Friction Stir Welding of High Phosphorus Weathering Steel —Weldabilities, Microstructural Evolution and Mechanical Properties

Kawakubo, Takumi; Nagira, Tomoya; Ushioda, Kohsaku; Fujii, Hidetoshi

doi:10.2355/isijinternational.isijint-2021-007

Cited by 16 publications

(7 citation statements)

References 51 publications

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“…Three kinds of steels with high wt-% P were newly developed to evaluate the microstructure and mechanical properties produced by FSW [28, 29]. The conventional weathering mild steel SMA490AW and SPA-H joined under the same welding conditions were also referred for comparison [27].…”

Section: Methodsmentioning

confidence: 99%

“…The studied steels in this research are featured with wt-% P of about 0.1%, and it is expected to join the weathering mild steels with higher wt-% P by FSW. Kawakubo [28, 29] studied the microstructure, toughness and tensile strength of mild steels joined by FSW with high wt-% P (as high as 0.3%). In spite of outstanding mechanical properties as described in this research, the yield and fracture mechanism of steels with different wt-% P are not fully understood.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and mechanical properties of friction stir welded high phosphorus weathering steel

Wang

Tsutsumi

Kawakubo

et al. 2022

Science and Technology of Welding and Joining

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The mild steel with low phosphorus is vulnerable to corrosion while higher phosphorus often results in hot crack by fusion welding. The present study evaluated microstructures and mechanical properties of high phosphorus steels joined by friction stir welding below the A 1 temperature. The microstructure was analysed considering various phosphorus contents, and mechanical properties were assessed by digital image correlation. The results suggest that alloying elements (nickel, chromium and niobium) contribute to the refinement of pearlite in the base metal and cementite in the stir zone. The increasing phosphorus improves the microhardness and strength of friction stir welded joints but weakens the ductile behaviour. The added alloying elements can enhance the ductile behaviour and mechanical strength at the same time.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanical properties of friction stir welded high phosphorus weathering steel

Wang

Tsutsumi

Kawakubo

et al. 2022

Science and Technology of Welding and Joining

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View full text Add to dashboard Cite

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“…摩擦攪拌接合 (FSW: Friction stir welding) は，回転ツールの摩擦熱と攪拌作用を利用した固相接合技術である．入熱量が低く，溶接ひずみが小さいなどの優れた特徴を持つことから，まずは適用が比較的容易なアルミニウム合金などの低融点金属 [1][2][3][4][5] で研究が行われ，ツール材質の改良などに伴い鉄鋼材料などの高融点材料への適用も研究されている [6][7][8][9][10][11][12][13] ．著者らはこれまでに，低合金鋼 [14][15][16] や Ni-C 合金鋼 17,18)…”

Section: 緒言unclassified

Prediction of Material Flow Behavior in Stir Zones of Friction Stir Welded 6％Ni Carbon Steel Based on Texture Analysis

Miura

Fujii

Ushioda

2022

J. Japan Inst. Metals and Materials

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Friction stir welding (FSW) was performed under the two welding conditions (rotation speed-traveling speed) of 150 rpm-100 mm/min and 200 rpm-400 mm/min using 6 mass％Ni-0.63 mass％C steels. The slightly lower peak welding temperature and significantly higher cooling rate was obtained under the condition of 200 rpm-400 mm/min. Texture analysis for retained austenite and martensite revealed that the parent austenite had simple shear texture, which lead to the formation of {110}<111> texture in transformed martensite. Moreover, material flow behavior as a function of distance from the top surface in the stir zone was analyzed based on textures obtained by EBSD measurement. A concentric material flow, which has smaller radius as the far from the tool shoulder, was formed under the condition of 150 rpm-100 mm/min. On the other hand, a heterogeneous material flow with the center shifted to the retreating side was formed under the condition of 200 rpm-400 mm/min. In addition, a different vertical component of material flow was predicted to occur under each welding conditions.

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“…Recently, applications for high-melting-point metals such as steels have been investigated owing to improvements in tool materials. [5][6][7][8][9][10][11][12] In many cases involving the FSW of steels, a phase transformation occurs via frictional heating and cooling during and after FSW. In other words, austenite which transforms from ferrite during stirring undergoes dynamic recrystallization, followed by phase transformation from austenite to ferrite and/or martensite during cooling after the stirring stage.…”

Section: Introductionmentioning

confidence: 99%

Effects of Carbon Content and Austenite Grain Size on Retained Austenite Fraction in Stir Zone of Friction Stir Welded 6%Ni Carbon Steels

2022

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Friction stir welding (FSW) was performed under the two welding conditions (rotation speed-traveling speed) of 150 rpm-100 mm/min and 200 rpm-400 mm/min using 6 mass%Ni steels with different carbon contents from 0.14 mass% to 0.63 mass%. The slightly lower peak welding temperature and the higher cooling rate were predicted under the condition of 200 rpm-400 mm/min. The effects of carbon content and prior austenite grain size on retained austenite fraction in the stir zones were evaluated. When carbon content was 0.30 mass% or more, a fine microstructure consisting of lath martensite and retained austenite was formed in the stir zone. Irrespective of welding conditions, the amount of retained austenite increased with the increase of carbon content. More retained austenite was obtained at the stir zone under the 200 rpm-400 mm/min condition, which resulted from rapid cooling and finer prior austenite grains compared with the condition of 150 rpm-100 mm/min. The effect of the prior austenite grain size on the amount of retained austenite was successfully extracted, and the finer austenite grain size was concluded to play an important role to stabilize austenite by analyzing the difference in the martensitic start temperatures predicted based on the chemical composition and the retained austenite fraction based on Koistinen-Marburger equation.

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Friction Stir Welding of High Phosphorus Weathering Steel —Weldabilities, Microstructural Evolution and Mechanical Properties

Cited by 16 publications

References 51 publications

Microstructure and mechanical properties of friction stir welded high phosphorus weathering steel

Microstructure and mechanical properties of friction stir welded high phosphorus weathering steel

Prediction of Material Flow Behavior in Stir Zones of Friction Stir Welded 6％Ni Carbon Steel Based on Texture Analysis

Effects of Carbon Content and Austenite Grain Size on Retained Austenite Fraction in Stir Zone of Friction Stir Welded 6%Ni Carbon Steels

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