhanced by approximately 36%, 41% and 17%, respectively, in contrast with WPC without organoclay. To study the impact of organoclay content on the creep performance of WPC, a viscoelastic model was actualized. The results demonstrated that the model was in good agreement with the experimental information. Reinforcement of organoclay prompts expansion in elastic deformation and instigates a higher initial displacement at the early stage of creep.

Effect of Thermal Aging on Microstructural Evolution in Ferrite of Duplex Stainless Steel in Nuclear Power Plant Applications

2017 ◽  
Vol 898 ◽  
pp. 818-825
Author(s):  
B. Zhang ◽  
F. Xue ◽  
S.L. Li ◽  
Xi Tao Wang ◽  
N.N. Liang ◽  
...  
Keyword(s):  
Aging Time ◽  
Thermal Aging ◽  
Atom Probe Tomography ◽  
Nuclear Power ◽  
Impact Test ◽  
Atom Probe ◽  
Nanoindentation Test ◽  
Α Phase ◽  
The Impact ◽  
Duplex Steels

Z3CN20-09M duplex steels are thermally aged at 400oC for up to 20,000 h. The mechanical properties have been characterized by Charpy V-notch impact test and nanoindentation test. It is found that the nanohardness in ferrite increases and the impact toughness decreases with aging time. Moreover, the distribution of alloying elements has been carefully characterized using atom probe tomography (APT). The results indicate that the ferrite decomposes into Cr-rich α' and Cr-lean α phase during the thermal aging and Ni-rich G-phase forms in ferrite. The effect of aging time on solute nanostructure has been investigated systematically.

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