Effect of Al on the Microstructure and Mechanical Properties of HK40 Heat-Resistant Steel at High Temperature

2016 ◽  
Vol 849 ◽  
pp. 542-548
Author(s):  
Yan Zhang ◽  
Yu Fei Mei ◽  
Ning Zhou ◽  
Zheng Qin Liu ◽  
Yu Fu Sun
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
High Temperature ◽  
Solution Treatment ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Al Content ◽  
Heat Resistant ◽  
High Temperature Mechanical Properties ◽  
Transmission Electron

The high-temperature mechanical properties and microstructure of HK40 heat-resistant steel with different content of Al were investigated. The results from scanning electron microscope and transmission electron microscope showed that a large amount of spheroidal and dispersed γ′ phase were observed HK40 steel with 4.72wt.% and 7.10wt.% Al. The diameter of γ′ phase decreases from about 1.5μm to 50nm after solution treatment of 1200°C for 5h. The results of short term tensile test showed that tensile strength at 900°C decreased and the elongation was improved with increasing Al content. The oxides in the alloy with 4.72wt.% and 7.10wt.% Al were more uniform and finer than that in the alloy with and without 1.68wt.% Al.

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.

High Temperature Fatigue Behavior of 23Cr26Ni Heat Resistant Steel

2010 ◽  
Vol 452-453 ◽  
pp. 433-436
Author(s):  
Hee Woong Lee ◽  
S.I. Kwun ◽  
Woo Sang Jung
Keyword(s):  
High Temperature ◽  
Dislocation Density ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Solution Treatment ◽  
Cyclic Hardening ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
High Temperature Fatigue ◽  
Heat Resistant

The influence of the cooling condition after solution treatment on the high temperature fatigue resistance of 23Cr-26Ni heat resistant steel was investigated. Two different cooling conditions were applied to the steel after solution treatment at 1230oC for 3 hours. One specimen was water quenched immediately after the solution treatment. The other one was furnace cooled at a rate of 0.5oC/min down to 750oC after the solution treatment. Then, both specimens were aged at 750oC for 5 hours. The low cycle fatigue (LCF) test was conducted to investigate the influence of high temperature on the LCF behaviors of the heat-resistant 23Cr26Ni alloy. Under two different heat treatment conditions, the LCF test was performed at total strain amplitudes ranging from ±0.4~0.9% at room temperature (RT) and 600°C. During the test, initial cyclic hardening occurred at both experimental temperatures. This phenomenon was attributed to the increase in the dislocation density due to cyclic deformation, which resulted in the interaction between the newly created dislocations and precipitates. Cyclic softening was observed in the later stages of the LCF test at RT. The formation of precipitates and increase in the dislocation density were observed using TEM. Also, the XRD and EDS techniques were used to verify the type and composition of the precipitates.

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.

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