To achieve high thermal efficiency, modern day thermal power plants operate at higher operating temperature and pressure which necessitates use of steels with high creep rupture strength such as ...modified 9Cr-1Mo steels. In the present study, the evolution of phases in modified 9Cr-1Mo P91 steel and their effects on microstructural stability and mechanical properties have been studied for specimens that were subjected to different thermal heat treatment conditions. The main focus has been to study the effect of heat treatment temperature ranging from 623K to 1033K (350–760°C) on P91 steel. Further, the effect of furnace cooling, water quenching, tempering at 1273K (1000°C) and austenitizing on the mechanical properties and microstructure has been studied. The techniques used for material characterization were scanning electron microscopy (SEM), optical microscopy (OM) and X-ray diffraction. For low tempering temperature, i.e. 623K (350°C), M23C6, M3C, M7C3, and MX precipitates have been observed with high yield strength (YS), tensile strength (UTS), hardness and low toughness. In the high temperature range, 923–1033K (650–760°C), fine MX, M7C3, M23C6, M2X, and M3C precipitates have been observed with low YS, UTS, hardness and high toughness. The steel tempered at 1033K (760°C) was observed to be having best combination of YS, UTS, hardness, toughness and ductility.
Mechanical properties of creep enhanced ferritic (CSEF) steels is affected by various parameters, the solutionizing temperature is one of them. The present work demonstrates the effect of ...solutionizing temperature on microstructure and mechanical properties of CSEF P91 steel. Optical metallography (OM) and Scanning electron microscopy (SEM) were carried out to study the microstructure of P91 steel in different heat treatment conditions. In order to determine the precipitates present in microstructure; X-ray analysis was performed. Moreover, the influence of solutionizing temperature on the mechanical properties (strength, hardness and impact toughness) has also been studied.
•SEM-EDS analysis of P91 steel precipitates present at grain boundary and grain interior were carried out.•For constant tempering time effect of normalizing temperature on precipitate size, particle-to particle distance, and grain size were carried out.•Effect of normalizing temperature on tensile strength, yield strength, hardness, % elongation and % reduction of area of P91 steel were studied.•For constant tempering time effect of normalizing temperature on room temperature impact toughness of P91 steel were studied. Fracture surface after impact testing were also characterized by using SEM.•Fracture surface after room temperature tensile testing were also characterized by using SEM to study the effect of normalizing temperature on fracture surface.
Seal glass plays a crucial role in solid oxide fuel cell performance and durability. In this review paper, overall composition–structure–property relations of seal glasses are discussed from bulk ...glass behavior, interfacial interaction, and sealing ability point of view. A seal glass should have a combination of desired thermal, chemical, mechanical, and electrical properties in order to seal cell components and stacks and prevent gas leakage. It must be stable for ∼40,000
h at 500–1000
°C in oxidizing and reducing atmospheres and withstand ∼10,000 thermal cycles between room temperature and cell operating temperature. A SrO–La
2O
3–Al
2O
3–SiO
2 based seal glass shows the promise to meet all the desired thermophysical properties, long-term stability, and thermal cycling resistance. In this paper, the most recent advances in the field are discussed along with this glass. Future seal glass research directions for solid oxide fuel cells are also analyzed.
Thermal barrier coatings (TBCs) have seen considerable advancement since the initial testing and development of thermal spray coating. Thermal barrier coatings are currently been utilized in various ...engineering areas which include internal combustion engines, gas turbine blades of jet engines, pyrochemical reprocessing units and many more. The development of new materials, deposition techniques is targeted at improving the life of the underlying substrate. Hence, the performance of the coating plays a vital role in improving the life of substrate. The scope for advancement in thermal barrier coatings is very high and continuous efforts are being made to produce improved and durable coatings. Thermal barrier coatings have the potential to address long term and short-term problems in gas turbine, internal combustion and power generation industry. The study of thermal barrier coating material, performance and life estimation is a critical factor that should be understood to introduce any advancement. The present review gives an overview of the thermal spraying techniques and current advancements in materials, mechanical properties, understanding the high temperature performance, residual stress in the coating, understanding the failure mechanisms and life prediction models for coatings.
Graphic Abstract
The creep tests were conducted on multi-pass shielded metal arc welded P91 steel weld joint at creep exposure temperature of 620 °C for an applied stress of 150 and 200 MPa in as-welded, and post ...weld heat treatments (PWHTs) state. The PWHTs involved the tempering at 760 °C/2 h/air cooling (referred as PWHT) and re-austenitizing at 1040 °C/60 min/air cooling + tempering at 760 °C/2 h/air cooling (refereed as PWNT). Results indicate a great influence of heat treatment conditions on the creep rupture life, fracture location and microstructure evolution of the P91 welded joint. As-welded and PWHT specimens showed the Type IV mode of failure and the fracture occurred in soft fine-grained heat affected zone/inter-critical heat affected zone (FGHAZ/IC-HAZ). In PWNT specimens, a shift in fracture location was observed from FGHAZ/ICHAZ to over tempered base zone. The degree of heterogeneity in terms of the microstructure and mechanical properties across the welded joints before the creep exposure have observed a great influence on the creep rupture life. As compared to other heat treated specimen, PWNT specimen exhibited higher creep rupture life at the lower applied stress of 150 MPa and creep exposure temperature of 620 °C due to lower degree of heterogeneity across the welded joints. However, Laves phase formation (Fe2W/Fe2Mo) was noticed in different zones (weld zone + heat affected zones) of the crept specimen for PWNT condition exposed at 620 °C for 150 MPa.
Creep strength enhanced ferritic/martensitic P91 steel is considered as a candidate material for the reactor pressure vessels and reactor internals of Very High Temperature Reactor (VHTR). ...Heterogeneous microstructure formation across the P91 weldments lead to premature Type IV cracking and makes the weldability of P91 steel a serious issue. The present research work describes the effect of normalizing and tempering (N&T) treatment on microstructure evolution in various zones of gas tungsten arc welded (GTAW) P91 pipe weldments. For N&T treatment, P91 pipe weldments were subjected to various normalizing (950–1150 °C) and tempering (730–800 °C) temperature. The effect of varying heat treatment on tensile properties and hardness of P91 pipe weldments were studied for V-groove and narrow-groove weld designs. The effect of increase in normalizing temperature (fixed tempering temperature) resulted in increase in strength and hardness, while increase in tempering temperature (fixed normalizing temperature) resulted in the decrease in strength and hardness of P91 steel weldments. The better combination of strength, ductility and microstructure were obtained for the maximum normalizing temperature of 1050 °C and tempering temperature of 760 °C.
Hundreds of variants associated with atopic dermatitis (AD) and psoriasis, 2 common inflammatory skin disorders, have previously been discovered through genome-wide association studies (GWASs). The ...majority of these variants are in noncoding regions, and their target genes remain largely unclear.
We sought to understand the effects of these noncoding variants on the development of AD and psoriasis by linking them to the genes that they regulate.
We constructed genomic 3-dimensional maps of human keratinocytes during differentiation by using targeted chromosome conformation capture (Capture Hi-C) targeting more than 20,000 promoters and 214 GWAS variants and combined these data with transcriptome and epigenomic data sets. We validated our results with reporter assays, clustered regularly interspaced short palindromic repeats activation, and examination of patient gene expression from previous studies.
We identified 118 target genes of 82 AD and psoriasis GWAS variants. Differential expression of 58 of the 118 target genes (49%) occurred in either AD or psoriatic lesions, many of which were not previously linked to any skin disease. We highlighted the genes AFG1L, CLINT1, ADO, LINC00302, and RP1-140J1.1 and provided further evidence for their potential roles in AD and psoriasis.
Our work focused on skin barrier pathology through investigation of the interaction profile of GWAS variants during keratinocyte differentiation. We have provided a catalogue of candidate genes that could modulate the risk of AD and psoriasis. Given that only 35% of the target genes are the gene nearest to the known GWAS variants, we expect that our work will contribute to the discovery of novel pathways involved in AD and psoriasis.
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Zn1-xNixO (x = 0.0, 0.03, 0.06, 0.09, 0.12, 0.15) nanoparticles were prepared by chemical synthesis route using hydroxyoxalate type precursors and thermal decomposition process. All the samples ...crystallize in hexagonal wurtzite structure. Nickel doping into the ZnO structure was confirmed by Energy Dispersive X-ray (EDX) spectroscopy, High Resolution Transmission Electron Microscopy (HRTEM) and UV-VIS spectroscopy. The absorption spectra show the increase in band gap with increasing doping parameter. Fluorescence (FL) spectra exhibits the excitonic peak at 354 nm relating to near band edge emission for undoped and nickel doped ZnO nanoparticles. The signature of ferromagnetism of the Zn0.91Ni0.09O sample has been evidenced by SQUID. Dielectric properties and magnetoelectric (ME) coupling of the samples have also been discussed.
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•Ni-doped ZnO nanopowders for tuning the physical properties as DMS materials.•The FL emission peak at 359 and 397 nm belongs to the exciton recombination.•Frustrated semiconducting behaviour of highly nickel doped ZnO materials.•Magnetic and magnetoelectric properties of nickel doped ZnO nanoparticles.
In the present study, different finite element (FE) models were prepared to investigate weld induced residual stresses in thick multi-pass butt welded joint of SA516 Gr. 70 plates. Both 3D and 2D ...full geometry models and their axisymmetric half models were taken into consideration. The competence of these FE models on the accuracy of predicting residual stress distribution across the weld cross-section was investigated by comparing it with the experimental results. Blind hole drilling technique and deep hole drilling technique were employed to evaluate the surface and through-thickness residual stress distributions, respectively. In addition, the change in volume and yield strength of weld material due to austenitic phase transformation was also incorporated in the material modeling to observe the effect of solid-state phase transformation (SSPT) on the evaluation of residual stresses. Computed residual stresses obtained from different FE models indicate that the 3D FE models procured the best accuracy compared with the experimental results. On the other hand, 2D models can save a significant amount of computational time with reasonable accuracy. Incorporation of SSPT in the 3D FE full model exhibited a better agreement of predicted results with the experimental measurements.
Graphic Abstract
In Very High Temperature Reactor (VHTR), The Nb-V modified 9Cr-1Mo (P91) creep strength enhanced ferritic (CSEF) steel is currently considered as a candidate material for reactor internals and ...reactor pressure vessels (RPVs). After the welding of P91 steel, the inhomogeneous microstructure of weldment is a serious issue because it promotes the well-known Type IV cracking in P91 weldments. The present research work is focused on how the microstructure evolve in various zone of P91 pipe weldment during the sub-critical post weld heat treatment (PWHT) and normalized and tempered (N&T) heat treatment. The effect of PWHT and N&T heat treatment are also considered on tensile properties and hardness variation of P91 weldments. To characterize the sample scanning electron microscope (SEM), X-ray diffraction (XRD) and optical micrograph was used. It was observed that the N&T heat treatment provides the homogeneous microstructure compared to PWHT. The superior mechanical properties was also measured in N&T condition compared to PWHT. Study of fracture surface morphology of tensile tested specimen in different heat treatment condition is also presented.
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