Effect of normalization temperature on the creep strength of modified 9Cr-1Mo steel

Totemeier, T. C.; Tian, Hongli; Simpson, J. A.

doi:10.1007/s11661-006-0096-9

Cited by 42 publications

(16 citation statements)

References 14 publications

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“…Figure 3.13. Effect of normalization temperature on the room-temperature mechanical properties of modified 9Cr-1Mo steel [Totemeier, et al 2006] The creep rupture strength was lower at a normalization temperature of 925ºC than at 1050ºC. This reduction in rupture strength was more pronounced for higher test temperatures and lower stresses as shown in Fig.…”

Section: Mechanical Propertiesmentioning

confidence: 83%

“…For this steel, a normalization treatment (air cooling) is sufficient to produce a fully martensitic structure. However, the normalization temperature can have an effect on the tensile and creep-rupture properties of the steel [Totemeier, et al 2006]. Figure 3.13 shows the effect of normalization temperature on the room-temperature strength and hardness of modified 9Cr-1Mo steel.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

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Preliminary materials selection issues for the next generation nuclear plant reactor pressure vessel.

Natesan

Shankar²,

Shah³

2007

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The NGNP, which is an advanced HTGR concept with emphasis on both electricity and hydrogen production, involves helium as the coolant and a closed-cycle gas turbine for power generation with a core outlet/gas turbine inlet temperature of 900-1000°C. In the indirect cycle system, an intermediate heat exchanger is used to transfer the heat from primary helium from the core to the secondary fluid, which can be helium, nitrogen/helium mixture, or a molten salt. The system concept for the VHTR can be a reactor based on the prismatic block of the GT-MHR developed by a consortium led by General Atomics in the U.S. or based on the PBMR design developed by ESKOM of South Africa and British Nuclear Fuels of U.K.This report has reviewed the available information on candidate materials for the construction of RPV and has made a preliminary assessment of several relevant factors to make a judicious selection of the material for the RPV. Some of the factors addressed in this report are availability of commercial alloys for RPV application, their status in ASME Codes for nuclear service, ASME code compliance during steady state and depressurized conduction cooling conditions, baseline mechanical properties, effects of thermal aging on mechanical properties and code compliance over long term, fabrication and welding issues, global assessment of availability/capability of vendors for RPV procurement, and technology gaps in our knowledge base to address some of the technical issues. The assessment included three primary candidate alloys namely, low alloy steel SA508 (UNS K12042), Fe-2.25Cr-1Mo-0.25V steel (UNS K31835), and modified 9Cr-1Mo steel (UNS K90901) for the RPV. Several conclusions were drawn from this assessment:Baseline Mechanical Properties: There is sufficient database available for the mechanical properties of SA-508 steel. There is limited data available on the thermal aging effects on the mechanical properties and additional information needs development on the long-term aging effects. The steel is approved for use up to 371°C (700°F) under the ASME Code. At present no data is available on the effects of impure helium on the long-term corrosion and mechanical properties of the material.There is adequate tensile data on the Fe-2.25Cr-1Mo-0.25V in the temperature range of interest in NGNP RPV. There is only limited creep data available for the steel and additional data are needed, especially at elevated temperatures that encompass depressurized conduction cooldown conditions. However, substantial data on the creep fatigue properties, thermal aging affects on the mechanical properties, performance characteristics in impure helium, and properties of thick section material are needed prior to its selection for NGNP RPV. Furthermore, the steel is approved under ASME Code Section VIII (for non nuclear applications) and is not approved under Section III for use in nuclear systems.Substantial database on the baseline mechanical properties is currently available for the Modified 9Cr-1Mo steel. Sufficient data are also avail...

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Section: Mechanical Propertiesmentioning

confidence: 83%

Section: Mechanical Propertiesmentioning

confidence: 99%

Preliminary materials selection issues for the next generation nuclear plant reactor pressure vessel.

Natesan

Shankar²,

Shah³

2007

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“…At higher normalizing temperature, considerable grain growth occurred, but at lower normalizing temperature the austenite grain structure was finer. Moreover, normalizing below 900 °C resulted in partially transformed ferrite with patches of martensitic structure [12]. However, the change in the normalizing temperature in the range of 1020-1100 °C can result in different precipitate size distribution(s) that could possibly affect the mechanical behavior of the alloys.…”

Section: As-normalized Microstructurementioning

confidence: 99%

“…There are numerous studies on the normalizing/tempering of Grade 91 steel [11][12][13][14][15], but these studies are limited to few temperatures and times. Thus, this paper has taken about 50 normalizing and tempering conditions to study the relevant microstructural evolution.…”

Section: Introductionmentioning

confidence: 99%

Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel

Shrestha

Alsagabi

Charit

et al. 2015

Metals

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Grade 91 steel (modified 9Cr-1Mo steel) is considered a prospective material for the Next Generation Nuclear Power Plant for application in reactor pressure vessels at temperatures of up to 650 °C. In this study, heat treatment of Grade 91 steel was performed by normalizing and tempering the steel at various temperatures for different periods of time. Optical microscopy, scanning and transmission electron microscopy in conjunction with microhardness profiles and calorimetric plots were used to understand the microstructural evolution including precipitate structures and were correlated with mechanical behavior of the steel. Thermo-Calc™ calculations were used to support the experimental work. Furthermore, carbon isopleth and temperature dependencies of the volume fraction of different precipitates were constructed.

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“…The work has focused on the incorrect normalization temperature. In previous work, normalization below the recommended normalization temperature of 1050 o C resulted in lower creep resistance even though there was no obvious difference in microstructure (at the optical microscopy level) and room temperature tensile properties [7]. This work will further define the critical normalization temperature, below which, creep strength falls to unacceptable levels.…”

Section: Off Normal Heat Treatment and Associated Creep Properties Ofmentioning

confidence: 86%

Assessment of Negligible Creep, Off-Normal Welding and Heat Treatment of Gr91 Steel for Nuclear Reactor Pressure Vessel Application

Ren¹,

Terry²

2006

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ABTRACTTwo different topics of Grade 91 steel are investigated for Gen IV nuclear reactor pressure vessel application. On the first topic, negligible creep of Grade 91 is investigated with the motivation to design the reactor pressure vessel in negligible creep regime and eliminate costly surveillance programs during the reactor operation. Available negligible creep criteria and creep strain laws are reviewed, and new data needs are evaluated. It is concluded that modifications of the existing criteria and laws, together with their associated parameters, are needed before they can be reliably applied to Grade 91 for negligible creep prediction and reactor pressure vessel design. On the second topic, effects of off-normal welding and heat treatment on creep behavior of Grade 91 are studied with the motivation to better define the control over the parameters in welding and heat treatment procedures. The study is focused on off-normal austenitizing temperatures and improper cooling after welding but prior to post-weld heat treatment.

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Effect of normalization temperature on the creep strength of modified 9Cr-1Mo steel

Cited by 42 publications

References 14 publications

Preliminary materials selection issues for the next generation nuclear plant reactor pressure vessel.

Preliminary materials selection issues for the next generation nuclear plant reactor pressure vessel.

Effect of Heat Treatment on Microstructure and Hardness of Grade 91 Steel

Assessment of Negligible Creep, Off-Normal Welding and Heat Treatment of Gr91 Steel for Nuclear Reactor Pressure Vessel Application

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