Delta ferrite in the weld metal of reduced activation ferritic martensitic steel

Sam, Shiju; Das, C. R.; Ramasubbu, V.; Albert, Shaju K.; Bhaduri, A.K.; Jayakumar, T.; Kumar, E. Rajendra

doi:10.1016/j.jnucmat.2014.07.008

Cited by 69 publications

(22 citation statements)

References 11 publications

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“…Similarly, TrMF is found in both error rate and experiment numbers. Phase transformation occurs in the welded zone from alpha ferrite to martensite [24]. In the solidification process, normally, stainless-steel materials losses their original strength in the weld zone because of the grain structure.…”

Section: Hardnessmentioning

confidence: 99%

Prediction of weldment mechanical properties in GMAW with robot-assisted using fuzzy logic systems

Devendran¹,

Varthanan²

2021

Mater. Res. Express

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Welding operation decides the quality of product standards in all metal work products like automobiles, aerospace vehicles, and many more. The quality of the welding process is more reliable by automating the process with robots. In this research work, the GMAW operation is automated with the “Fanuc Robot Arc mate 100iC/12” robot. The material characteristics such as ultimate tensile strength, hardness, and impact strength of weldments are predicted using a fuzzy system using triangular membership function (TrMF) and trapezoidal membership function (TMF). The simulated results are validated by comparing with experimental work, the experiments are designed using orthogonal array L18, and material characteristics are studied using fractography test. The fuzzy system is trained with experimental results using the IF-Then rule base with the help of the L18 orthogonal array. The inference system has predicted the accuracy rate of weldment mechanical properties, showing a lower error rate.

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Section: Hardnessmentioning

confidence: 99%

Prediction of weldment mechanical properties in GMAW with robot-assisted using fuzzy logic systems

Devendran¹,

Varthanan²

2021

Mater. Res. Express

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“…The outer region of the heat-affected zone is characterized by a slight drop of hardness (398 HV1), which might be due to the formation of delta ferrite. Delta ferrite can be formed during the welding process and is mainly situated at the weld metal interface due to the epitaxial growth during the start of the solidification process [15,16]. However, the hardness measurement of the FW cross-section shows a more even hardness distribution over the whole weld seam.…”

Section: Hardness Measurementsmentioning

confidence: 99%

Influence of the focus wobbling technique on the integrity and the properties of electron beam welded MarBN steel

et al. 2019

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Martensitic 9-12% chromium steel is a favored material group for critical components in thermal power plants. However, during welding of these steels, a fine-grained zone is formed within the heat-affected zone, which is subject to type IV cracking during creep exposure. Due to the MarBN alloying concept, which is characterized by the controlled addition of boron and nitrogen, the formation of the fine-grained heat-affected zone can be suppressed and the minimum creep rate can be significantly decreased. First, EB welding studies were carried out, and the influence of the process parameters on the weld seam quality, geometry, microstructure, and hardness was investigated. However, independent of the used parameters, microfissures were detected within the fusion zone of the welds. To reduce the hot crack formation within the fusion zone, focus wobbling was used. Results showed an improvement with respect to accumulated number and length of the microfissures, but the formation could not completely be prevented. Despite this problem, the mechanical properties of joint welds were determined and creep investigations were conducted. Results showed that the existence of microfissures within the fusion zone has no major influence on the mechanical and the creep properties.

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“…All three hardness distributions have in common a high hardness in the weld metal and a slight hardness drop in the transition zone between HAZ and fusion zone, which might be due to the formation of delta ferrite. The formation of delta ferrite during the welding process is mainly situated at the weld metal interface because of the epitaxial growth during the start of the solidification process [20,21]. The high hardness within the fusion zone, compared to the base material, is due to the small grain size and the freshly formed martensite which is typical for electron beamwelded martensitic steels [22].…”

Section: Hardness Distributionmentioning

confidence: 99%

Improving the integrity and the microstructural features of electron beam welds of a creep-resistant martensitic steel by local (de-)alloying

et al. 2018

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Martensitic 9-12% chromium steels present the most preferred material group for high-temperature components in thermal power plants. Previous investigations revealed that due to the use of a creep-resistant martensitic steel strengthened with boron and nitrogen (MarBN), the minimum creep rate can significantly be decreased. Furthermore, the formation of the fine-grained heataffected zone (FGHAZ) due to welding can be suppressed. This FGHAZ is subject to the most dominant failure mode (type IV cracking) of welded joints during creep exposure. By using electron beam welding, the total width of the heat-affected zone (HAZ) can be reduced compared to conventional arc welding processes. Preceding investigation on electron beam welding of MarBN steel showed recurring difficulties with hot cracking within the fusion zone. Various approaches were tried to produce defect-free welds without the use of any filler metal, but no satisfactory results were achieved. In this investigation, the chemical composition of the fusion zone was modified by the addition of conventional 9% chromium creep-resistant steel as a filler material. By using the filler material, the fusion zone was locally (de-)alloyed and defect-free joints of MarBN steel were produced.

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Delta ferrite in the weld metal of reduced activation ferritic martensitic steel

Cited by 69 publications

References 11 publications

Prediction of weldment mechanical properties in GMAW with robot-assisted using fuzzy logic systems

Prediction of weldment mechanical properties in GMAW with robot-assisted using fuzzy logic systems

Influence of the focus wobbling technique on the integrity and the properties of electron beam welded MarBN steel

Improving the integrity and the microstructural features of electron beam welds of a creep-resistant martensitic steel by local (de-)alloying

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