The Measurement of Ferrite Number (FN) in Real Weldments — Final Report

Farrar, J

doi:10.1007/bf03263405

Cited by 13 publications

(8 citation statements)

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“…In a recent project [11], the steps toward developing a database for a software predicting microstructure of duplex stainless steels welds were introduced and it was mentioned that the most important output of the software is ferrite content (fraction and number). Due to the critical importance of ferrite content for the properties, different direct and indirect approaches have been proposed to measure ferrite fraction and number [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…The magnetic measurement using FERITSCOPE® is more practical, as it can rapidly provide reliable results, and different research papers, standards, and IIW documents developed a methodology to measure the ferrite fraction using this technique [14,19]. However, the risk of a large scatter in results (up to 20% in real weld metal) and the need for calibration are drawbacks [12].…”

Section: Introductionmentioning

confidence: 99%

“…Kotecki [14] showed that the ferrite number of a 100% ferritic microstructure is reduced with decreasing iron content of the alloy, which implies that the ferrite number is specific for each alloy. In addition, the final surface quality can affect the ferrite number up to 12% [12], which makes the correlation of ferrite number and ferrite fraction more complicated particularly for welds.…”

Section: Introductionmentioning

confidence: 99%

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Ferrite content measurement in super duplex stainless steel welds

et al. 2018

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Approaches to determining ferrite fraction (%) and ferrite number (FN) were examined for super duplex stainless steel (SDSS) welds. A reference sample was produced by bead-on-plate gas-tungsten arc welding of a type-2507 SDSS plate. By comparing different etchants and measurement practices, it was realized that etching with modified Beraha followed by computerized image analysis (IA) was the most accurate and quickest technique to measure ferrite fraction, which determined the same ferrite fraction (68.0 ± 2.6%) as that measured by electron diffraction backscattered analysis (67.6 ± 2.3%). A Round Robin test was performed on a reference sample at University West, Swerea KIMAB, Outokumpu Stainless, and Sandvik Materials Technology to investigate the repeatability of the technique. The ferrite fraction measurements performed at different laboratories showed very small variations, which were in the range of those seen when changing microscope in the same laboratory. After verification of the technique, the relationship between ferrite fraction and ferrite number (measured with FERITSCOPE®) was determined using 14 single (root) pass welds, including butt, corner, and TV V-, and double V-joint geometries. The best-fit equation found in this study was ferrite number (FN) = 1.1 × ferrite fraction (%). To conclude, the ferrite fraction technique suggested in the present paper was accurate and repeatable, which made it possible to determine a ferrite fraction-ferrite number formula for SDSS singlepass welds.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ferrite content measurement in super duplex stainless steel welds

et al. 2018

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“…Dicha variación se pone en evidencia al observar la Tabla 1, para los rangos de composición química de los metales de soldadura correspondientes a distintos lotes de fabricación de cada una de las clasificaciones de electrodos inoxidables austenìticos utilizados. No obstante, las diferencias evidenciadas podrían ser más importantes en el control de ferrita  aplicado a componentes y elementos estructurales industriales [15], donde aparecen en forma más significativa variables tales como: aporte térmico, espesor, composición química, dilución, entre otros.…”

Section: Discussionunclassified

Análisis comparativo en la determinación de ferrita delta para aceros inoxidables austeníticos

2018

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RESUMENEn la soldadura de aceros inoxidables austeníticos la determinación de ferrita delta (ferrita-) resulta muy importante para poder conocer la susceptibilidad que presenta el metal de soldadura a la fisuración en caliente, uno de los problemas más importantes en relación con la soldabilidad, el comportamiento metalúrgico y mecánico de este tipo de aceros. La determinación de ferrita- en el metal de soldadura puede realizarse con métodos predictivos a partir de la composición química del metal aportado por el consumible de soldadura (Diagramas de Schaeffler, DeLong, WRC 1988 y WRC 1992) en forma metalográfica y a través de una técnica de ensayo no destructiva utilizando un medidor magnético para la determinación de ferrita. En este trabajo se presenta un análisis comparativo entre la determinación predictiva de ferrita- y el método magnético utilizando electrodos inoxidables austeníticos para proceso SMAW de diferentes composiciones y diámetros. Los aportes utilizados corresponden a distintos lotes de fabricación de dichos consumibles y se ha utilizado una metodología estandarizada para la determinación magnética. La correlación entre ambos métodos parece funcionar mejor para valores de NF entre 4 y 8. Los errores y la correlación entre los dos métodos aplicados para determinar NF no resultan aceptables cuando los electrodos depositan metales de soldadura con valores altos de NF, mayor que 18. Palabras clave: ferrita-, aceros inoxidables, diagramas WRC (FN), diagrama de Schaeffler. ABSTRACTIn the welding of austenitic stainless steels, the determination of delta ferrite (-ferrite) is very important to assess the susceptibility of weld metal to hot cracking, one of the major problems related to weldability, metallurgical and mechanical behavior of this type of steels. The determining  -ferrite in the weld metal can be performed with predictive methods from the chemical composition of weld metal provided by the welding consumable (the diagram of Schaeffler, Delong, WRC 1988, WRC1992), by metallography and using nondestructive testing technique by magnetic determination of ferrite. This paper presents a comparative analysis of the predictive determination of -ferrite and the magnetic method using austenitic stainless electrodes for SMAW process using different classifications and diameters. The filler metals used correspond to different batches of such consumables and it has used a standardized methodology for magnetic determination. The correlation between the two methods seems to work best for NF values between 4 and 8. Errors and the correlation between the two methods applied to determine NF are not acceptable when the electrodes deposit solder metals with high NF values, greater than 18.

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“…After a comprehensive systematic literature review it is found, a general fatigue life estimation and fatigue crack propagation behavior is studied by different researchers. And overall effects of ferrite number (FN) on fatigue life for different materials are explored [29][30][31]. Not one effort is made to find out the differences in percentage generation of ␦-ferrite in different passes of SMAW and its effects on mechanical as well as fatigue properties of SS304L.…”

Section: Introductionmentioning

confidence: 99%

In situ delta ferrite estimation and their effects on FCPR at different orientations of multipass shielded metal arc welded SS304L

Ullah

Shah

2016

Journal of Manufacturing Processes

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Solidification and re-solidification with subsequent phase transformation in different welding zones of multipass weldment play a vital role to define mechanical properties of joint structures. To avoid from penetration defects and inclusion contamination in molten metal pool, multipass shielded metal arc weld-ing (SMAW) of SS304L is performed in this research using E308L filler metal. The objective of this research is to investigate out the multiple welding passes effects on microstructural evolution, in situ delta ferrite percentage and different mechanical properties. A metallurgical microscope is used to examine the delta ferrite phase in austenite. Instead of depending on general ferrite number (FN) obtained through rigorous physical attempts, a MATLAB ® code for image processing is developed to estimate the local percentage of delta ferrite, within the austenitic phase. To reveal delta ferrite effects, its local percentage is discussed in relation to various properties. With the help of this technique, a good estimation is also made to detect the localized delta ferrite morphologies. The fusion zone (FZ) solidified in ferritic-austenitic mode (FA mode) comprises two basic delta ferrite morphologies; lacy and vermicular. Grain growth behavior and ferritic percentage of base metal (BM), heat affected zone (HAZ) and fusion zone (FZ) are discussed in single, double and triple pass weldments. Effects of delta ferrite percentage and morphology on fatigue crack initiation as well propagation are also investigated in different zones of each pass weldment. Fatigue crack propagation rate (FCPR) in different orientation with respect to welding zones is checked and it is noticed that propagation rate is much lower in perpendicular direction as compared to parallel one. Due to specific microstructural pattern, HAZ has greater fatigue crack propagation rate (FCPR) in comparison to BM and FZ. Fatigue crack propagation found highest resistant in triple pass weldment due to high con-centration of lacy ferrites. However, in some cases it is found that crack mechanics is actually responsible instead of microstructural effects.

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The Measurement of Ferrite Number (FN) in Real Weldments — Final Report

Cited by 13 publications

References 0 publications

Ferrite content measurement in super duplex stainless steel welds

Ferrite content measurement in super duplex stainless steel welds

Análisis comparativo en la determinación de ferrita delta para aceros inoxidables austeníticos

In situ delta ferrite estimation and their effects on FCPR at different orientations of multipass shielded metal arc welded SS304L

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