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Investigation of hardening mechanisms and size effects in proton-irradiated HT-9 steels

Journal Article · · Journal of Nuclear Materials

Ferritic/martensitic steels, such as HT-9, are known for their complex microstructural features and mechanical properties. Here in this paper, in-situ micro-tensile tests and traditional fractography methods were utilized to study the fracture behavior of proton-irradiated HT-9 steels. First, to evaluate the viability of micro-tensile tests for nuclear material qualification process, meso-tensile tests on as-received HT-9 steels were performed. Fracture mechanisms of unirradiated HT-9 steels at both length scales were compared and underlying mechanisms discussed. The direct comparison of micro- and meso-scale data shows a distinctive size effect demonstrated by the increase in yield stress (YS). Upon completion of initial assessment, specimens were irradiated with 4 MeV+ protons to three fluences, all of which were lower than 0.01 displacements per atom (dpa). As expected, the YS increases with irradiation. However, at 7 × 10-3 dpa, the reversal of the trend was observed, and the YS exhibited sharp decline. We demonstrate that at lower length scales, grain structure has a more profound impact on the mechanical properties of irradiated materials, which provides information needed to fill in the gap in current understanding of the HT-9 fracture at different length scales.

Research Organization:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC04-94AL85000
OSTI ID:
1769911
Report Number(s):
SAND--2021-2046J; 693974
Journal Information:
Journal of Nuclear Materials, Journal Name: Journal of Nuclear Materials Vol. 548; ISSN 0022-3115
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (40)

Large and Small Scale Materials Testing of HT-9 Irradiated in the STIP Irradiation Program journal November 2010
Mechanical Performance of Ferritic Martensitic Steels for High Dose Applications in Advanced Nuclear Reactors journal December 2012
Towards Bridging the Experimental Length-Scale Gap for Tensile Tests on Structural Materials: Lessons Learned from an Initial Assessment of Microtensile Tests and the Path Forward journal November 2019
Irradiation hardening in copper and nickel journal October 1960
Influence of specimen size and microstructure on the fracture toughness of a martensitic stainless steel journal January 1984
The mumechanical mechanisms of cleavage fracture in martensitic stainless steels journal May 1984
Microstructure-mechanical property relations in HT-9 journal March 1987
Analysis of cleavage fracture behavior in HT-9 with a statistical model journal July 1988
Dose dependence of the microstructural evolution in neutron-irradiated austenitic stainless steel journal November 1993
An evaluation of low temperature radiation embrittlement mechanisms in ferritic alloys journal June 1994
Fracture toughness of irradiated HT-9 for structural applications journal November 1985
Shear punch and tensile measurements of mechanical property changes induced in various austenitic alloys by high-energy mixed proton and neutron irradiation at low temperatures journal December 2000
The mechanical properties of 316L/304L stainless steels, Alloy 718 and Mod 9Cr–1Mo after irradiation in a spallation environment journal July 2001
Microstructure of irradiated ferritic/martensitic steels in relation to mechanical properties journal December 2002
High temperature tensile testing of modified 9Cr–1Mo after irradiation with high energy protons journal May 2003
Tensile properties of ferritic/martensitic steels irradiated in HFIR, and comparison with spallation irradiation data journal May 2003
Fracture toughness and tensile behavior of ferritic–martensitic steels irradiated at low temperatures journal October 1998
Influence of delta ferrite and dendritic carbides on the impact and tensile properties of a martensitic chromium steel journal October 1998
Effects of focused ion beam milling on the compressive behavior of directionally solidified micropillars and the nanoindentation response of an electropolished surface journal January 2009
Ferrite slip system activation investigated by uniaxial micro-tensile tests and simulations journal March 2018
Investigation of microstructure and mechanical properties of low dose neutron irradiated HT-9 steel journal March 2014
Tensile testing of EP-823 and HT-9 after irradiation in STIP II journal September 2006
The effects of fast reactor irradiation conditions on the tensile properties of two ferritic/martensitic steels journal September 2006
An exploratory study to determine applicability of nano-hardness and micro-compression measurements for yield stress estimation journal March 2008
Ion-irradiation-induced damage in Fe–Cr alloys characterized by nanoindentation journal October 2011
Characterization and comparative analysis of the tensile properties of five tempered martensitic steels and an oxide dispersion strengthened ferritic alloy irradiated at ≈295 °C to ≈6.5 dpa journal January 2016
Micropillar compression study of the influence of size and internal boundary on the strength of HT9 tempered martensitic steel journal May 2018
FIB damage of Cu and possible consequences for miniaturized mechanical tests journal June 2007
Micro-tension behaviour of lath martensite structures of carbon steel journal January 2013
Molecular dynamics study on threshold displacement energies in Fe-Cr alloys journal March 2018
Plasticity in small-sized metallic systems: Intrinsic versus extrinsic size effect journal August 2011
Small-scale mechanical testing on nuclear materials: bridging the experimental length-scale gap journal January 2018
Intrinsic-extrinsic size effect relationship for micromechanical tests journal March 2019
Effects of focused ion beam milling on the nanomechanical behavior of a molybdenum-alloy single crystal journal September 2007
Relaxation volumes of microscopic and mesoscopic irradiation-induced defects in tungsten journal August 2019
Effect of dose on irradiation-induced loop density and Burgers vector in ion-irradiated ferritic/martensitic steel HT9 journal June 2018
Tensile Properties of Martensitic Stainless Steels at Elevated Temperatures journal May 2005
A nanoindentation study on grain-boundary contributions to strengthening and aging degradation mechanisms in advanced 12 Cr ferritic steel journal January 2007
Small scale mechanical testing of irradiated materials journal April 2015
Irradiation Effects of ht-9 Martensitic Steel journal June 2013

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