Grain refinement and hardness distribution in cryogenically cooled ferritic stainless steel welds

Amuda, M.O.H.; Mridha, S.

doi:10.1016/j.matdes.2012.12.008

Cited by 49 publications

(18 citation statements)

References 14 publications

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“…The faster cooling rate provides a rapid heat dissipation which can generate equiaxed microstructures in the weld metal. Amuda and Mridha (2013) found that the equiaxed grain structure is related to the faster cooling rates at the grain coarsening temperature (Villaret et al, 2013). Higher magnifications of the weld metal (Fig.…”

Section: Macro and Microstructural Characteristics Of The Welded Jointsmentioning

confidence: 89%

Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

et al. 2016

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Welds without filler metal and welds using a conventional austenitic stainless steel filler metal (ER308L) were performed to join a ferritic stainless steel with Gas Tungsten Arc Welding process (GTAW). Welding parameters were adjusted to obtain three different heat input values. Microstructure reveals the presence of coarse ferritic matrix and martensite laths in the Heat Affected Zone (HAZ). Dilution between filler and base metal was correlated with the presence of austenite, martensite and ferrite in the weld metal. Weld thermal cycles were measured to correlate the microstructural transformation in the HAZ. Microhardness measurements (maps and profiles) allow to identify the different zones of the welded joints (weld metal, HAZ, and base metal). Comparing the base metal with the weld metal and the HAZ, a hardness increment (~172 HV 0.5 to ~350 HV 0.5 and ~310 HV 0.5 , respectively) was observed, which has been attributed to the martensite formation. Tensile strength of the welded joints without filler metal increased moderately with respect to base metal. In contrast, ductility was approximately 25% higher than base metal, which provided a toughness improvement of the welded joints. RESUMEN:Efecto del calor de aporte sobre la transformación microestructural y las propiedades mecánicas en soldadura GTAW de un acero inoxidable ferrítico 409L. Se llevaron a cabo soldaduras sin material de aporte y empleando un electrodo convencional (ER308L) para unir un acero inoxidable ferrítico, empleando el proceso de soldadura de arco con electrodo de tungsteno (GTAW). Los parámetros de soldadura fueron ajustados para obtener tres valores diferentes de calor de aporte. La microestructura revela la presencia de una matriz ferrítica gruesa y placas de martensita en la Zona Afectada por el Calor (ZAC). La dilución entre el metal base y de aporte fue correlacionada con la presencia de austenita, martensita y ferrita en el metal de soldadura. Los ciclos térmicos de la soldadura fueron medidos para correlacionar la transformación microestrutural en la ZAC. Mediciones de microdureza (mapas y perfiles), permitieron identificar las diferentes zonas de las uniones soldadas (metal base, ZAC y metal de soldadura). Se observó un incremento de dureza en el metal de soldadura (~350 HV 0,5 ) y en la ZAC (~310 HV 0,5 ), en relación al metal base (~172 HV 0,5 ), que se ha atribuido a la formación de martensita. La resistencia a la tensión de las uniones soldadas sin metal de aporte aumentó ligeramente con respecto al metal base. En cambio, la ductilidad se incrementó aproximadamente un 25% en relación al material base, lo cual mejoró la tenacidad de las uniones.

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Section: Macro and Microstructural Characteristics Of The Welded Jointsmentioning

confidence: 89%

Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

et al. 2016

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“…[4][5][6]. They are considered as a low cost substitute to austenitic steel owing to its low nickel content [7,8].…”

Section: Introductionmentioning

confidence: 99%

Effect of post weld heat treatment on metallurgical and mechanical properties of electron beam welded AISI 409 ferritic steel

2020

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The applicability of ferritic stainless steel is restricted due to its low weldability, and this can be attributed to the severe grain growth in the weld zone during the solidification of the weld pool and formation of fully ferritic structure. This study aims to investigate the weldability of 18 mm thick AISI 409 ferritic stainless steel plates using an electron beam welding process without the use of filler metal. The joints were investigated for metallography characterization (microstructure, macrostructure, and microhardness) and mechanical behavior (tensile strength and impact toughness) in as-welded condition and after post-weld heat treatment at 550 ºC for 75 minutes. The weld zone exhibited large columnar grains in the direction perpendicular to the weld centerline and got refined after post-weld heat treatment. The ultimate tensile strength, yield strength, and microhardness of the weld zone were found higher than the base metal. The impact toughness of weld zone was found to be reduced by 45%, but the post-weld heat treatment improved the toughness by 40%. Results revealed that the electron beam welding process could be successfully employed for welding of AISI 409 ferritic stainless steel, which will increase its application range that requires thicker section of welded plates. Post-weld heat treatment was found to be advantageous for improving the microstructure and mechanical properties.

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“…Jariyaboon et al [9] found that carbon dioxide cooling reduced the width of the HAZ in an AA2024-T351 aluminum alloy welded joint. Amuda and Mridha et al [10,11] performed liquid nitrogen cooling during the welding of ferritic stainless steel. The size of the weld and HAZ were reduced, and the grains were refined.…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolution and grain refinement mechanism of Inconel 601H alloy welded joints under compound physical fields of vibration and rapid cooling

Shi

Zheng

et al. 2020

Mater. Res. Express

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The method and mechanism of suppressing grain growth and microstructure coarsening in nickelbased alloy welded joints were studied herein. First, sodium thiosulfate was used to simulate the crystallization processes of the welding pool. Then, on this basis, the compound physical fields of lowfrequency mechanical vibration and rapid cooling on the microstructure of the Inconel 601H alloy welded joint were investigated. Finally, the joint grain refinement behavior and mechanism were analyzed based on the experimental and physical simulation results. The experimental results indicate that only the low-frequency mechanical vibration acting in the welding process caused the center of the weld to be mostly composed of equiaxed grains. The epitaxial solidification phenomenon near the fusion line disappeared, but there were still many fine columnar grains in the upper part of the weld edge. The heat-affected zone (HAZ) morphology was eventually dominated by coarse grains, and the width of the HAZ increased. However, with the compound physical fields, the weld was mainly composed of equiaxed grains, and the grain size and width of the HAZ decreased. Thus, an increased hardness distribution was also achieved. Moreover, the γ′ phase exhibited a dispersed distribution and the alloy elements were very uniformly distributed in the γ′ phase, which helped to prevent the initiation of hot cracking of the weld comprising nickel-based alloys. In addition, the results demonstrated that the generation of additional crystal nuclei and the increase in the cooling rate from the compound physical fields were the main mechanisms for the grain refinement. OPEN ACCESS RECEIVED

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Grain refinement and hardness distribution in cryogenically cooled ferritic stainless steel welds

Cited by 49 publications

References 14 publications

Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

Effect of post weld heat treatment on metallurgical and mechanical properties of electron beam welded AISI 409 ferritic steel

Microstructure evolution and grain refinement mechanism of Inconel 601H alloy welded joints under compound physical fields of vibration and rapid cooling

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