Comparison of the Properties of the HK-40 and HP-45 Cast Heat-Resistant Alloys

Roach, D.B.; VanEcho, J. A.

doi:10.1520/stp28447s

Cited by 13 publications

(5 citation statements)

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“…HP alloys share common features with their predecessor HK series ( ∼ Fe-20Ni-25Cr-0.4C wt-%, plus minor additions). Comparisons have already been performed [3,12], and we will focus on both categories when necessary, which will help to better understand the specific phenomena occurring in HP alloys.…”

Section: Microstructure and Phase Transformations In Hp Alloys: Backg...mentioning

confidence: 99%

Phase transformations in Fe–Ni–Cr heat-resistant alloys for reformer tube applications

Tancret

Laigo

Christien

et al. 2018

Materials Science and Technology

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Fe–35Ni–25Cr–0.4C alloys with different compositions are aged between 750 and 1150°C up to ∼10,000 h. As-cast microstructure contains interdendritic carbides of type M7C3 (‘Cr7C3’) and MC (‘NbC’). At service temperatures, M7C3 transform into M23C6 (‘Cr23C6’) within hours. Then, a hardening precipitation of secondary intragranular M23C6 occurs over hundreds of hours, the nose of the ‘temperature-time-hardening’ curve being around 1000°C. G phase forms after long aging; its solvus temperature and formation kinetics depend on silicon content. Z phase is observed after long aging at 950°C or above. G and Z phases form at the expense of MC. Very long aging causes nitridation under air, with first a transformation of M23C6 into chromium-rich M2X carbonitrides (X = C,N), then of MC into chromium-rich MX carbonitrides.

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Section: Microstructure and Phase Transformations In Hp Alloys: Backg...mentioning

confidence: 99%

Phase transformations in Fe–Ni–Cr heat-resistant alloys for reformer tube applications

Tancret

Laigo

Christien

et al. 2018

Materials Science and Technology

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“…In terms of microstructure and its relation to creep, HP alloys share common traits with the older HK alloys (∼Fe–20Ni–25Cr–0.4C wt-%, plus minor additions) [3,13]. We will therefore describe findings on both series when needed, which can help to better understand the specific characteristics of HP alloys.…”

Section: Microstructure and Creep Resistance Of Hp Alloys: Backgroundmentioning

confidence: 99%

Creep resistance of Fe–Ni–Cr heat resistant alloys for reformer tube applications

Tancret

Laigo

Furtado

2019

Materials Science and Technology

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Relations between microstructure, phase transformations and creep resistance of austenitic Fe–Ni–Cr alloys are investigated. As-cast alloys with different silicon contents and an ex-service tube are submitted to laboratory agings to trigger specific phase transformations, and subsequently creep-tested at 950°C under stresses of 24–48 MPa. As-cast microstructures contain interdendritic chromium-rich M7C3 carbides with niobium-rich MC carbides. After aging at 950°C, primary M7C3 carbides transform into chromium-rich M23C6 carbides, associated to a loss in creep strength. The G phase present in the ex-service alloy is reversed into MC carbides by a heat treatment at 1100°C, associated to a slight decrease in creep resistance. Besides, the addition of silicon is highly detrimental to creep strength. Results can be used for alloy design.

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“…Cross-weld creep testing of most Ni-based Inconel and stainless steel alloys indicates that weld strengths are usually in the range of 50-100% of those of the Alloy 800H base material [4][5][6]. Commonly used filler materials for Alloy 800H welding, such as Inconel 82, 182, 188, and SS 304 alloys, exhibit slightly lower creep rupture stresses than Alloy 800H base metal, in the range of 538 to 760 • C, regardless of whether the exposure time is short or long [5,7,8]. A recent investigation at the Idaho National Laboratory using Inconel 617 filler material did not demonstrate an improvement in creep rupture properties [9].…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Creep and Microstructure Evolution of Alloy 800H Weldments with Inconel 625 and Haynes 230 Filler Materials

Li,

Xiao,

Walters

et al. 2024

Applied Sciences

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Alloy 800H stands as one of the few code-qualified materials for fabricating in-core and out-of-core components operating in high-temperature reactors. Welding is a common practice for assembling these components; however, the selection of a suitable filler material is essential for enhancing the high-temperature creep resistance of Alloy 800H weldments in high-temperature applications. In this study, Inconel 625 and Haynes 230 filler materials were used to weld Alloy 800H plates by employing the gas tungsten arc welding technique. The high-temperature tensile and creep rupture properties, microstructural stability, and evolution of the weldments after high-temperature exposure were investigated and compared with those of Alloy 800H. The results show that both weldments exhibit enhanced tensile and creep behavior at 760 °C. The creep rupture times of the weldments with Inconel 625 filler and Haynes 230 filler materials were about two and three time longer, respectively, than those of Alloy 800H base metal when tested at 80 MPa and 760 °C. Carbides (MC and M23C6) were commonly observed in the microstructures of both the weld and base metals in the two weldments after high-temperature creep tests. However, the Inconel 625 filler weldment displayed detrimental δ and Laves phases in the fusion zone, and these precipitates could be potential sites for initiating cracks following prolonged high-temperature exposure. This study shows that the weldment with Haynes 230 filler material exhibit better phase stability and creep rupture properties than the one with Inconel 625, suggesting its potential for use as a candidate filler material for Alloy 800H for further investigation. This finding also emphasizes the critical consideration of microstructural evolutions and phase stability in evaluating high-temperature materials and their weldments in high-temperature reactor applications.

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Comparison of the Properties of the HK-40 and HP-45 Cast Heat-Resistant Alloys

Cited by 13 publications

References 0 publications

Phase transformations in Fe–Ni–Cr heat-resistant alloys for reformer tube applications

Phase transformations in Fe–Ni–Cr heat-resistant alloys for reformer tube applications

Creep resistance of Fe–Ni–Cr heat resistant alloys for reformer tube applications

High-Temperature Creep and Microstructure Evolution of Alloy 800H Weldments with Inconel 625 and Haynes 230 Filler Materials

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