Microstructural Study of Welded Joints in a High Temperature Martensitic-ferritic ASTM A335 P91 Steel

Zavaleta-Gutierrez, Nilthon Emerson; Alvarado, Jorge Vera; Cicco, Hernan De; Danon, A. J.

doi:10.1016/j.mspro.2015.04.178

Cited by 18 publications

(7 citation statements)

References 4 publications

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“…Finally, the dissolved elements in the HAZ would precipitate during PWHT resulting in higher hardness. Higher hardness due to coarse grains in HAZ was associated to the formation of martensite and the coarsening of precipitates [16]. On other hand, sample WBL exhibits tempered martensitic structure with finer grains in HAZ which justified the reason for obtained lower HAZ hardness in P91 steel [1].…”

Section: Haz Analysismentioning

confidence: 82%

Development of NiCrSiBC Weld Hardfacing Approach for P91 Steels Used in Steam Turbine Components

Naik

Калыанкар

2021

Soldag. insp.

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P91 steels are used as substrate material for steam turbine components like bush, valve seat internals, and engineering valves. These components have hardfacing of cobalt-based material to reduce the high temperature wear loss and to improve the surface hardness. However, delamination failure and higher heat affected zone (HAZ) hardness were identified challenges for P91 steels. Hence, this demands the development of a suitable weld hardfacing approach to resolve the said challenges. In this work, NiCrSiBC (Colmonoy 6) has been considered as a hardfacing material to replace cobalt-based Stellite 6 material due to elimination of radiation activity, lower cost, and higher coating hardness. FCAW and PTA techniques were used to deposit buffer layer (SS-309L) and hardfacing layer (NiCrSiBC) respectively. Sample WBL (with deposition of buffer layer) and sample WOBL (without deposition of buffer layer) are considered approaches to study the metallurgical characterization for each case. Higher coating hardness, lower HAZ hardness and lower Fe dilution were observed in sample WBL. Cr7C3, Cr2B, and Cr5B3 hard phases in block shape together with ϒ- nickel matrix solid solution was observed in coating region of sample WBL. Overall, sample WBL approach was considered to overcome weld hardfacing challenges for steam turbine industries.

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Section: Haz Analysismentioning

confidence: 82%

Development of NiCrSiBC Weld Hardfacing Approach for P91 Steels Used in Steam Turbine Components

Naik

Калыанкар

2021

Soldag. insp.

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“…Pandey et al find that the PWHT can lead to the lath breakup. This is because that, on the one hand, the lath martensites are formed during the cooling of the weld, and the fractional precipitates in the FGHAZ fail to be dissolved during welding, leading to the pinning of the martensite boundaries . On the other hand, when the PWHT is performed, the significant recovery of the martensite matrix in the FGHAZ occurs, and the precipitates coarsen so as to lose their ability to pin the martensite boundaries .…”

Section: Discussionmentioning

confidence: 99%

“…After the welding, the P91 weld needs the PWHT to improve its ductility by reducing its hardness, residual stress and non‐equilibrium structure . A great deal of the research effort has been directed at the understanding the effects of the PWHT on the microstructure and the service life of the P91 weld . The PWHT can lead to the coarsening of precipitate and the evolution of microstructure of the FGHAZ .…”

Section: Introductionmentioning

confidence: 99%

Effects of Multiple Post Weld Heat Treatments on Microstructure and Precipitate of Fine Grained Heat Affected Zone of P91 Weld

Wang

Zeng

et al. 2019

steel research int.

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To understand the potential impact of multiple post weld heat treatments (PWHTs) on service life of P91 weld, the multiple PWHTs are designed and carried out to explore their influences on microstructure and precipitate of fine grained heat affected zone (FGHAZ) of the P91 weld. The results show that the multiple PWHTs cause the recovery of martensite matrix (specifically, the elimination of lath-like structure and the decrease of dislocation's density) and the evolution of M 23 C 6 carbide (specifically, the coarsening of M 23 C 6 carbide and the change of its distribution). The recovery of martensite matrix and the coarsening of M 23 C 6 carbide are undesirable in terms of the creep resistance of the FGHAZ. Besides, the change trend of hardness is consistent with that of M 23 C 6 carbide density, indicating that the dispersion hardening introduced by the M 23 C 6 carbide plays a dominant role in hardening effect.

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“…P91 steel belongs to a family of 9-12% Cr ferritic creep resisting steels [1]. The steel was initially developed in the 1970s for application in steam generators of fast breeder reactors by Oak Ridge National Laboratory [2], [3].…”

Section: Introductionmentioning

confidence: 99%

Comparative Study on Hot Metal Flow Behaviour of Virgin and Rejuvenated Heat Treatment Creep Exhausted P91 Steel

Maube¹,

Obiko²,

Merwe³

et al. 2023

Preprint

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This article reports on the comparative study of the hot deformation behaviour of virgin (steel A) and rejuvenated heat treatment creep-exhausted (steel B) P91 steels. Hot uniaxial compression tests were conducted on the two steels at the deformation temperature range of 900°C-1050°C and a strain rate range of 0.01-10s-1 to 0.6 strain using Gleeble® 3500 equipment. The results showed that the flow stress largely depends on the deformation conditions. The flow stress for the two steels increased with an increase in strain rate at a given deformation temperature and vice versa. The flow stress-strain curves exhibited a dynamic recovery as the softening mechanism. The material constants determined using Arrhenius constitutive equations were: stress exponent was: steel A (5.76) and steel B (6.67), and the apparent activation energy was: steel A (473.1 kJ mol-1) and steel B (564.5 kJmol-1). From these results, steel A exhibited better workability than steel B. Statistical parameters analyses showed that the flow stress for the two steels had a good correlation between the experimental and predicted data. Pearson’s correlation coefficient (R) was: steel A (0.97) and steel B (0.98). The Average Absolute Relative Error (AARE) values were: 7.62% (steel A) and 6.54% (steel B). The study shows that the Arrhenius equations can effectively describe the flow stress behaviour of P91 steel, and this method is applicable to the industrial metalworking process.

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Microstructural Study of Welded Joints in a High Temperature Martensitic-ferritic ASTM A335 P91 Steel

Cited by 18 publications

References 4 publications

Development of NiCrSiBC Weld Hardfacing Approach for P91 Steels Used in Steam Turbine Components

Development of NiCrSiBC Weld Hardfacing Approach for P91 Steels Used in Steam Turbine Components

Effects of Multiple Post Weld Heat Treatments on Microstructure and Precipitate of Fine Grained Heat Affected Zone of P91 Weld

Comparative Study on Hot Metal Flow Behaviour of Virgin and Rejuvenated Heat Treatment Creep Exhausted P91 Steel

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