Microstructure and mechanical behavior of P91 steel dissimilar welded joints made with IN718 filler

Kumar, Sanjeev; Pandey, Chandan; Goyal, Amit

doi:10.1016/j.ijpvp.2020.104290

Cited by 33 publications

(8 citation statements)

References 47 publications

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“…Similar test results are presented in [ 31 , 38 ]. According to [ 33 ], in addition to M 23 C 6 and MX particles, the Laves phase precipitates are also observed in this area.…”

Section: Resultssupporting

confidence: 79%

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Microstructure and Mechanical Properties of Modern 11%Cr Heat-Resistant Steel Weld Joints

et al. 2021

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In addition to good high-temperature creep resistance and adequate heat resistance, steels for the power industry must have, among other things, good weldability. Weldability of such steels is one of the criteria determining whether or not the material is suitable for applications in the power industry. Therefore, when materials such as martensitic steel Thor 115 (T115) are introduced into the modern power industry, the quality and properties of welded joints must be assessed. The paper presents the results of metallographic and mechanical investigations of T115 martensitic steel welded joints. The analysis was carried out on joints welded with two filler metals: WCrMo91 (No. 1) and EPRI P87 (No. 2). The scope of the investigations included: microstructural investigations carried out using optical, scanning and transmission electron microscopy and mechanical testing, i.e., Vickers microhardness and hardness measurement, static tensile test and impact test. The macro- and microstructural investigations revealed correct structure of the weld, without welding imperfections. The microstructural investigations of joint No. 1 revealed a typical structure of this type of joint, i.e., the martensitic structure with numerous precipitates, while in joint No. 2, the so-called Nernst’s layers and δ-ferrite patches were observed in the weld fusion zone as well as the heat affected zone (HAZ). The mechanical properties of the test joints met the requirements for the base material. A slight influence of the δ-ferrite patch on the strength properties of joint No. 2 was observed, and its negative effect on the impact energy of HAZ was visible.

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“…Similar test results are presented in [ 31 , 38 ]. According to [ 33 ], in addition to M 23 C 6 and MX particles, the Laves phase precipitates are also observed in this area.…”

Section: Resultssupporting

confidence: 79%

“…Their presence in the joint is caused by the existence of a stationary liquid layer in the pool, adjacent to the fusion line, during the welding [ 9 ]. Also the formation of the NF occurs mainly due to difference in the melting point of the base material and filler metal [ 38 , 40 ]. Therefore, these areas were not observed in joint No.…”

Section: Resultsmentioning

confidence: 99%

Microstructure and Mechanical Properties of Modern 11%Cr Heat-Resistant Steel Weld Joints

et al. 2021

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“…Figure 5 also presents the peak temperature experienced by each sub-zone and the corresponding optical micrographs. The microstructural evolution strongly influences the variation in mechanical properties along the sub-zones during the welding thermal cycle [58]. Zhang et al [50] had reported the lower critical temperature (A c1 ) and upper critical temperature (A c3 ) for P92 steel to be 835-845 • C and 920-930 • C, respectively.…”

Section: Weldment Characterizationmentioning

confidence: 99%

“…properties along the sub-zones during the welding thermal cycle [58]. Zhang et al [50] had reported the lower critical temperature (Ac1) and upper critical temperature (Ac3) for P92 steel to be 835-845 °C and 920-930 °C, respectively.…”

Section: Weldment Characterizationmentioning

confidence: 99%

Influence of PWHT Parameters on the Mechanical Properties and Microstructural Behavior of Multi-Pass GTAW Joints of P92 Steel

et al. 2022

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The 9% Cr steels were developed for ultra-supercritical (USC) power plants to meet the requirements of high operating temperature and pressure. These steels are produced to operate at high temperatures where impact toughness is not a concern; however, it becomes important for the welded joints to have good impact toughness at room temperature for manufacturing. The present work investigates the effect of the post-weld heat treatment (PWHT) parameters, i.e., temperature and time, on the impact toughness of multi-pass gas tungsten arc welded (GTAW) joints of ferritic/martensitic grade P92 steel. The microstructural evolution in welded joints given varying post-weld temperatures and times was studied. The lath martensitic structure of the weld metal for the as-welded joints resulted in high hardness and low impact toughness. The weld fusion zone toughness was 12 J, which was lower than the minimum specified values of 41 J (ASME standards) and 47 J (EN ISO 3580:2017). The PWHT temperature and time were found to have a significant effect on the impact toughness of the weld metal. A drastic increase in the impact toughness of the weld metal was noticed, which was attributed to lath break-up, reduction in dislocation density and reduction in solid solution hardening. The maximum impact toughness of 124 J was measured for PWHT temperature and time of 760 °C and 120 min, respectively. The effect of PWHT parameters on tensile strength was also investigated, and test results showed that the joint was safe for USC boiler application as it failed from the region of the P92 base metal. The variation in microstructural evolution along the weldments resulted in hardness variation. PWHT led to homogeneity in microstructure and, ultimately, reduction in hardness value. According to the study, the optimum temperature and time for PWHT of a GTAW joint of P92 steel were found to be 760 °C and 120 min, respectively.

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“…Moreover the dissolution of the elements in the matrix along the solidification grain boundaries (SGB) occurs while subjecting the joints to a post weld heat treatment to obtain a higher strength and ductility is recommended. [19][20][21][22] Generally the formation of FGHAZ and CGHAZ is formed during the welding of the P91/P92 steels. These CGHAZ are formed owing to the presence of precipitates along with the patches of δ ferrite, which do not have any significant effect on ageing process.…”

Section: Introductionmentioning

confidence: 99%

Microstructural and mechanical characterization of pre-used SA 335 P91 super-heater pipe weldment used in 70 MW CFBC boilers

Prabu

Sujai

Prathiba³

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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The enhanced SA 335 P91 steels are specially designed to be used in the super-heaters in thermal power plants which are commonly operated at an elevated temperature. The present study involves an analysis of microstructure and the tensile property of the used P91 tubular steel of such heat exchanger in as-received conditions. The joints were fabricated by gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) by employing ErNiCrMo-3 and E9018 B9 fillers. The microstructure showed the presence of flakes of martensite, formation of Nb-rich phases with an unmixed zone in the interface of the weld followed by the columnar and equiaxed dendrites in the centre of the weld zone, while employing the ERNiCrMo-3 filler in GTAW. Whereas in SMA welding, no such unmixed zone was observed while employing E9018 B9 filler except the precipitation of carbides. The metallurgical and mechanical characterization of welded joints was performed by optical microscope, scanning electron microscopy with energy dispersive spectroscopy (EDS), hardness, toughness and tensile tests. From the SEM/EDS analysis in the fusion zone of joints inferred the uniform distribution of the element with Nb phases and oxide formation in the pre used P91 steel for both the weldments irrespective of the fillers employed. Alongside the hardness of the SMA weld zone showed a higher hardness by the precipitation of M23C6 and martensitic structure compared to the GTAW weld zone which is found to be lower owing to the presence of elements such as Mo, Nb, Al and C. In both the joints, the tensile failure occurred away from the fusion zone in the parent metal and SMAW joints imparted better strength than GTAW joints. The GTAW joints showed better toughness by ensuring the ductile mode of failure in fractography studies.

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Microstructure and mechanical behavior of P91 steel dissimilar welded joints made with IN718 filler

Cited by 33 publications

References 47 publications

Microstructure and Mechanical Properties of Modern 11%Cr Heat-Resistant Steel Weld Joints

Microstructure and Mechanical Properties of Modern 11%Cr Heat-Resistant Steel Weld Joints

Influence of PWHT Parameters on the Mechanical Properties and Microstructural Behavior of Multi-Pass GTAW Joints of P92 Steel

Microstructural and mechanical characterization of pre-used SA 335 P91 super-heater pipe weldment used in 70 MW CFBC boilers

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