Stabilization of Laves phase by silicon in a heat-resistant steel casting and its effect on creep-rupture life

2005 ◽  
Vol 40 (8) ◽  
pp. 2085-2087 ◽  
Author(s):  
H. M. Tawancy ◽  
N. M. Abbas
Keyword(s):  
Steel Casting ◽  
Rupture Life ◽  
Creep Rupture ◽  
Laves Phase ◽  
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

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.

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.

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

scholarly journals Thermal Simulation Study on the Solidification Structure and Segregation of a Heavy Heat-Resistant Steel Casting

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 249 ◽  
Author(s):  
Biao Wang ◽  
Honggang Zhong ◽  
Xihao Li ◽  
Xiebin Wang ◽  
Tieming Wu ◽  
...  
Keyword(s):  
Steel Casting ◽  
Simulation Method ◽  
Thermal Simulation ◽  
Solidification Structure ◽  
Resistant Steel ◽  
Segregation Index ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Solidification Processes ◽  
Heavy Steel Casting

The prediction and controlling of the solidification structure and macro-segregation in heavy steel casting, which is usually produced in limited quantities, was a conundrum in the foundry field. In this work, the cooling and solidification processes of a 16 t CB2 ferritic heat-resistant steel (FHRS) valve casting were reproduced by studying the solidification behavior of three typical units through a thermal simulation method. The results indicate that the types of casting without chilling have the most uneven distribution of solutes and hardness, while those types of casting in which parts are solidified by chilling are much more uniform. The macro-segregation degrees of B, C, Nb, P, Cr, Mo, Si, V and Mn decrease gradually during heavy casting of CB2 ferritic heat-resistant steel. Of them, B, C, Nb, and P are solutes prone to segregation, and the maximum macro-segregation index of B can even reach 15. The macro-segregation tendencies of Cr, Mo, Si, V, and Mn are relatively small. Further studies on the last solidification portion of samples taken by electron microprobe reveal that large-sized precipitates such as MnS and NbxC are easily formed due to solute enrichment, and the sizes of these precipitates were distributed from dozens to hundreds of micrometers.

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