Creep Rupture of the Simulated HAZ of T92 Steel Compared to that of a T91 Steel

Peng, Yuquan; Chen, Tai-Cheng; Chung, Tien-Jung; Jeng, Sheng-Long; Huang, Ruey‐Shing; Tsay, L.W.

doi:10.3390/ma10020139

Cited by 15 publications

(9 citation statements)

References 37 publications

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“…The A C1 , A C3 , M s , and M f temperatures determined by a dilatometer in this work at heating and cooling rates of 15 • C/sec were 870, 915, 425, and 258 • C, respectively. The A C1 and A C3 temperatures of T91 and T92 steels will moderately increase with increasing the heating rates [9,20]. The in situ martensitic transformation of 201 SS under straining can be determined by synchrotron X-ray [21].…”

Section: Resultsmentioning

confidence: 99%

“…Thin foils were prepared by twin-jet polishing in an electrolyte consisting of 75% ethanol, 20% C 3 H 5 (OH) 3 , and 5% HClO 4 acid at −20 • C. Moreover, the cuboidal specimens of various microstructures were also examined with an SEM equipped with an electron backscatter diffraction (EBSD) to reveal the grain size, high-angle and subgrain boundaries of the specimens. To realize the influence of prior thermal history on the short-term creep rupture of various specimens, dog-bone samples, as shown in Figure 1b, were loaded with dead weight under different stresses and temperatures [20]. The changes in microstructures in the fracture zone of crept samples were analyzed by using EBSD, as shown in Figure 1c.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

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The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Shiue

et al. 2018

Metals

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As-received Gr.91 steel tube was normalized at either 940 or 1060 • C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 • C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system was used to simulate HAZ microstructures in the weld, which included over-tempering (OT) and partial transformation (PT) zones. The results of short-term creep tests showed that normalizing at higher temperature improved the creep resistance of the Gr.91 steel. By contrast, welding thermal cycles would shorten the creep life of the Gr.91 steel. Among the tested samples in each group, the PT samples had the shortest life to rupture, especially the 940NT-PT sample. The microstructures of the PT samples comprised of fine lath martensite and ferrite subgrains with carbides decorating the grain and subgrain boundaries. Excessive dislocation recovery, rapid coalescence of refined martensite laths, and growth of ferrite subgrains were responsible for the poorer creep resistance of the PT samples relative to those of the other samples.

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Section: Resultsmentioning

confidence: 99%

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Shiue

et al. 2018

Metals

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“…P/T92 grade (EN X10CrWMoVNb9-2) creep-resistant steel belongs to a group of modern, high-alloyed structural materials, typically used in high-efficiency power engineering [1][2][3]. It is frequently utilized for constructing the high-temperature boiler components of supercritical and ultra-supercritical power plants.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Various Conditions of Short-Term Rejuvenation Heat Treatment on Room-Temperature Mechanical Properties of Thermally Aged P92 Boiler Steel

et al. 2021

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In this work, the effects of various conditions of short-term rejuvenation heat treatment on room-temperature mechanical properties of long-term aged P92 boiler steel were investigated. Normalized and tempered P92 steel pipe was thermally exposed at 600 °C for time durations up to 5000 h in order to simulate high-temperature material degradation, as also occurring in service conditions. Thus, thermally embrittled material states of P92 steel were prepared, showing tempered martensitic microstructures with coarsened secondary phase precipitates of Cr23C6-based carbides and Fe2W-based Laves phase. Compared with the initial normalized and tempered material condition, thermally aged materials exhibited a slight decrease in strength properties (i.e., yield stress and ultimate tensile strength) and deformation properties (i.e., total elongation and reduction of area). The hardness values were almost unaffected, whereas the impact toughness values showed a steep decrease after long-term ageing. An idea for designing the rejuvenation heat treatments for restoration of impact toughness was based on tuning the material properties by short-term annealing effects at various selected temperatures somewhat above the long-term ageing temperature of P92 material. Specifically, the proposed heat treatments were performed within the temperature range between 680 °C and 740 °C, employing variable heating up and cooling down conditions. It was revealed that short-term annealing at 740 °C for 1 h with subsequent rapid cooling into water represents the most efficient rejuvenation heat treatment procedure of thermally aged P92 steel for full restoration of impact toughness up to original values of normalized and tempered material state. Microstructural observations clearly indicated partial dissolution of the Laves phase precipitates to be the crucial phenomenon that played a key role in restoring the impact toughness.

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“…After tempering at 1033 K for 2 h, the LT and HT specimens had nearly the same hardness of HV 245. Under the same normalized and tempered conditions, the hardness of the Gr.91 steel was about HV 20 lower than that of the T92 steel [29,33]. Under the simulated over-tempered condition, the LT-OT and HT-OT specimens showed minor decreases in hardness to HV 206, regardless of the prior normalizing condition.…”

Section: Resultsmentioning

confidence: 89%

“…The as-received steel tubes were normalized at either 1213 K (L) or 1333 K (H) for 1 h in high vacuum, followed by Ar-assisted cooling to room temperature and then tempering at 1033 K for 2 h. The normalized and tempered substrates were named LT or HT samples according to the normalizing temperature. The A C1 , A C3 , M s , and M f temperatures were measured by a DIL 805A/D dilatometer (TA Instruments, Hüllhorst, Germany) at heating and cooling rates of 15 K/sec [33]. The A C1 , A C3 , M s , and M f temperatures were 1159, 1207, 663, and 497 K, respectively.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Microstructural Evolution and Short-Term Creep Rupture of the Simulated HAZ in T92 Steel Normalized at Different Temperatures

Liao

Chen

et al. 2019

Metals

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T92 steel tubes have been widely applied in advanced supercritical boilers to replace Gr.91 tubes. Simulated samples with microstructures similar to those present in the heat-affected zone (HAZ) of a T92 steel weld were subjected to short-term creep tests in the study. T92 steel tubes were normalized at either 1213 K (L) or 1333 K (H) for 1 h, followed by tempering (T) at 1033 K for 2 h. After the normalizing and tempering treatments, the HT samples comprised finer precipitates but in greater numbers along the prior austenite grain boundaries (PAGBs) and martensite lath boundaries, as compared with those of the LT samples. The HAZ microstructures in the T92 steel welds were simulated by using an infrared heating system, which included over-tempering (OT, below AC1) and partial transformation (PT, slightly below AC3) zones. Martensite laths in the OT sample were more likely to be replaced by numerous cellular structures or subgrains together with spherodized carbides mainly located at the lath and austenite grain boundaries. Furthermore, coarser but fewer carbides were found along the refined lath and grain boundaries in the PT samples, in comparison with other samples in each group. Short-term creep tests showed that the PT samples were more likely to fracture than other samples in each group. Moreover, under the same testing conditions, the microstructures of T92 steel were more stable and resistant to degradation than those of T91 steel after welding or loading at elevated temperatures. Such events were responsible for higher creep resistance of the simulated T92 samples than that of the simulated T91 samples under the same creep-rupture conditions.

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Creep Rupture of the Simulated HAZ of T92 Steel Compared to that of a T91 Steel

Cited by 15 publications

References 37 publications

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

The Effects of Various Conditions of Short-Term Rejuvenation Heat Treatment on Room-Temperature Mechanical Properties of Thermally Aged P92 Boiler Steel

Microstructural Evolution and Short-Term Creep Rupture of the Simulated HAZ in T92 Steel Normalized at Different Temperatures

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