The effect of thermo-mechanical processing on grain boundary character distribution in Incoloy 800H/HT

Akhiani, Hamed; Nezakat, Majid; Sanayei, Mohsen; Szpunar, Jerzy A.

doi:10.1016/j.msea.2014.12.046

Cited by 41 publications

(13 citation statements)

References 27 publications

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“…The results showed that the thermo-mechanical process can also introduce nanoscale precipitates in the matrix. Further research on the effect of TMP on the grain boundary character distribution (GBCD) in Incoloy800H was carried out [10]. The coincidence-site lattice boundaries increased with the pre-deformation level of the samples.…”

Section: Introductionmentioning

confidence: 99%

Continuous Casting of Incoloy800H Superalloy Billet under an Alternating Electromagnetic Field

Wang

Zhang

Deng

et al. 2015

Metals

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Abstract:We experimentally investigate the influence of an alternating electromagnetic field on the surface and internal qualities of Incoloy800H superalloy billets. The electromagnetic continuous casting experiments for Incoloy800H superalloy were successfully conducted and the billets (0.1 mˆ0.1 mˆ1.2 m) were obtained. We figure out that the high frequency (20.4 kHz) electromagnetic field which is applied in the mould region can improve the surface quality of Incoloy800H superalloy billet remarkably; the depth of oscillation mark decreases from 1.2 mm (without electromagnetic field) to 0.3 mm (with electromagnetic field). The internal quality of the billet was studied using a variety of characterization techniques. The low frequency (5 Hz) electromagnetic field which is applied in the second cooling region can improve the internal quality; the region of the equiaxed grain increases from 2.45% (without electromagnetic field) to 41.45% (with electromagnetic field). Furthermore, macro-and micro-segregation are suppressed and the TiN inclusion number is decreased as well.

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Section: Introductionmentioning

confidence: 99%

Continuous Casting of Incoloy800H Superalloy Billet under an Alternating Electromagnetic Field

Wang

Zhang

Deng

et al. 2015

Metals

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“…SPs must satisfy at least two conditions: firstly, it is a CSL boundary with the Σ ≤ 29; secondly, the maximum misorientation deviation should under Brandon criterion. Both the CSL boundary with a Σ > 29 and the non-CSL boundary are referred to as random boundary [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…Appropriate thermomechanical process (TMP) on FCC metals with low to medium stacking fault energy can stimulate the formation of SPs [ 12 , 13 , 14 , 15 ]. It has been proved that SPs have significant impacts on optimizing material properties.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Unidirection/Bidirection Torsional Thermomechanical Processes on Grain Boundary Characteristics and Plasticity of Pure Nickel

Yuan

Liu

et al. 2021

Materials

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The “torsion and annealing” grain boundary modification of pure nickel wires with different diameters was carried out in this paper. The effects of torsional cycles as well as unidirectional/bidirectional torsion methods on grain boundary characteristic distribution and plasticity were investigated. The fraction of special boundaries, grain boundary characteristic distributions and grain orientations of samples with different torsion parameters were detected by electron backscatter diffraction. Hardness measurement was conducted to characterize the plasticity. Then, the relationship between micro grain boundary characteristics and macro plasticity was explored. It was found that the special boundaries, especially Σ3 boundaries, are increased after torsion and annealing and effectively broke the random boundary network. The bidirectional torsion with small torsional circulation unit was the most conducive way to improve the fraction of special boundaries. The experiments also showed that there was a good linear correlation between the fraction of special boundaries and hardness. The plasticization mechanism was that plenty of grains with Σ3 boundaries, [001] orientations and small Taylor factor were generated in the thermomechanical processes. Meanwhile, the special boundaries broke the random boundary network. Therefore, the material was able to achieve greater plastic deformation. Moreover, the mechanism of torsion and annealing on the plasticity of pure nickel was illustrated, which provides theoretical guidance for the pre-plasticization of nickel workpieces.

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“…The oil and gas industry is accompanied by the generation of a significant amount of gas emissions and high temperatures. It is well known that high-temperature service conditions affect the materials used [ 1 , 2 , 3 , 4 , 5 , 6 ]. The gas flaring system is an example of this severe condition.…”

Section: Introductionmentioning

confidence: 99%

Failure Analysis of a Flare Tip Used in Offshore Production Platform in Qatar

Mahdi

Esmaeili

2020

Materials

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An immature failure of a gas flare tip used in Qatar oil and gas offshore industry was investigated throughout this study. The design lifetime of the flare was fifteen years; however, it manifested immature failure resulting in a reduction of its lifetime to ten years. The flare is composed of different parts where the upper flare body and wind deflector showed failure while other components were still healthy. The material used for the aforementioned failed parts was Incoloy 800H, which is a highly corrosion and high-temperature resistant steel alloy. The material was rolled up and welded together with different welding joints. The root cause of failure was identified by using chemical analysis and microstructural and mechanical characterizations. For the mechanical characterization, an optical microscope (OM) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) analyses were used for the specimen extracted from the failed part in order to ensure that the material mentioned by the manufacturer demonstrated the same metallurgical properties. For the mechanical characterization, two sets of specimens were used, one close to the failure region and the other far from the failure area. The chemical analysis revealed that the material was truthfully Incoloy 800H. The mechanical examination results showed a significant reduction of mechanical properties, i.e., the ultimate tensile strength (UTS) and microhardness dropped by 44% and 41% for samples close and far from the failure regions, respectively. Careful examination of the failed parts indicated that failure mostly took place in the vicinity of the welds, in particular near the joints. Improper joint designs, as well as a number of joints being designed in tiny areas, worsened the harmful effect of the heat-affected zone (HAZ), resulting in crack nucleation in the HAZ regions. The effect of welding in a combination of harsh service conditions of flare caused further crack extension where they merged, resulting in final immature failure.

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The effect of thermo-mechanical processing on grain boundary character distribution in Incoloy 800H/HT

Cited by 41 publications

References 27 publications

Continuous Casting of Incoloy800H Superalloy Billet under an Alternating Electromagnetic Field

Continuous Casting of Incoloy800H Superalloy Billet under an Alternating Electromagnetic Field

Effects of Unidirection/Bidirection Torsional Thermomechanical Processes on Grain Boundary Characteristics and Plasticity of Pure Nickel

Failure Analysis of a Flare Tip Used in Offshore Production Platform in Qatar

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