Temper embrittlement of 9%Ni low carbon steel

Tavares, Sérgio Souto Maior; Cunha, Rachel Pereira Carneiro da; Barbosa, Cássio; Andia, J.L.M.

doi:10.1016/j.engfailanal.2018.11.011

Cited by 14 publications

(6 citation statements)

References 8 publications

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“…2. Tempering at 400°C caused severe embrittlement in the 9% Ni steels, as expected from previous works [1,5,9]. In 9% Ni low carbon steels the embrittlement is not coincident with any hardening increase.…”

Section: Resultssupporting

confidence: 84%

“…This combination provides very high impact toughness Charpy at −196°C. Although one of the objectives of the tempering treatment is to increase the toughness of the steels, un-correct tempering temperature selection may cause a brittle behaviour, decreasing severely the low temperature toughness [5]. Temper embrittlement of 9%Ni steels is reported to occur in the 370-540°C range.…”

Section: Introductionmentioning

confidence: 99%

“…Fracture surface of (a) QT585F showing cleavage and intergranular cracking in the center of specimen, indicating low toughness; (b) QT585 with dimples indicating high toughness.Fig.5shows the microstructural characterization by SEM of specimen quenched and tempered at 400 o C (QT400). The temper embrittlement of 9%Ni steel is attributed to intergranular Fe3C carbides and/or intergranular phosphorus segregation[5,10].…”

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confidence: 99%

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Temper embrittlement of 9%Ni low carbon steel and nondestructive inspection by magnetic Barkhausen noise

et al. 2021

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9% Ni and low carbon steel is used in cryogenic services in oil and gas industries. The final mechanical properties are adjusted by quenching and tempering heat treatments. However, the un-correct tempering may cause temper embrittlement, with drastic decrease of toughness at cryogenic temperatures. In this study, specimens tempered at 350°C, 400°C and 450°C showed very low toughness at low temperature (-196°C) due to temper embrittlement. Specimens slowly cooled from the tempering temperature (565°C, 585°C and 605°C) also showed toughness reduction in comparison with specimens tempered at the same temperature and cooled in water. The brittle fracture was characterized by intergranular cracks and cleavage. Magnetic Barkhausen Noise (MBN) inspection was conducted to verify if this technique can be used to detect the temper embrittlement in 9Ni steels. The root mean square (RMS) of the MBN signal was higher in specimens as quenched and in specimens tempered in the temper embrittlement range (350°C-500°C) than in specimens which were correctly tempered (565°C-605°C and water cooled). Comparing specimens tempered at 565 and 585°C range and slowly cooled with those which were water cooled, the RMS(MBN) was higher in the former group, which presented the lower toughness. However, the MBN inspection could not separate specimens tempered at 605°C slowly and rapidly, which can be related to the higher austenite volume fraction measured in the specimen slowly cooled.

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Section: Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Temper embrittlement of 9%Ni low carbon steel and nondestructive inspection by magnetic Barkhausen noise

et al. 2021

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“…McMahon proposed that during tempering in the embrittlement temperature range, Fe3C precipitates along the grain boundaries, and since impurities have low solubility in Fe3C, impurities are rejected and concentrated at the interface during carbide precipitation. This creates favorable pathways for crack propagation along the interface, constituting a non-equilibrium segregation process [19,20]. Rapid cooling after tempering On the other hand, during the tempering process, the precipitation of Fe 3 C at grain boundaries and the segregation of impurity atoms lead to interface weakening and brittle fracture, as depicted in Figure 12.…”

Section: Impact Of Cooling Rate On Crack Propagationmentioning

confidence: 99%

Regulation Law of Tempering Cooling Rate on Toughness of Medium-Carbon Medium-Alloy Steel

Yang,

Xu,

Zhao

et al. 2023

Materials

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Temper embrittlement is a major challenge encountered during the heat treatment of high-performance steels for large forgings. This study investigates the microstructural evolution and mechanical properties of Cr-Ni-Mo-V thick-walled steel, designed for large forgings with a tensile strength of 1500 MPa, under different tempering cooling rates. Optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) were employed to analyze the microstructural features. The results demonstrate that the embrittlement occurring during air cooling after tempering is attributed to the concentration of impurities near Fe3C at the grain boundaries. The low-temperature impact toughness at −40 °C after water quenching reaches 29 J due to the accelerated cooling rate during tempering, which slows down the diffusion of impurity elements towards the grain boundaries, resulting in a reduced concentration and dislocation density and an increased stability of the grain boundaries, thereby enhancing toughness. The bainite content decreases and the interface between martensite and bainite undergoes changes after water quenching during tempering. These alterations influence the crack propagation direction within the two-phase microstructure, further modifying the toughness. These findings contribute to the understanding of temper embrittlement and provide valuable guidance for optimizing heat treatment processes to enhance the performance of high-performance steels in large forgings.

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“…Penelitian lain perlakuan panas baja dengan kandungan Mn 5,42 % pada tempering suhu intercritical pada 625° C dan 665° C, ketangguhan impak meningkat dibandingkan dengan tempering pada 570 ° C [2]. Penelitian lain perlakuan panas baja paduan tinggi sangat berpengaruh pada perubahan struktur mikro khususnya fasa martensit yang dibentuk oleh pengendapan elemen krom sebagai pembentuk karbida [3]- [5].…”

Section: Pendahuluanunclassified

Pengaruh Proses Hardening Tempering Terhadap Kekerasan, Struktur Mikro Dan Impak Pada Baja Paduan Rendah

Chamim

2021

AME

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Baja paduan rendah banyak digunakan untuk material khusus salah satunya material tahan abrasif. Ketahanan abrasif didapatkan dari nilai kekerasan yang tinggi. Meningkatnya kekerasan akan mengakibatkan kerugian karena cenderung rapuh sehingga perlu proses lanjutan yaitu temper. Penelitian ini dilakukan dengan cara memanaskan spesimen pada temperatur austenit 800°C dan 850°C dengan holding 15 menit kemudian didinginkan dengan media oli dan ditemper pada temperatur 300°C dengan holding 15menit didinginkan pada udara terbuka. Pada spesimen yang telah mengalami pemanasan dan pendinginan tersebut kemudian dilakukan pengujian Kekerasan, Impak dan struktur mikro untuk mengetahui perubahan sifat dari baja paduan rendah. Hasil pengujian terlihat susunan martensit temper dan jaringan krom karbida sebelum adanya proses perlakuan panas. Martensit temper memiliki kekuatan akan tetapi ada sedikit keuletan didalamnya karena hasil proses tempering. Karbida krom memiliki sifat sangat keras yang terbentuk setelah proses quenching bertujuan untuk mempertahankan kekuatan material. setelah proses perlakuan panas, material paduan akan berubah sifat fisik dan mekaniknya. Nilai kekerasan sangat berpengaruh terhadap penyerapan energi. Kekerasan semakin tinggi akan menurunkan nilai penyerapan energi.

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Temper embrittlement of 9%Ni low carbon steel

Cited by 14 publications

References 8 publications

Temper embrittlement of 9%Ni low carbon steel and nondestructive inspection by magnetic Barkhausen noise

Temper embrittlement of 9%Ni low carbon steel and nondestructive inspection by magnetic Barkhausen noise

Regulation Law of Tempering Cooling Rate on Toughness of Medium-Carbon Medium-Alloy Steel

Pengaruh Proses Hardening Tempering Terhadap Kekerasan, Struktur Mikro Dan Impak Pada Baja Paduan Rendah

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