Effect of precipitates on the hot embrittlement of 11Cr–3Co–3W martensitic heat resistant steel for turbine high temperature stage blades in ultra-supercritical power plants

2019 ◽  
Vol 763 ◽  
pp. 138187 ◽  
Author(s):  
Junru Li ◽  
Tian He ◽  
Lianjun Cheng ◽  
Pengfei Zhang ◽  
Liwei Wang
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
High Temperature Stage

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

Study on the High Temperature Creep Behavior of 30Cr25Ni20 Heat-Resistant Steel

2019 ◽  
Vol 814 ◽  
pp. 157-162
Author(s):  
You Yang ◽  
Xiao Dong Wang ◽  
Wei Feng Tang
Keyword(s):  
High Temperature ◽  
Internal Structure ◽  
Creep Strain ◽  
High Temperature Creep ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Creep Fracture ◽  
Heat Resistant ◽  
Temperature Creep ◽  
Before And After

The high temperature creep test of heat-resisting steel 30Cr25Ni20 for automobile exhaust manifolds was carried out, and the creep strain-time curves at 650°C and 700°C in the different loads were obtained. The effects of different creep temperature and stress on creep life of materials were studied. The microstructure of the fracture after creep was observed by scanning electron microscopy. Microstructures before and after creep at different temperatures were compared by optical microscopy. The results show that the creep fracture life of heat-resistant steel decreases with the increase of stress at the same temperature. The creep fracture life decreases with the increase of temperature at the same stress, too. The fracture of heat-resistant steel shows good high temperature plasticity and a ductile fracture after creep. The fracture dimples become deeper with the increase of stress. At 650°Cand 700°C, the stress exponent is 8.6 and 6, respectively. When the sample was subjected to high temperature creep at 700°C, the precipitates increase obviously and the reticular structure became very large. At this point, the internal structure of the material is destroyed, and the matrix structure becomes unevenly distributed. The failure of the internal structure leads to the dramatic increase of the creep strain, and the failure of the internal structure will be more serious with the deformation of the sample.

High-Temperature Oxidation Behaviors of 30Cr25Ni20Si Heat-Resistant Steel in Air

2020 ◽  
Vol 861 ◽  
pp. 83-88
Author(s):  
You Yang ◽  
Xiao Dong Wang
Keyword(s):  
High Temperature ◽  
Oxide Film ◽  
High Temperature Oxidation ◽  
Film Growth ◽  
Surface Oxidation ◽  
Mass Gain ◽  
Resistant Steel ◽  
Temperature Oxidation ◽  
Heat Resistant Steel ◽  
Heat Resistant

High temperature oxidation dynamic behaviors and mechanisms for 30Cr25Ni20Si heat-resistant steel were investigated at 800, 900 and 1000°C. The oxide layers were characterized by scanning electron microscopy (SEM-EDS), X-ray diffractometer (XRD). The results showed that the oxidation rate of test alloys is increased with increasing the oxidation time. The oxidation dynamic curves at 800 and 900°C follow from liner to parabolic oxidation law. The transition point is 10 h. At 1000°C, the steel exhibits a catastrophic oxidation, and the oxidation mass gain value at 50 h is 0.77 mg/cm2. This suggests that the steel at 900°C has formed a dense protective surface oxidation film, effectively preventing the diffusion of the oxygen atoms and other corrosive gas into the alloy. Therefore, at the first stage of oxidation, chemical adsorption and reaction determine the oxide film composition and formation process. At the oxide film growth stage, oxidation is controlled by migration of ions or electrons across the oxide film. When the spinel scale forms, it acts as a compact barrier for O element and improving the oxidation resistance.

scholarly journals Properties of High Temperature Oxidation of Heat-resistant Steel with Aluminium and Copper

2019 ◽  
Vol 25 (4) ◽  
pp. 394-400
Author(s):  
Hong LI ◽  
Chengzhi ZHAO ◽  
Tao YAN ◽  
Chao DING ◽  
Hexin ZHANG ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Oxide Films ◽  
Main Element ◽  
Resistant Steel ◽  
Temperature Oxidation ◽  
Heat Resistant Steel ◽  
X Ray ◽  
Heat Resistant ◽  
Test Steel

The research is focused on a novel aluminum and copper-containing heat-resistant steel. The steel was designed by the material performance simulation software JmatPro, performed high-temperature oxidation tests at 650 °C and 700 °C atmospheric conditions, and analyzed the high-temperature oxidation processes and its mechanisms.The phase transtions and surface morphology of the oxide films were studied using X-ray diffraction (XRD), electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the equilibrium phase of the test steel is composed of γ phase and δ phase at 1050 °C and tranforms to tempered martensite and δ-Fe mixed structure after heat treatment. The preferential oxidation of Fe and Cr and the internal oxidation of Al occurred during the high temperature oxidation of the test steel. The oxide films were formed with various shape and weak bonding properties after high-temperature oxidation at 650℃. To the contrary, the oxide films more regular and evenly distributed, and has a certain protective effect after high-temperature oxidation at 700 ℃. The oxide films were divided into two layers, Fe2O3 is main element in the outer layer, the inner layer is mainly consisting the oxide of Cr. However, the addition of Cu element can promote the diffusion of Al and Si elements, which is beneficial to the formation of Al2O3 and SiO2 protective oxide films and excellent in high temperature oxidation resistance.

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.

Influences of Strain Rate and Deformation Temperature on Flow Stress and Dynamic Recrystalliazation of Heat Resistant Steel P91

2011 ◽  
Vol 217-218 ◽  
pp. 958-963
Author(s):  
Xue Qin Jin ◽  
Da Sen Bi ◽  
Jian Zhang ◽  
Xiao Lan Wang ◽  
Jian Hua Song ◽  
...  
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Strain Curve ◽  
Strain Rate Range ◽  
Thick Wall ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant

In power station big caliber thick wall seamless tube typical steel P91for example, The hot deformation behavior and heat flow stress-strain curve of the heat resistant steel P91was investigated with a compression test on Gleeble3500 simulator at a temperature range of 1050°C～1200°C and strain rate range of 10-4～5s-1. The test curve shows that P91 materials have the dynamic recrystallization and recovery behavior in high temperature and deformation. With the rise of temperature and strain rate of decreased, flow stress is lower and the dynamic recrystallization phenomenon is easier to occur. By metalloscope observed, in the high temperature and low strain rate conditions, the dynamic recrystallization area and new nucleation grain size are larger, and microstructure is more uniformly distributed.

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.

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