scholarly journals Enhancing Heat Treatment Conditions of Joints in Grade P91 Steel: Looking for More Sustainable Solutions

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 495
Author(s):  
Vitor F. C. Sousa ◽  
Francisco J. G. Silva ◽  
António P. Pinho ◽  
António B. Pereira ◽  
Olga C. Paiva
Keyword(s):  
Heat Treatment ◽  
Environmental Sustainability ◽  
Power Plants ◽  
P91 Steel ◽  
Sustainable Solutions ◽  
New Class ◽  
Treatment Conditions ◽  
Temperature And Pressure ◽  
Time And Energy ◽  
Made In

Grade P91 is a relatively new class of steel, which has received special attention from designers because it presents extremely interesting characteristics for specific applications. This steel exhibits ideal properties for demanding applications, especially involving high temperature and pressure, being employed in facilities such as power plants and other equipment, such as heat exchangers. P91 welds usually need heat treatments, which are already parameterized in the codes. However, standardized treatments are time-consuming and harmful to the environment, as they massively consume energy. Some attempts have been made in the past to reduce the time and energy spent on these treatments. This work aims to extend this study, now presenting better solutions than those obtained previously. This work presents four new conditions for the heat treatment of joints carried out on P91 steel, with a view to reducing processing time, reducing energy consumption, and an even better balance between mechanical strength and elongation after failure. Heat treatment conditions were established in which there was a loss of about 14% in Ultimate Tensile Strength (UTS), but in which a gain of about 50% in elongation was obtained, compared to welding without any treatment, but also with 10% losses in the UTS and 30% gains in elongation when compared to the solution recommended as more correct in the codes, saving a lot of time and energy in the treatment process. Thus, these solutions may be adopted in the future with gains in terms of productivity and economic and environmental sustainability.

scholarly journals Evaluation of Welded Joints in P91 Steel under Different Heat-Treatment Conditions

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 99 ◽  
Author(s):  
Francisco José Gomes Silva ◽  
António Pedro Pinho ◽  
António Bastos Pereira ◽  
Olga Coutinho Paiva
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Power Plants ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Welding Parameters ◽  
Hardness Profile ◽  
P91 Steel ◽  
Treatment Conditions ◽  
Before And After

P91 steel has been of interest to many researchers over the past two decades. This interest is because this steel has very interesting characteristics for application in power plants, where it is common to have pipes that need to support steam at temperatures between 570 and 600 °C, and at pressures in the range of 170 to 230 bar. These working conditions are quite severe for most common steels, requiring increased high-temperature mechanical strength as well as high creep resistance. The manufacture of these pipes normally includes welding operations, which must preserve the main characteristics of this type of steel. This justifies the concern of the researchers to ensure the best welding conditions so that the preservation of the properties of these steels becomes possible. The present work intends to depict the best results obtained varying the heat-treatment conditions applied to weldments made on heat-resistant steel P91. This steel usually takes the designation SA 213 T91 (seamless tube) or SA 335 P91 (seamless pipe), according to ASME II, as well as the designation X10CrMOVNb9-1 according to EN 10216-2. The purpose of this study is to compare the behavior of pipe welding under different post-welding heat-treatment (PWHT) conditions. One of them is performed with thermal cycles (preheating, post-heating, and the post-weld heat treatment) in agreement with most construction codes and standard rules. The second one is performed without any thermal cycle before and after welding. Both welds were made by the same process, TIG (Tungsten Inert Gas, or GTAW—Gas Tungsten Arc Welding) in the horizontal position (2G according to ASME IX) and the same welding parameters. In order to evaluate the results obtained in the welds, microstructure analyses, hardness measurements, bending tests, and tensile tests at room and high temperature (600 °C) have been performed. Other tests were also carried out according to the quality procedures, such as visual, penetrant dye, and X-ray tests. Regarding the different strategies used in the heat treatments, the best results have been obtained using a strategy similar to the one currently in use and recommended by construction codes and steel manufacturers but excluding the phases’ transformation time, and it was possible to observe that the tensile strength is impaired by about 2% to 9% at room and elevated temperatures, respectively; the elongation is reduced by 39% at room temperature but keeps a good performance at elevated temperature; the hardness profile is very similar at both temperatures; the microstructure presented is compatible with the requirements; and no cracking trend has been reported. Thus, a new strategy for the welding heat treatment of grade 91 steels was drawn, saving energy and processing time.

scholarly journals Studies on some of mechanical properties of SS304L material under different heat treatment conditions

2021 ◽  
Vol 7 (4) ◽  
pp. 49-67
Author(s):  
Nhuan Hoang ◽  
Thuc Phuong Nguyen Thi ◽  
Xuan Thi Hoang ◽  
Xuan Vinh Tran ◽  
Thi Tuyen Hoang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Power Plants ◽  
Sigma Phase ◽  
Heating Temperature ◽  
Radiation Environment ◽  
Necessary Condition ◽  
Treatment Conditions

In the PWR pressure water reactor (PWR), stainless steel is used in many important parts in both primary and secondary water circuits. There are not enough necessary condition to experiment in extremly conditons of nuclear reactor, such as high temperature, high pressure in radiation environment in Vietnam. Therefore, in order to study the world's technology for evaluating metal materials, it is necessary to have basic research on SS304 stainless steel objects. This study deals with SS304L stainless steel, which is low carbon steel used in nuclear power plants. The material used in this work was stainless steel 304 with low C content (SS304L). AISI stainless steel 304L plates were cut by wire-cutting machine into standard specimens and then heat-treated under different conditions. Finally, the post-treated specimens were tested by Rockwell hardness tester, tensile strength tester, and Charpy impact tester to verify the mechanical properties. The results showed that when heating the specimens in the range of 300÷900oC, cooling in the furnace to the room temperature, the value of hardness changed insignificantly. When increasing heating temperature, the yield strength and ultimate tensile strength values of the specimens decreased while the relative elongation values were almost unchanged. It means that under tested heat treatment conditions, the higher the heating temperature is, the worse mechanical properties are. The reason for this might be the appearance of the brittle sigma phase. Heat treatment results of SS304 specimens with the normalizing conditions at 900oC also shows the possibility to remove the sigma phase in the steel composition.

Development, Microstructure and Corrosion Resistance of Al-Mg-(Si) Binary and Ternary System Samples in 5.3% NaCl Solution for Applications with Environmental Impact

2015 ◽  
Vol 1114 ◽  
pp. 239-244 ◽  
Author(s):  
Ileana Nicoleta Popescu ◽  
Maria Cristiana Enescu ◽  
Vasile Bratu ◽  
Raluca Ioana Zamfir ◽  
Elena Valentina Stoian
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Mechanical Characteristics ◽  
Structural Evolution ◽  
Tensile Tests ◽  
General Corrosion ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Optimum Heat ◽  
Made In

For ensuring fuel consumption and pollution reduction, the researches made in the past decades considerable efforts to replacing steel with aluminum alloys in manufacturing auto bodies, or in naval transportation, because the promising weight saving. The researches consisted in general corrosion (the gravimetric index and the corrosion rate, Vcorr) and tensile tests (Rm, Rp0.2 and A5) in correlation with microstructure analysis of heat treated Al-Mg-(Si) system samples alloy, in order to obtain the best corrosion resistance and high mechanical characteristics. The Al alloys in extrusion state were solution treated at 510 – 545oC for 10-60 minutes, quenched in water 30-50o C and artificial aging at 150, 180 and 210°C at different time of aging (1, respectively 3, 7 and 11 hours). After heat treatment the obtained alloys were corroded in solution of 53g NaCl + 1000 ml distilled water and boiled in these solutions for 8, 16 respectively 24 hours. The gravimetric index was determinate by mass loss measurements for all types of heat treatment conditions. After corrosion test, samples were prepared for optical microstructural analyzing and mechanical tested. We have compared the obtained results on Al-Mg and Al-Mg-Si alloys. Were established (i) the optimum heat conditions parameters for obtaining of highest values of mechanical characteristics and corrosion resistance and also (ii) was explained the structural evolution during age (precipitation) hardening for both systems.

scholarly journals PRODUCTION OF LIME WITH HIGH REACTIVITY IN A FLUIDIZED BED APPARATUS OF AN INERT MATERIAL

2018 ◽  
pp. 31-37
Author(s):  
K.P. Kostohryz ◽  
V.A. Zhaivoronok ◽  
Yu.I. Khvastukhin ◽  
S.M. Roman
Keyword(s):  
Heat Treatment ◽  
Fluidized Bed ◽  
Power Plants ◽  
Thermal Power ◽  
Combustion Products ◽  
High Reactivity ◽  
Inert Material ◽  
Treatment Regimes ◽  
Treatment Conditions ◽  
Heat Treatment Regimes

In dry desulfurization, for example, of gaseous combustion products of thermal power plants and incineration plants, calcium oxide CaO, as a product of firing of natural carbonate rocks, mainly limestones (CaCO3), is widely used. Firing technology, depending on the limestone heat treatment regimes, form a product with certain physicochemical properties: porosity, specific surface, shrinkage value, chemical activity. The influence of heat treatment conditions on the properties of the product obtained is studied. The possibility of fast low temperature heat treatment of finely dispersed limestone in a fluidized bed of an inert material to produce CaO of the required quality is shown. Research facility, technique for carrying out experiments and processing experimental data are described. As a result of the research, the degree of calcination of 80 % of fine limestone in a device with fluidized bed of inert material was achieved and the residence time of the particles in the inert layer was determined. Bibl. 10, Fig. 2, Tab. 1.

On the defects of enamel coatings

2019 ◽  
pp. 145-150
Author(s):  
T. O. Soshina ◽  
V. R. Mukhamadyarovа
Keyword(s):  
Heat Treatment ◽  
Surface Tension ◽  
Electron Microscope ◽  
Enamel Coating ◽  
Surface Defects ◽  
Linear Expansion ◽  
Corrosion Properties ◽  
Treatment Conditions ◽  
Mechanical And Corrosion Properties ◽  
Coefficient Of Linear Expansion

The defects destroy the integrity of the enamel, and the paper examines the influence of the physical-mechanical and corrosion properties of frits and heat treatment on the defectiveness of the enamel coating. The surface defects were scanned by electron microscope. It has been established that the defectiveness of enamel coatings depends on the melting index, temperature coefficient of linear expansion, surface tension of the frits, and heat treatment conditions. When burning rate of the enamel coating decreases, the fine-meshed structure of the enamel changes, and the size of the defects decreases.

scholarly journals Improving the Environmental Sustainability of Flash Geothermal Power Plants—A Case Study

2015 ◽  
Vol 7 (11) ◽  
pp. 15262-15283 ◽  
Author(s):  
Lorenzo Bruscoli ◽  
Daniele Fiaschi ◽  
Giampaolo Manfrida ◽  
Duccio Tempesti
Keyword(s):  
Environmental Sustainability ◽  
Power Plants ◽  
Geothermal Power

scholarly journals Heat Treatment Evaluation for the Camshafts Production of ADI Low Alloyed with Vanadium

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1036
Author(s):  
Eduardo Colin García ◽  
Alejandro Cruz Ramírez ◽  
Guillermo Reyes Castellanos ◽  
José Federico Chávez Alcalá ◽  
Jaime Téllez Ramírez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Ductile Iron ◽  
Volume Fraction ◽  
Energy Impact ◽  
Treatment Conditions ◽  
Mold Casting ◽  
Grade 3 ◽  
Good Agreement

Ductile iron camshafts low alloyed with 0.2 and 0.3 wt % vanadium were produced by one of the largest manufacturers of the ductile iron camshafts in México “ARBOMEX S.A de C.V” by a phenolic urethane no-bake sand mold casting method. During functioning, camshafts are subject to bending and torsional stresses, and the lobe surfaces are highly loaded. Thus, high toughness and wear resistance are essential for this component. In this work, two austempering ductile iron heat treatments were evaluated to increase the mechanical properties of tensile strength, hardness, and toughness of the ductile iron camshaft low alloyed with vanadium. The austempering process was held at 265 and 305 °C and austempering times of 30, 60, 90, and 120 min. The volume fraction of high-carbon austenite was determined for the heat treatment conditions by XRD measurements. The ausferritic matrix was determined in 90 min for both austempering temperatures, having a good agreement with the microstructural and hardness evolution as the austempering time increased. The mechanical properties of tensile strength, hardness, and toughness were evaluated from samples obtained from the camshaft and the standard Keel block. The highest mechanical properties were obtained for the austempering heat treatment of 265 °C for 90 min for the ADI containing 0.3 wt % V. The tensile and yield strength were 1200 and 1051 MPa, respectively, while the hardness and the energy impact values were of 47 HRC and 26 J; these values are in the range expected for an ADI grade 3.

Effect of copper incorporation on phase transformation behavior of electroless nickel–phosphorous coating and its effect on the tribological behavior

2020 ◽  
pp. 146442072098160
Author(s):  
Abhijit Biswas ◽  
Suman Kalyan Das ◽  
Prasanta Sahoo
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Tribological Behavior ◽  
Electroless Nickel ◽  
Two Phase ◽  
Microstructural Changes ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Higher Temperature ◽  
Effect Of Copper

The microstructural changes of electroless Ni–P–Cu coating at various heat-treatment conditions are investigated to understand its implications on the tribological behavior of the coating. Coatings are heat-treated at temperatures ranging between 200°C and 800 °C and for 1–4 h duration. Ni–P–Cu coatings exhibit two-phase transformations in the temperature range of 350–450 °C and the resulting microstructural changes are found to significantly affect their thermal stability and tribological attributes. Hardness of the coating doubles when heat-treated at 452 °C, due to the formation of harder Ni3P phase and crystalline NiCu. Better friction and wear performance are also noted upon heat treatment of the coating at the phase transformation regime, particularly at 400 °C. Wear mechanism is characterized by a mixed adhesive cum abrasive wear phenomena. Heat treatment at higher temperature (600 °C and above) and longer duration (4 h) results in grain coarsening phenomenon, which negatively influences the hardness and tribological characteristics of the coating. Besides, diffusion of iron from the ferrous substrate as well as greater oxide formation are noticed when the coating is heat-treated at higher temperatures and for longer durations (4 h).

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