Co Addition Effect on the Precipitation Behavior of Laves Phase in Fe-10Cr Ferritic Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 1745-1748
Author(s):  
Ick Soo Kim ◽  
S.M. Lee ◽  
Joo Yong Kim ◽  
Yoshimi Watanabe ◽  
Hisashi Sato ◽  
...  
Keyword(s):  
Power Plants ◽  
Nuclear Reactor ◽  
Laves Phase ◽  
Resistant Steel ◽  
Laves Phases ◽  
Ferritic Alloy ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Co Addition ◽  
Aging Stage

Ferritic heat-resistant steel comprises basic alloys of Fe-10mass%Cr-W. This study investigates how stress, the addition of Co, and tempering before aging affect the precipitation of the Laves phase of Fe-10Cr-6W ferritic heat-resistant steel, which is used in ultra-supercritical power plants and nuclear reactor materials. The study also investigates the mechanical properties of the steel. Precipitation of the Laves phase by aging increases the tensile strength, but decreases the elongation and impact strength of the alloys. Toughness of the alloys decreases greatly as very fine disk-like Laves phases appear in early aging stage. The strength and impact value of the steel decrease when the steel is tempered before aging. This is mainly due to decrease of density and increase of the particle size in the Laves phase. Since precipitation of the Laves phase increases by addition of Co; the strength increases and the elongation and impact value decrease.

A Research on Laser Cladding Co-Based Alloy to Repair Heat Resistant Steel of the Valves Used in Ultra-Super Critical Nuclear Power Plants

2021 ◽  
Vol 58 (5) ◽  
pp. 0514007-514007220
Author(s):  
刘福广 Liu Fuguang ◽  
李勇 Li Yong ◽  
杨二娟 Yang Erjuan ◽  
米紫昊 Mi Zihao ◽  
王博 Wang Bo ◽  
...  
Keyword(s):  
Laser Cladding ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant

Novel Concept of Creep Strengthening Mechanism using Grain Boundary Fe2Nb Laves Phase in Austenitic Heat Resistant Steel

2011 ◽  
Vol 1295 ◽  
Author(s):  
Imanuel Tarigan ◽  
Keiichi Kurata ◽  
Naoki Takata ◽  
Takashi Matsuo ◽  
Masao Takeyama
Keyword(s):  
Grain Boundary ◽  
Strengthening Mechanism ◽  
Local Deformation ◽  
Creep Rupture ◽  
Laves Phase ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Term Creep

ABSTRACTThe creep behavior of a new type of austenitic heat-resistant steel Fe-20Cr-30Ni-2Nb (at.%), strengthened by intermetallic Fe2Nb Laves phase, has been examined. Particular attention has been given to the role of grain boundary Laves phase in the strengthening mechanism during long-term creep. The creep resistance increases with increasing area fraction (ρ) of grain boundary Laves phase according to equation ε/ε = (1−ρ), where ε0 is the creep rate at ρ = 0. In addition, the creep rupture life is also extended with increasing ρ without ductility loss, which can yield up to 77% of elongation even at ρ = 89%. Microstructure analysis revealed local deformation and well-developed subgrains formation near the grain boundary free from precipitates, while dislocation pile-ups were observed near the grain boundary Laves phase. Thus, the grain boundary Laves phase is effective in suppressing the local deformation by preventing dislocation motion, and thereby increases the long-term creep rupture strength. This novel creep strengthening mechanism was proposed as “grain boundary precipitation strengthening mechanism” (GBPS).

Growth Kinetics of Laves Phase and Its Effect on Creep Rupture Behavior in 9Cr Heat Resistant Steel

2016 ◽  
Vol 23 (7) ◽  
pp. 685-691 ◽  
Author(s):  
Zhi-xin Xia ◽  
Chuan-yang Wang ◽  
Chen Lei ◽  
Yun-ting Lai ◽  
Yan-fen Zhao ◽  
...  
Keyword(s):  
Growth Kinetics ◽  
Creep Rupture ◽  
Laves Phase ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Kinetics Of ◽  
Rupture Behavior

scholarly journals Creep Rupture Behavior in Dissimilar Weldment between FB2 and 30Cr1Mo1V Heat-Resistant Steel

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jiankun Xiong ◽  
Jianping Yang ◽  
Haiyan Zhao ◽  
Lin Yang ◽  
Yang Guo ◽  
...  
Keyword(s):  
Subgrain Size ◽  
Fracture Initiation ◽  
Creep Rupture ◽  
Transgranular Fracture ◽  
Resistant Steel ◽  
Laves Phases ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Fracture Character ◽  
Rupture Behavior

Creep rupture behavior of dissimilar weldments between FB2 and 30Cr1Mo1V heat-resistant steel by multipass welding at 783 K (510°C) under different stresses (260 to 420 MPa) was researched. The fitted creep rupture exponent is 14.53, and the 10,000 h extrapolating strength values predicted by the power law and Larson-Miller parameter show good agreement with experimental data. The samples exhibit a ductile fracture character and fracture in the weld fusion zone, which has a highly heterogeneous microstructure and grains with different morphologies and sizes and an obvious softening. There exist a decrease in the dislocation and precipitate density and an increase in the subgrain size in the weld metal after creep. The rupture is a transgranular fracture characterized by dimples as a result of microvoid coalescence. Laves phases along with copper-rich precipitates are observed in the vicinity of fracture surface, which creates a stress concentration that can cause transgranular fracture initiation.

A Modified HR3C Austenitic Heat-Resistant Steel for Ultra-supercritical Power Plants Applications Beyond 650 °C

2017 ◽  
Vol 49 (2) ◽  
pp. 434-438 ◽  
Author(s):  
C. Z. Zhu ◽  
Y. Yuan ◽  
P. Zhang ◽  
Z. Yang ◽  
Y. L. Zhou ◽  
...  
Keyword(s):  
Power Plants ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant

scholarly journals Effect of Grain Boundary Fe2Nb Laves Phase on Creep of Austenitic Heat Resistant Steel of Fe-20Cr-30Ni-2Nb in Steam Atmosphere

2014 ◽  
Vol 100 (9) ◽  
pp. 1158-1164 ◽  
Author(s):  
Yu Misosaku ◽  
Imanuel Tarigan ◽  
Takahiro Kimura ◽  
Naoki Takata ◽  
Mitsutoshi Ueda ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Laves Phase ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant

An Investigation on Precipitation Behaviour of Cu-Rich Phase in Super304H Heat-Resistant Steel by Three Dimensional Atom Probe

2010 ◽  
Vol 654-656 ◽  
pp. 110-113
Author(s):  
Cheng Yu Chi ◽  
Jian Xin Dong ◽  
Wen Qing Liu ◽  
Xi Shan Xie
Keyword(s):  
Aging Time ◽  
Power Plants ◽  
Three Dimensional ◽  
Atom Probe ◽  
Strengthening Effect ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Rich Phase ◽  
Heat Resistant ◽  
Precipitation Behaviour

Super304H, a Cu-containing 18Cr-9Ni-3CuNbN heat-resisting steel is wildly used as an superheater/reheater tube material for ultra-super-critical (USC) power plants all over the world. It is recognized that the Cu-rich phase is an important strengthening phase for Super304H. However, the detail precipitation behaviour and its strengthening effect are still not very clear. Investigated material was taken from routine production and was aged at 650°C for different times. The precipitation of Cu-rich phase in Super304H was studied by three dimensional atom probe (3DAP) and TEM. Experimental results show that Cu-rich clusters have been formed at very early stage of 650°C aging. The Cu-rich particle images have been clearly caught just after 650°C aging for 5h. The Cu atoms gradually concentrate to Cu-rich particles and the other elements (such as Cr, Ni etc) diffuse away from Cu-rich particles to γ-matrix with the increasing of aging time. The Cu-rich particle size and its density have been determined as a function of aging time. Cu-rich particles still keep nano-size and distribute homogenously in grains even after long time (1,000h) aging, which is one of the most important reasons for keeping good strength of Super304H heat-resistant steel at high temperatures.

650°C Long-Term Structure Stability Study on 18Cr10NiNb Heat-Resistant Steel

2011 ◽  
Vol 399-401 ◽  
pp. 180-184 ◽  
Author(s):  
Hong Yao Yu ◽  
Cheng Yu Chi ◽  
Jian Xin Dong ◽  
Xi Shan Xie
Keyword(s):  
Aging Time ◽  
Power Plants ◽  
Stability Study ◽  
Structure Stability ◽  
Temperature Structure ◽  
Strengthening Effect ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant

The Nb-contained austenitic heat-resistant steel 18Cr10NiNb(TP347H) has been widely used as super-heater and re-heater tube material for modern ultra-super-critical (USC) power plants in the world. High temperature structure stability is considered to be one of the most important factors for long-term service. Long-term aging at 650 °C for this steel was conducted till 10,000 hours. Effect of aging time on microstructure was studied by means of SEM and TEM. Tensile tests were carried out after aging at 650 °C for different times. Experimental results show that MX phase and M23C6 carbides are major strengthening precipitates in this steel. With increasing of aging time, fine nano-size MX particles precipitate in grains and its size keeps about 50 nm till 10,000 h at 650 °C. Carbide M23C6 mainly precipitates at grain boundaries but coarsens quickly. Investigation results show that MX phase plays the most important strengthening effect in grains. The amount of MX phase increases with increasing of Nb and C contents. The effects of Nb and C contents on mole fractions of MX phase in 18Cr10NiNb steel have been calculated by using Thermo-Calc software.

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