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Measurement and evaluation of strain fields in T23 steel based on digital image correlation method 被引量:1
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作者 林烈雄 徐孟嘉 +4 位作者 徐济进 陆皓 叶诚辉 余春 陈俊梅 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第9期1977-1985,共9页
Surface strain fields of the designed compact tension(CT)specimens were investigated by digital image correlation(DIC)method.An integrative computer program was developed based on DIC algorithms to characterize the st... Surface strain fields of the designed compact tension(CT)specimens were investigated by digital image correlation(DIC)method.An integrative computer program was developed based on DIC algorithms to characterize the strain fields accurately and graphically.Strain distribution of the CT specimen was predicted by finite element method(FEM).Good agreement is observed between the surface strain fields measured by DIC and predicted by FEM,which reveals that the proposed method is practical and effective to determine the strain fields of CT specimens.Moreover,strain fields of the CT specimens with various compressive loads and notch diameters were studied by DIC.The experimental results can provide effective reference to usage of CT specimens in triaxial creep test by appropriately selecting specimen and experiment parameters. 展开更多
关键词 digital image correlation strain fields t23 steel compact tension specimen finite element simulation
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Evolution of nonmetallic inclusions in 80-t 9CrMoCoB large-scale ingots during electroslag remelting process
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作者 Shengchao Duan Min Joo Lee +3 位作者 Yao Su Wangzhong Mu Dong Soo Kim Joo Hyun Park 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2024年第7期1525-1539,共15页
In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrM... In combination with theoretical calculations,experiments were conducted to investigate the evolution behavior of nonmetallic inclusions(NMIs)during the manufacture of large-scale heat-resistant steel ingots using 9CrMoCoB heat-resistant steel and CaF_(2)–CaO–Al_(2)O_(3)–SiO_(2)–B_(2)O_(3)electroslag remelting(ESR)-type slag in an 80-t industrial ESR furnace.The main types of NMI in the consumable electrode comprised pure alumina,a multiphase oxide consisting of an Al_(2)O_(3)core and liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO shell,and M_(23)C_(6)carbides with an MnS core.The Al_(2)O_(3)and MnS inclusions had higher precipitation temperatures than the M_(23)C_(6)-type carbide under equilibrium and nonequilibrium solidification processes.Therefore,inclusions can act as nucleation sites for carbide layer precipitation.The ESR process completely removed the liquid CaO–Al_(2)O_(3)–SiO_(2)–MnO oxide and MnS inclusion with a carbide shell,and only the Al_(2)O_(3)inclusions and Al_(2)O_(3)core with a carbide shell occupied the remelted ingot.The M_(23)C_(6)-type carbides in steel were determined as Cr_(23)C_(6)based on the analysis of transmission electron microscopy results.The substitution of Cr with W,Fe,or/and Mo in the Cr_(23)C_(6)lattice caused slight changes in the lattice parameter of the Cr_(23)C_(6)carbide.Therefore,Cr_(21.34)Fe_(1.66)C_(6),(Cr_(19)W_(4)C_(6),Cr_(18.4)Mo_(4.6)C_(6),and Cr_(16)Fe_(5)Mo_(2)C_(6)can match the fraction pattern of Cr_(23)C_(6)carbide.The Al_(2)O_(3)inclusions in the remelted ingot formed due to the reduction of CaO,SiO_(2),and MnO components in the liquid inclusion.The increased Al content in liquid steel or the higher supersaturation degree of Al_(2)O_(3)precipitation in the remelted ingot than that in the electrode can be attributed to the evaporation of CaF_(2)and the increase in CaO content in the ESR-type slag. 展开更多
关键词 nonmetallic inclusion heat-resistant steel electroslag remelting M_(23)C_(6) carbide MnS inclusion supersaturation degree
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Microstructure and Fracture Morphology in the Welding Zone of T91 Heat-resisting Steel Used in Power Station
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作者 YajiangLI BingZHOU +1 位作者 TaoFENG JiangweiREN 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2002年第5期427-430,共4页
Microstructure performance in the welding zone of T91 heat-resistant steel under the condition of TIG welding was researched by means of metallography, X-ray diffraction and scanning electron microscope (SEM). Experim... Microstructure performance in the welding zone of T91 heat-resistant steel under the condition of TIG welding was researched by means of metallography, X-ray diffraction and scanning electron microscope (SEM). Experimental results indicated that microstructure of T91 weld metal was austenite + a little amount of S ferrite when using TGS-9cb filler wire. Substructure inside the austenite grain was crypto-crystal lath martensite, on which some Cr23C6 blocky carbides were distributed. The maximum hardness (HRC44) in the welding zone is near the fusion zone. There existed no obvious softening zone in the heat-affected zone (HAZ). For T91 steel tube of $63 mmx5 mm, when increasing welding heat input (E) from 4.8 kJ/cm to 12 5 kJ/cm, fracture morphology in the fusion zone and the HAZ changed from dimple fracture into quasi-cleavage fracture (QC). Controlling the welding heat input of about 9.8 kJ/cm is suitable in the welding of T91 heat-resistant steel. 展开更多
关键词 t91 heat-resistant steel. Welding. Microsrructure
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Effects of Austenite Stabilization on the Onset of Martensite Transformation in T91 Steel 被引量:2
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作者 Baoqun NING Yongchang LIU +2 位作者 Qingzhi SHI Zhiming GAO Liushuan YANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2008年第2期202-206,共5页
The influences of thermal stabilization of austenitic on the onset temperature for a martensite transformation in T91 ferritic heat-resistant steel were studied by high-resolution differential dilatometer. The phase t... The influences of thermal stabilization of austenitic on the onset temperature for a martensite transformation in T91 ferritic heat-resistant steel were studied by high-resolution differential dilatometer. The phase transformation kinetic information was obtained by adopting lever rule from the recorded dilatometric curves. The results show that an inverse stabilization, featured by the damage of "the atmosphere of carbon atoms" and the increase of the starting temperature for martensite transformation takes place when the T91 ferritic steel is isothermally treated above the Ms point, and it becomes strong with increasing the holding time. While the continued temperature for martensite transformation decreases gradually when isothermally holding at a temperature below Ms point. The observed inverse stabilization behavior could be attributed to the relatively high temperature of Ms point in the explored T91 ferritic heat-resistant steel. 展开更多
关键词 t91 ferritic heat-resistant steel Austenitic thermal stabilization MARtENSItE MICROStRUCtURE
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Strengthening effect of Cu-rich phase precipitation in 18Cr9Ni3CuNbN austenitic heat-resisting steel 被引量:6
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作者 Chengyu CHI Hongyao YU +4 位作者 Jianxin DONG Xishan XIE Zhengqiang CUI Xiaofang CHEN Fusheng LIN 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2011年第2期141-147,共7页
The Cu-containing austenitic heat-resistant steel 18Cr9Ni3CuNbN, which is being used as superheater and reheater tube material for modern ultra-super-critical (USC) power plants all over the world, has been investig... The Cu-containing austenitic heat-resistant steel 18Cr9Ni3CuNbN, which is being used as superheater and reheater tube material for modern ultra-super-critical (USC) power plants all over the world, has been investigated at 650 ℃ long time aging till 10 000 h. SEM, TEM and 3DAP (three dimensional atom probe) have been used to follow microstructural changes with mechanical property variations. Experimental results show that Cu-rich phase and MX precipitate in the grains as well as M 23 C 6 precipitates at grain boundaries are the main precipitation strengthening phases in this steel. Among them Cu-rich phase is the most important strengthening phase. Homogeneous distribution of very fine nano-size Cu-rich phase has been formed at very early stage of 650 ℃ aging (less than 1 h). Cu atoms gradually concentrate to Cu-rich particles and the other elements (such as Fe, Cr, Ni etc) diffuse away from Curich particles to γ-matrix with the increasing of aging time at 650 ? C. The growth rate of Cu-rich phase at 650 ℃ long time aging is very slow and the average diameters of Cu-rich phase have been determined by TEM method. Cu-rich phase keeps in about 30 nm till 650 ℃ aging for 10 000 h. It shows that nano-size Cu-rich phase precipitation strengthening can be kept for long time aging at 650 ℃ because of its excellent stability at high temperatures. According to structure stability study and mechanical properties determination results the Cu-rich phase precipitation sequence and its strengthening mechanism model have been suggested and discussed. 展开更多
关键词 Austenitic heat-resistant steel Precipitation strengthening Cu-rich phase MX M 23 C 6
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Investigation of reheat cracking susceptibility in CGHAZ of modified T23 steel 被引量:1
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作者 Ren-yuan Zhou Shi-xian Li +2 位作者 Li-hui Zhu Guo-li Zhai Ming Song 《Journal of Iron and Steel Research International》 SCIE EI CSCD 2021年第11期1417-1425,共9页
T23 steel(2.25Cr–1Mo–1.6W–0.24V–0.05Nb,in wt.%)has been widely used as water walls in ultra-supercritical(USC)power plants.However,high reheat cracking susceptibility of T23 steel hazarded the safety of USC power ... T23 steel(2.25Cr–1Mo–1.6W–0.24V–0.05Nb,in wt.%)has been widely used as water walls in ultra-supercritical(USC)power plants.However,high reheat cracking susceptibility of T23 steel hazarded the safety of USC power plants.It is aimed to improve the reheat cracking susceptibility of T23 steel from the perspective of modifying chemical composition.Gleeble-3800 thermal simulator was used to simulate the coarse-grained heat-affected zone(CGHAZ)in T23 and modified T23 steels via thermal simulation of welding,and then evaluate the reheat cracking susceptibility in CGHAZ of T23 and modified T23 steels by the isothermal slow strain rate tensile test.The microstructure was systematically investigated by optical microscopy,scanning electron microscopy and transmission electron microscopy.The results show that the reheat cracking susceptibility of modified T23 steel is extremely improved.Compared with T23 steel,there are fewer M23C6 particles at the grain boundaries in modified T23 steel,and the degree of intergranular weakening is smaller.At the same time,not only MX in the grain interiors but also the solid-solutioned C and W in the matrix decrease in modified T23 steel,leading to the decline of intragranular strengthening.In addition,small grain size is beneficial to the improvement of the reheat cracking susceptibility of modified T23 steel.The decreased number of M23C6 at grain boundaries helps to retard the formation and propagation of reheat cracks because of decreased denuded zones. 展开更多
关键词 Reheat cracking susceptibility t23 steel Gleeble-3800 thermal simulator PRECIPItAtE Ultra-supercritical power plant
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Effect of rhenium on the microstructure and mechanical behavior of Fe–2.25Cr–1.6W–0.25V-0.1C bainitic steels 被引量:1
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作者 José Antonio Jiménez Manuel Carsí Oscar Antonio Ruano 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第12期1487-1493,共7页
A new ferritic creep resistant steel has been developed by eliminating Nb and adding 1.5 mass % Re to a ferritic steel grade T/P23 with the aim of enhancing its mechanical properties at high temperature.Cast ingots of... A new ferritic creep resistant steel has been developed by eliminating Nb and adding 1.5 mass % Re to a ferritic steel grade T/P23 with the aim of enhancing its mechanical properties at high temperature.Cast ingots of both steels, new grade and ASTM T/P 23, were hot rolled at 900℃ and then submitted to a thermal treatment consisting of solubilization at 1050℃ and tempering at 700℃. Tempered bainitic microstructures obtained contain second phases reinforcing carbide particles, mainly M_6C and M_(23)C_6 at the boundaries of both, prior austenite grains and bainitic ferrite laths, as well as MC within the grains. Mechanical properties at temperatures ranging from 540 to 600℃ were studied by strain-ratechange tests in compression at strain rates between 10^(-7) and 10^(-4)s^(-1). These tests showed high stress exponents(n ≥ 20) and activation energies(Q ≈ 400 k J/mol) for both alloys, which were associated with a dislocation movement mechanism with a strong interaction between dislocations and precipitates. On the other hand, a creep exponent of 5 was derived for the stress dependence of minimum creep rate from conventional-type creep tests at 600℃. Although this stress exponent is usually related to a dislocation climb controlled creep mechanism, remarkable microstructural degradation observed with increasing creep time makes difficult to elucidate the true deformation mechanism controlling creep. 展开更多
关键词 Creep resistant steel t/P23 thermal treatment tempered bainite High temperature mechanical properties Creep
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