Considerations in development of CCT diagrams for complex ferritic materials

Siefert, John; Leister, Brett M.; DuPont, J. N.

doi:10.1179/1743284714y.0000000626

Cited by 10 publications

(6 citation statements)

References 6 publications

(6 reference statements)

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“…A CCT diagram for Grade 23 has recently been developed and published to address this need. 73 A better understanding is needed on the creep rupture behaviour of each alloy from cross-weld creep tests. Grade 23 has been observed to fail by Type IIIa, Type IV and mixed failure modes.…”

Section: Summary and Future Research Needsmentioning

confidence: 99%

Microstructural evolution and mechanical properties of Grades 23 and 24 creep strength enhanced ferritic steels

DuPont

Siefert

Shingledecker

2016

International Materials Reviews

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Grades 23 and 24 creep strength enhanced ferritic (CSEF) steels are relatively new materials that have been designed with improved high-temperature strength compared to conventional 2.25Cr-1Mo alloys. These new steels share alloying strategies that were used in the past for CrMo derivatives such as the CrMoV steels. Grades 23 and 24 are often grouped with similar CSEF steels in terms of mechanical properties and fabrication characteristics. However, recent experience indicates that these alloys require more unique care to ensure adequate properties for the intended service in both the base metal and welds. The differences in behaviour between these new steels and more conventional CrMo steels can be attributed to relatively minor variations in composition that lead to rather significant differences in microstructure. This review summarises technical information and practical experience on the manufacture and use of Grades 23 and 24 CSEF steels for power generation applications. Factors that influence the microstructure and strength of base metal are discussed for each alloy along with influences from common fabrication processes such as welding and bending. The results of this review provides manufacturers, fabricators and end users with information that can be applied to help ensure optimal performance of these steels in high-temperature applications associated with power generation.

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Section: Summary and Future Research Needsmentioning

confidence: 99%

Microstructural evolution and mechanical properties of Grades 23 and 24 creep strength enhanced ferritic steels

DuPont

Siefert

Shingledecker

2016

International Materials Reviews

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“…For pipeline steels in welding study of phase transformation behavior becomes very critical due to repetitive transformations of α - ferrite and γ - austenite into each other matrix. Dilatometry is a powerful thermo-analytical method that can be used to determine the phase transformation of steels for various weld thermal cycles (Zhao et al , 2002; Siefert et al , 2015). It monitors and determines the dimensional change (ΔD/ D 0 ) associated with phase transformation (Van Bohemen, 2013).…”

Section: Introductionmentioning

confidence: 99%

The structural integrity of high-strength welded pipeline steels: a review

Singh

Shukla

Kumar

et al. 2020

IJSI

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PurposeThe key purpose of conducting this review is to identify the issues that affect the structural integrity of pipeline structures. Heat affected zone (HAZ) has been identified as the weak zone in pipeline welds which is prone to have immature failuresDesign/methodology/approachIn the present work, literature review is conducted on key issues related to the structural integrity of pipeline steel welds. Mechanical and microstructural transformations that take place during welding have been systematically reviewed in the present review paper.FindingsKey findings of the present review underline the role of brittle microstructure phases, and hard secondary particles present in the matrix are responsible for intergranular and intragranular cracks.Research limitations/implicationsThe research limitations of the present review are new material characterization techniques that are not available in developing countries.Practical implicationsThe practical limitations are new test methodologies and associated cost.Social implicationsThe fracture of pipelines significantly affects the surrounding ecology. The continuous spillage of oil pollutes the land and water of the surroundings.Originality/valueThe present review contains recent and past studies conducted on welded pipeline steel structures. The systematic analysis of studies conducted so far highlights various bottlenecks of the welding methods.

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“…The gradual expansion (before A c1 & after A c3 ) during heating and gradual contraction (before A r3 & after A r1 ) during cooling occur due to thermal expansion and contraction receptively [13]. Since the conversion of austenite into product phases is cooling rate dependent, the first derivative analysis of the cooling curve is performed to get this information [20][21][22]. But, the removal of noise is essential to get a smooth derivative curve.…”

Section: Dilatometry Curvementioning

confidence: 99%

Physical simulation on Joining of 700 MC steel: A HAZ and CCT curve study

Roshan¹,

Naik²,

Saxena³

et al. 2022

Mater. Res. Express

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In the present work, a coarse grain heat-affected zone (CGHAZ) was simulated by Gleeble 3800 thermo-mechanical simulator. A continuous cooling transformation (CCT) diagram was generated from the results of the dilatometer, hardness, and microstructure analysis. The heating rate of 100°C/s, the peak temperature of 1300°C, the holding time of one second, and thirteen different cooling conditions representing the actual welding condition were chosen here for simulation where the cooling rate was controlled by t8/3. At slow cooling rate ferrite, cementite, pearlite, and bainite were obtained. At a medium cooling rate, ferrite, bainite, and a small amount of martensite were observed. At a fast-cooling rate i.e., 100°Cs-1 fully martensite was obtained. The obtained hardness values were 225 HV, 263 HV, and 342 HV for slower, medium, and fast cooling rates respectively. The increase in hardness value shows that the amount of non-diffusional phases increases with an increase in cooling rate. The CCT curve shows the range of cooling rate and phase transformation temperature of ferrite, bainite, and martensite.

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Considerations in development of CCT diagrams for complex ferritic materials

Cited by 10 publications

References 6 publications

Microstructural evolution and mechanical properties of Grades 23 and 24 creep strength enhanced ferritic steels

Microstructural evolution and mechanical properties of Grades 23 and 24 creep strength enhanced ferritic steels

The structural integrity of high-strength welded pipeline steels: a review

Physical simulation on Joining of 700 MC steel: A HAZ and CCT curve study

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