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.

650°C Long-Term Structure Stability Study on 18Cr-9Ni-3CuNbN Heat-Resistant Steel

2010 ◽  
Vol 654-656 ◽  
pp. 118-121 ◽  
Author(s):  
Hong Yao Yu ◽  
Jian Xin Dong ◽  
Xi Shan Xie
Keyword(s):  
Grain Boundaries ◽  
Aging Time ◽  
Structure Stability ◽  
Temperature Structure ◽  
Strengthening Effect ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Rich Phase ◽  
Heat Resistant

The Cu-containing austenitic heat-resistant steel 18Cr-9Ni-3CuNbN has been widely used as superheater and reheater tube material for modern ultra-super-critical (USC) power plants in the world. High temperature structure stability is considered to be an important factor for long-term service. Long-term aging at 650°C for this steel was conducted from 100 to 10,000hours. Effect of aging time on microstructure was studied by means of SEM, TEM and 3DAP (three dimensional atom probe). Micro-hardness tests were carried out after aging at 650°C for different times to be considered as a representative of strength. Experimental results show that Cu-rich phase, MX and M23C6 are major strengthening precipitates in this steel. With on increasing of aging time, fine nano-size Cu-rich phase particles precipitate in the grains and its size is in the range of several nanometers to 35nm till 10,000h at 650°C. The fraction of MX also increases with aging time and its average size is about 100nm till 10,000h. Carbide M23C6 mainly precipitates at grain boundaries and coarsens quickly. Investigation results show that the most important strengthening effect for 18Cr-9Ni-3CuNbN steel is contributed by Cu-rich phase and MX in the grains and M23C6 carbide at the grain boundaries.

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.

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

scholarly journals 3D Observation on Precipitates of a Ferritic Heat Resistant Steel after Long-term Creep

Materia Japan ◽  
2018 ◽  
Vol 57 (12) ◽  
pp. 619-619
Author(s):  
Tomoyuki Hatta ◽  
Nobuaki Sekido ◽  
Mitsuharu Yonemura ◽  
Kouichi Maruyama ◽  
Kyosuke Yoshimi
Keyword(s):  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Term Creep

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).

Effect of Long-Term Ageing at 600 °C on Microstructure of ZG1Cr10MoWVNbN Martensitic Heat-Resistant Steel

2018 ◽  
Vol 37 (6) ◽  
pp. 539-544
Author(s):  
Chengzhi Zhao ◽  
Ning Li ◽  
Yihan Zhao ◽  
Hexin Zhang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
M23c6 Carbide ◽  
Resistant Steel ◽  
Steam Turbines ◽  
Heat Resistant Steel ◽  
Property Variation ◽  
Heat Resistant ◽  
Before And After

AbstractA new kind of martensitic ZG1Cr10MoWVNbN heat-resistant steel has been attracted more attentions in recent years, which is mainly applied in ultra-supercritical steam turbines. The ageing property for ZG1Cr10MoWVNbN heat-resistant steel is very important because it often serves for long-time at high-temperature environment. Herein, a long-term ageing heat treatment was conducted on ZG1Cr10MoWVNbN steel at 600 °C heat for 17,000 hours. The microstructure evolution and property variation of the ZG1Cr10MoWVNbN steel were analysed before and after ageing, and also the effect of the precipitates on the mechanical properties was studied. The result showed that strength, the plastic index and impact power of the ZG1Cr10MoWVNbN steel were gradually decreased after long-term and high-temperature ageing at 600 °C due to the changes of martensite morphology and the coarsening of M23C6 carbide precipitation phase. Furthermore, fine precipitation of matrix MX carbide can also attribute to the change of mechanical properties at high temperature.

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 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
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