Influence of Heat Treatment in Residual Stresses Generated in P91 Steel-pipe Weld

Chuvas, Tatiane de Campos; Garcia, Pedro Soucasaux Pires; Pardal, Juan Manuel; Fonseca, Maria Cindra

doi:10.1590/1516-1439.006315

Cited by 16 publications

(8 citation statements)

References 19 publications

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“…Plastic deformation-induced stress relief during PWHT can be analytically expressed as the change in the elastic deformation limit measured in terms of material yield strength 11 . The PWHT produces stress relief due to dislocation substructure rearrangement which reduces the elastic limit of the material 12 , and according to Chuvas et al 13 , relieves the tractive and compressive residual stresses in the welded joint. Mechanical properties such as ultimate tensile strength and hardness have been reported to be reduced after post weld heat treatment process 14 .…”

Section: Introductionmentioning

confidence: 99%

“…R-VSR reduce residual stresses in structures 19 , without generating PWHT problems [7][8][9][10][11][12][13][14][15][16][17][18][19][20] , to induce one or more vibratory states in a metal structure using eccentric vibrator and its associated power and control equipment 21,22 , attached to a structure supported on rubber blocks being free to vibrate. Such systems usually work in a frequency range between 0 and 100 Hz 23 .…”

Section: Introductionmentioning

confidence: 99%

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Quantification of CTOD fracture toughness in welded joints to evaluate the efficacy of vibration stress relief compared to thermal stress relief

2020

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Resonant vibration residual stress relief (R-VSR) is an alternative method to post-weld heat treatments (PWHT) which is said to lead to less distortion and lower costs. The method of superposition of cyclic stresses and residual stresses, which can lead to localized yielding of the material, dislocation movement and subsequent stress relief. This article aims at investigating the efficiency of resonant vibration in the relief of residual stresses in welded joints of HSLA Domex700 steel sheets. Mechanical stress relief was compared to a common PWHT, and stress levels were then quantified through X-ray diffraction. Samples were also characterized by CTOD fracture toughness tests, fractographic analysis and tensile tests. Results indicate that the mechanical method was significantly less effective in relieving stresses in comparison with the PWHT, but led to apparent improvements in fracture toughness and in tensile tests. FWHM values indicated significant distortion for PWHT and less distortion for R-VSR.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantification of CTOD fracture toughness in welded joints to evaluate the efficacy of vibration stress relief compared to thermal stress relief

2020

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“…Ferritic/martensitic (F/M) steels are used in some applications of Generation ІV reactors, namely in pes, pressure vessels, etc, because there is such a high temperature in this type of reactors [5,6]. In addition, intensive research has been carried out to find a reliable and long-life material for such specific conditions.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Long and Short Term Irradiation Hardening of P91 and P92 Ferritic/Martensitic Steels

Hiwa¹,

Ari²

2019

PAST-TF

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The aim of the study was to determine the effect of proton irradiation at room temperature on ferritic/martensitic P91 and P92 steels, in particular on their hardness. In addition, SRIM programme was used to identify the proton penetration depth. The study has found that the hardness of the unirradiated P92 steel is higher than that of unirradiated P91 steel, since P92 steel contains tungsten, which produces higher level of solid solution hardening. P91 and P92 steel samples were irradiated using 1.9-MeV protons to the fluence of 1.3510 17 ion/cm 2 . It was found that Vickers hardness test values increased for both P91 and P92 steels at 0.2 kg loads. For high proton irradiation (long irradiation period) the fluence was 1.10110 18 ion/cm 2 (about ten times higher than at the low proton irradiation). With growth of irradiation fluence, the number of displacements per atom (dpa) went up from 0.043 dpa (for low irradiation) to 0.18 dpa (for high irradiation) and the hardness of steels that were under investigation increased. P91 and P92 steel samples after long irradiation were heat treated for one hour at 700 o C in a vacuum furnace. The study identified that while the chemical composition of P91 and P92 steel were almost identical, irradiated P92 steel requires twice the heat treatment to reduce its hardness to a basic value, as compared with P91 steel samples.Целью данного исследования было определение влияния облучения протонами при комнатной температуре на ферритномартенситные стали Р91 и Р92, в частности, на их твёрдость. Кроме того, для изучения глубины внедрения протонов в стали была использована вычислительная программа SRIM. Обнаружено, что необлучённая сталь Р92 твёрже, чем необлучённая сталь Р91. Сталь Р92 содержит вольфрам, который способствует упрочнению твёрдых растворов. Образцы сталей Р91 и Р92 были кратковременно облучены протонами энергией 1,9 МэВ до флюенса 1,35·10 17 ион/см 2 . Под нагрузкой 200 г их твёрдость по Виккерсу увеличилась. Затем аналогичные образцы были подвергнуты приблизительно в 10 раз более длительному облучению до флюенса 1,101·10 18 ион/см 2 . С увеличением продолжительности облучения увеличилось число смещений на атом с 0,043 до 0,18 млн -1 и увеличилась твёрдость образцов. После более длительного облучения образцы исследуемых сталей были подвергнуты термообработке -помещены на один час в вакуумную печь при температуре 700 ºС. Исследование показало, что, хотя химический состав исследованных сталей почти идентичен, термообработка облучённой стали Р92 для снижения её твёрдости до исходного уровня требует вдвое большего времени, чем термообработка образцов стали Р91.Ключевые слова: программа SRIM, сканирующий электронный микроскоп, смещение на атом, сталь Р91, сталь Р92.

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“…Although the residual stresses are considerably reduced by the heat treatment, it is essential to note that they may not be completely relieved and in some cases are merely redistributed [15][16][17]. As the primary concern for the structural integrity of pressure vessels used in nuclear power plants is creep, the portion of residual stresses retained in the component, after PWHT, may still pose a threat to structural integrity in service and contribute to creep failure.…”

Section: Introductionmentioning

confidence: 99%

Examining Stress Relaxation in a Dissimilar Metal Weld Subjected to Postweld Heat Treatment

Venkata¹,

Khayatzadeh²,

Achouri

et al. 2018

Materials Performance and Characterization

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Dissimilar metal welds are often required in nuclear power plants to join components made from austenitic steels to those from ferritic steels, particularly in fast breeder reactor plants to join the intermediate heat exchanger to the steam generator. The process of welding alters the microstructure of the base materials and also causes residual stresses to form, both due to the change in the microstructure and the differing thermal histories in various regions. Post-weld heat treatment (PWHT) is required to relieve the residual stresses and achieve preferable microstructural gradients across the weld joint. Therefore, in order to arrive at the optimal PWHT process, it is necessary to investigate the effects of heat treatment on the joint integrity, microstructure and residual stress relaxation in the welds.To investigate this effect of PWHT on the residual stress relaxation and corresponding alteration of microstructure across a welded joint, a dissimilar weld between modified 9Cr-1Mo (P91) steel and austenitic stainless steel AISI 316LN was made using autogenous electron beam (EB) welding. To achieve this, the welding process was first modelled numerically using finite element analysis and the residual stress predictions were validated with experimental investigation using neutron diffraction. The validated model was then used to study the residual stress relaxation through the simulation of PWHT. The predicted stress relaxation was compared with contour method measurement of residual stresses in the actual welded plate subjected to PWHT. The results indicate that albeit some relaxation of residual stresses during PWHT, there is still a significant portion of highly localised residual stresses left in the specimen.

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Influence of Heat Treatment in Residual Stresses Generated in P91 Steel-pipe Weld

Cited by 16 publications

References 19 publications

Quantification of CTOD fracture toughness in welded joints to evaluate the efficacy of vibration stress relief compared to thermal stress relief

Quantification of CTOD fracture toughness in welded joints to evaluate the efficacy of vibration stress relief compared to thermal stress relief

Investigation of Long and Short Term Irradiation Hardening of P91 and P92 Ferritic/Martensitic Steels

Examining Stress Relaxation in a Dissimilar Metal Weld Subjected to Postweld Heat Treatment

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