Analysis of impact toughness scatter in simulated coarse-grained HAZ of E550 grade offshore engineering steel from the aspect of crystallographic structure

Wang, Xiaolei; Wang, Z.Q.; Ma, Xiaoping; Subramanian, S.V.; Xie, Z.J.; Chen, Shang; Li, X.C.

doi:10.1016/j.matchar.2018.03.037

Cited by 68 publications

(29 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…But the crack at 0 t was much more tortuous than those in the other two positions. High angle boundaries greater than 45° were always observed at the positions where cracks were deflected which agrees well with the literature [7,9]. Moreover, when coming across misorientation greater than 45° the secondary crack is not only deflected but shows a zig-zag pattern, as denoted by blue dashed circles in Figure 8d-f.…”

Section: Discussionsupporting

confidence: 91%

“…In contrast, the microstructure at 1/4 t consists of bainite, with carbides aggregating in blocks or plates. This bainite has been identified as mainly granular bainite (GB) together with a small portion of lath bainite (LB), which often appear under continuously cooling condition [7]. These blocky or plate-like clusters aggregated with carbides correspond to the Martensite or Austenite (MA) constitutes that were originally formed during mediate-rate cooling.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Thickness Dependence of Toughness in Ultra-Heavy Low-Alloyed Steel Plate after Quenching and Tempering

Liu

Zhang

2018

Metals

View full text Add to dashboard Cite

Due to the limitations of manufacturing techniques, inhomogeneous microstructures and properties along the thickness direction have been a big challenge for heavy and ultra-heavy plates of quenched and tempered low-alloyed steel. In this study, variation in microstructures and mechanical properties were investigated from the surface to the center of a 130 mm-thick ultra-heavy steel plate. Emphasis was made on toughness performance including impact toughness and crack resisting ability. It was found that the ultimate tensile strength at the plate surface, quarter and center thickness at room temperature are 715, 643 and 618 MPa, respectively. Meanwhile, the ductile-brittle transition temperature defined by fracture appearance for these three plate positions are −100, −30 and −15 °C, respectively. Moreover, the crack resisting ability represented by the nil-ductility temperature are −40, −25 and −10 °C for these three positions respectively. Investigation by field emission scanning electron microscopy (FE-SEM) and electron backscatter diffraction (EBSD) revealed that the plate surface features finer matrix grain and carbide precipitation, as well as greater frequency of high angle misorientation. These microstructural features contribute to enhancing deformability, retarding cleavage initiation and hindering crack propagation, leading to the pronounced increase in the energy for fracture propagation and the overall impact energy as compared to the other two plate positions.

show abstract

Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Thickness Dependence of Toughness in Ultra-Heavy Low-Alloyed Steel Plate after Quenching and Tempering

Liu

Zhang

2018

Metals

View full text Add to dashboard Cite

show abstract

“…This compression can be carried out along three mutually orthogonal axes, and the variants compressed along the same axis belong to one Bain group, thus three Bain groups are formed. According to Bain group, the overall misorientation information of different variant pairs can be effectively reflected [ 32 ]. Theoretically, the minimum misorientation angle formed by the variants from different Bain groups is ~47°, while the variation from the same Bain group can only form a maximum misorientation angle ~21°.…”

Section: Resultsmentioning

confidence: 99%

The Significance of Coherent Transformation on Grain Refinement and Consequent Enhancement in Toughness

Zhao

Dong

et al. 2020

Materials

View full text Add to dashboard Cite

Coherent transformation is considered to be an effective approach to refine the microstructure and enhance toughness of structural steels. However, there are gaps in the knowledge on the key aspects of microstructure that govern toughness. In this regard, a low alloyed experimental steel with lean chemistry was subjected to a simple heat treatment involving austenitization at different temperatures, followed by quenching and tempering to obtain bainitic microstructures with different boundary composition. The microstructure of the four experimental steels was characterized by electron backscattered diffraction and mechanical properties were determined. The study indicated that the density of high angle grain boundaries does not adequately reflect the change of ductile-to-brittle transition temperatures (DBTT) of the experimental steels. Thus, we propose here a new mechanism on reducing DBTT from the perspective of misorientation of boundary, which takes into consideration these aspects in defining DBTT. One is inhibition effect on cleavage fracture by boundaries with high {100}-plane misorientation angles, and the other is ductility improvement by boundaries with high {110}-plane misorientation angles. Furthermore, the contribution of prior austenite grain boundary, packet boundary, block boundary, and sub-block boundary on toughness is also analyzed.

show abstract

“…Os resultados obtidos nos ensaios de impacto Charpy-V (Figuras 9 e 10), parecem indicar que não existem diferenças importantes na tenacidade da ZTA para as diferentes condições estudadas, embora seja destacado que a tenacidade desta região tanto no estado de como soldado quanto após o passe de revenimento seja inferior a das outras regiões da junta soldada no estado de como soldado. No entanto, como existe um elevado grau de dispersão para estes resultados, entende-se ser mais adequada uma avaliação com o critério do valor mínimo obtido nos ensaios, o que segundo Li et al [48] apresenta importância fundamental sob o aspecto de engenharia e pode limitar a aceitação de materiais para alguns casos específicos, dentre eles os componentes de ancoragem [49], uma vez que o valor mínimo pode representar o comportamento de fratura da junta como um todo [50]. Neste caso, a análise das condições estudadas sob o ponto de vista de valor mínimo (36 joules para a condição como soldado, 38 joules após o passe de revenimento e 45 joules após TTPS), mostra um comportamento diferente daquele observado quando da análise do valor médio (Figura 9), permitindo inferir que a realização do TTPS propiciou uma melhoria na tenacidade ao impacto.…”

Section: Propriedades Da Junta Soldadaunclassified

Avaliação de Juntas Soldadas de um Aço Fundido de Alta Resistência para a Indústria Offshore

et al. 2018

View full text Add to dashboard Cite

Resumo Os torpedos de ancoragem são estruturas tubulares de aço carbono soldadas, e que tem sua ligação com as linhas de ancoragem que impedem o movimento das plataformas através de olhais de carregamento que são soldados nos tubos de construção. Como estes olhais apresentam geometria complexa, é importante a utilização de peças fundidas para a fabricação destes componentes, de forma a possibilitar o atendimento da demanda do mercado. Como a literatura técnica sobre este tipo de união soldada é ainda limitada, o presente trabalho estuda o comportamento de juntas soldadas de um aço fundido de alta resistência para utilização em olhais de torpedos de ancoragem de plataformas offshore. Para tanto, foram produzidas juntas soldadas com chanfro em K utilizando um aço de classificação ASTM A 148 Gr. 105-85 com resistência mecânica da ordem de 700 MPa, pelo processo eletrodo revestido, na posição plana, com preaquecimento de 200 °C e energia de soldagem média de 1,5 kJ/mm. Após a soldagem, foi realizado tratamento térmico pós-soldagem (TTPS) consistindo de aquecimento a 620 °C por 1 hora com resfriamento ao ar. As propriedades foram avaliadas por ensaios de tração, dureza, impacto Charpy-V e metalográficos por microscopia óptica e eletrônica de varredura com utilização da técnica de EBSD (eléctron backscatering difraction), tanto na condição de como soldado quanto após TTPS. Os resultados revelaram que, embora as propriedades mecânicas obtidas na junta soldada atendam os requisitos para a aplicação em todas as condições de análise, recomenda-se a execução do TTPS para alívio das tensões residuais e promover um revenimento da martensita de alta dureza do último passe de soldagem. Adicionalmente, verificou-se ser possível obter propriedades similares as de juntas soldadas de aços laminados usualmente utilizados em componentes de ancoragem.

show abstract

Analysis of impact toughness scatter in simulated coarse-grained HAZ of E550 grade offshore engineering steel from the aspect of crystallographic structure

Cited by 68 publications

References 22 publications

Thickness Dependence of Toughness in Ultra-Heavy Low-Alloyed Steel Plate after Quenching and Tempering

Thickness Dependence of Toughness in Ultra-Heavy Low-Alloyed Steel Plate after Quenching and Tempering

The Significance of Coherent Transformation on Grain Refinement and Consequent Enhancement in Toughness

Avaliação de Juntas Soldadas de um Aço Fundido de Alta Resistência para a Indústria Offshore

Contact Info

Product

Resources

About