Fracture toughness of ferritic steel in the ductile-to-brittle transition zone is scattered and probabilistic owing to embrittlement. Use of master curve along with the reference temperature (T0) adopted in ASTM E-1921 is widely accepted for characterization of this embrittlement. Reference temperature is a measure of embrittlement in the temperature scale. Factors affecting fracture toughness like geometry and loading rate are expected to influence the reference temperature. In the present study, the role of the loading rate on the reference temperature for 20MnMoNi55 steel is assessed experimentally using compact tension C(T) and three-point bend (TPB) specimens. Finite element simulation of tests at different loading rates and cryogenic temperature are carried out using a suitable viscoplastic material model that incorporates flow characteristics of the material for varying displacement rates and cryogenic temperatures. Results from simulation studies are compared with experimental ones.
KimSHParkYWLeeJH, et al. Estimation of fracture toughness in the transition region using CVN data. In: 15th international conference on structural mechanics in reactor technology (SMiRT 15), Seoul, Korea, 15–20 August 1999.
2.
Application of master curve method fracture toughness methodology for ferritic steel. EPRI Technical Report, 1998.
3.
KimSHParkYWKangSS, et al.
Estimation of fracture toughness transition curves of RPV steels from Charpy impact test data. Nucl Eng Des2002;
212: 49–57.
4.
WallinK.Master curve analysis of the “Euro” fracture toughness dataset. Eng Fract Mech2002;
69: 451–481.
5.
WallinK.Use of the Master Curve methodology for real three-dimensional cracks. Nucl Eng Des2007;
237: 1388–1394.
6.
BhowmikSChattopadhyayABoseT, et al.
Estimation of fracture toughness of 20MnMoNi55 steel in the ductile to brittle transition region using master curve method. Nucl Eng Des2011;
241: 2831–2838.
7.
International Atomic Energy Agency. Master curve approach to monitor fracture toughness of reactor pressure vessels in nuclear power plants. IAEA-TECDOC-1631, Vienna, 2009.
PaulSAcharyyaSSahooP, et al. Rate dependence of dynamic fracture toughness of 20MnMoNi55 low-carbon steel using two methods on instrumented drop weight test of PCVN. In: Structural integrity assessment: proceedings of ICONS 2018, Chennai, India, 31 July 2020, pp. 555–567.
10.
FreundLB.Dynamic fracture mechanics.
Cambridge:
Cambridge University Press, 1990.
11.
WallinK. Summary of the IAEA/CRP3 fracture mechanical results. In: Proceedings IAEA specialists meeting, IAEA working material, Espoo, Finland, 1999.
12.
SreenivasanPR.Inverse of Wallin’s relation for the effect of strain rate on the ASTM E-1921 reference temperature and its application to reference temperature estimation from Charpy tests. Nucl Eng Des2011;
241: 67–81.
13.
PaulSAcharyyaSKSahooP, et al. Transition reference temperature for 20MnMoNi55 RPV steel at different loading rates. In: SahooPDavimJP (eds) Advances in materials, mechanical and industrial engineering. INCOM 2018. Lecture notes on multidisciplinary industrial engineering.
Cham:
Springer, 2019, pp. 107–128.
14.
PaulSDeyPBhattacharjeeS, et al.
Phenomenological modelling of flow behaviour of 20MnMoNi55 reactor pressure vessel steel at cryogenic temperature with different strain rates. Defence Technol2019;
15: 326–337.
15.
KhanASLiangR.Behaviours of three BCC metal over a wide range of strain rates and temperatures: experiments and modelling. Int J Plast1999;
15: 1089–1109.
16.
PaulSK.Predicting the flow behaviour of metals under different strain rate and temperature through phenomenological modelling. Comput Mater Sci2012;
65: 91–99.
17.
MolinariA.RavichandranG.Constitutive modeling of high-strain-rate displacement in metals based on the evolution of an effective microstructural length. Mech Mater2005;
37: 737–752.
18.
JohnsonGRCookWH. A constitutive model and data for metals subjected to large strains, high strain rates and high temperatures. In: The 7th international symposium on ballistic, 1983, p. 541.
19.
RusinekAZaeraRKlepaczkoJR.Constitutive relations in 3-D for a wide range of strain rates and temperatures - application to mild steels. Int J Solids Struct2007;
44: 5611–5634.
20.
ZerilliFJArmstrongRW.Dislocation-mechanics-based constitutive relations for material dynamics calculations. J Appl Phys1987;
61: 1816–1825.
21.
DeySDeyPDattaS.Design of novel age-hardenable aluminium alloy using evolutionary computation. J Alloys Compnd2017;
704: 373–381.
22.
ASTM E8/E8M-16a. Standard test methods for tension testing of metallic materials. West Conshohocken, PA: ASTM International, 2016.
23.
ASTM E647-15e1. Standard test method for measurement of fatigue crack growth rates. West Conshohocken, PA: ASTM International, 2015.
24.
ASTM E1820-18ae1. Standard test method for measurement of fracture toughness. West Conshohocken, PA: ASTM International, 2018.
25.
ASTM E1921-19b. Standard test method for determination of reference temperature, to, for ferritic steels in the transition range. West Conshohocken, PA: ASTM International, 2019.
26.
BhattacharyyaKAcharyyaSKChattopadhyayJ, et al.
Study of constraint effect on reference temperature (T0) of reactor pressure vessel material (20MnMoNi55 steel) in the ductile to brittle transition region. Procedia Eng2014;
86: 264–271.
