Exploratory evaluation of the T0 reference temperature for a high strength martensitic steel using the master curve approach

2021 ◽  
Author(s):  
Vinicius Mota da Cruz Gomes ◽  
Vitor Scarabeli Barbosa ◽  
Claudio Ruggieri
Keyword(s):  
Master Curve ◽  
Martensitic Steel ◽  
High Strength ◽  
Reference Temperature

Fracture Toughness Testing Using Non-Standard PCVN Specimens: Experiments and Specimen Geometry Effects on T0 Reference Temperature

2018 ◽  
Author(s):  
Vitor Scarabeli Barbosa ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Cleavage Fracture ◽  
Master Curve ◽  
High Strength ◽  
Potential Effect ◽  
Reference Temperature ◽  
Fracture Toughness Testing ◽  
Toughness Testing ◽  
Additional Support

This work addresses an experimental investigation on the cleavage fracture behavior of a high strength, low alloy structural steel using non-standard PCVN specimens. The primary purpose is to investigate the effects of increased specimen span on experimentally measured fracture toughness values and implications for the characterization of the temperature dependence of toughness based on the Master Curve methodology. Fracture toughness testing conducted on various PCVN geometries with increased specimen span extracted from an A572 Grade 50 steel plate provides the cleavage fracture resistance data in terms of the J-integral at cleavage instability, Jc. The experimental results show a potential effect of specimen span on Jc-values which can help mitigating the effects of constraint loss often observed in smaller fracture specimens. An exploratory application to determine the reference temperature, T0, derived from the Master Curve methodology also provides additional support for using non-standard bend specimens in routine fracture applications.

scholarly journals Hot Deformation Behavior and Dynamic Recrystallization of Ultra High Strength Steel

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1239
Author(s):  
Liping Zhong ◽  
Bo Wang ◽  
Chundong Hu ◽  
Jieyu Zhang ◽  
Yu Yao
Keyword(s):  
Martensitic Steel ◽  
High Strength ◽  
Experimental Results ◽  
Hot Deformation Behavior ◽  
Thermal Compression ◽  
Forging Process ◽  
Finite Element Software ◽  
Ultra High Strength Steel ◽  
Recrystallized Grain Size ◽  
Deform 3D

In this paper, in order to improve the microstructure uniformity of an ultra-high strength martensitic steel with a strength greater than 2500 MPa developed by multi-directional forging in the laboratory, a single-pass hot compression experiment with the strain rate of 0.01 to 1 s−1 and a temperature of 800 to 1150 °C was conducted. Based on the experimental data, the material parameters were determined, the constitutive model considering the influence of work hardening, the recrystallization softening on the dislocation density, and the recrystallized grain size model were established. After introducing the model into the finite element software DEFORM-3D, the thermal compression experiment was simulated, and the results were consistent with the experimental results. The rule for obtaining forging stock with a uniform and refinement microstructure was acquired by comparing the simulation and the experimental results, which are helpful to formulate an appropriate forging process.

Fracture toughness master-curve analysis of the tempered martensitic steel Eurofer97

2009 ◽  
Vol 386-388 ◽  
pp. 323-327 ◽  
Author(s):  
Pablo Mueller ◽  
P. Spätig ◽  
R. Bonadé ◽  
G.R. Odette ◽  
D. Gragg
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Martensitic Steel ◽  
Curve Analysis

A new effect of retained austenite on ductility enhancement in high-strength quenching–partitioning–tempering martensitic steel

2011 ◽  
Vol 528 (29-30) ◽  
pp. 8486-8491 ◽  
Author(s):  
Ke Zhang ◽  
Meihan Zhang ◽  
Zhenghong Guo ◽  
Nailu Chen ◽  
Yonghua Rong
Keyword(s):  
Retained Austenite ◽  
Martensitic Steel ◽  
High Strength

International Round Robin Test on Master Curve Reference Temperature Evaluation Utilizing Miniature C(T) Specimen

2014 ◽  
pp. 1-17 ◽  
Author(s):  
Yamamoto Masato ◽  
Onizawa Kunio ◽  
Yoshimoto Kentaro ◽  
Ogawa Takuya ◽  
Mabuchi Yasuhiro ◽  
...  
Keyword(s):  
Master Curve ◽  
Round Robin ◽  
Reference Temperature ◽  
Round Robin Test ◽  
International Round

Investigation of the Beltline Welding Seam and Base Metal of the Greifswald WWER-440 Unit 1 Reactor Pressure Vessel

2009 ◽  
Author(s):  
Jan Schuhknecht ◽  
Hans-Werner Viehrig ◽  
Udo Rindelhardt
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Pressure Vessel ◽  
Master Curve ◽  
Reactor Pressure Vessel ◽  
Reference Temperature ◽  
Metal Ring ◽  
Welding Seam ◽  
Root Region ◽  
Reactor Pressure

The investigation of reactor pressure vessel (RPV) materials from decommissioned NPPs offers the unique opportunity to scrutinize the irradiation behaviour under real conditions. Material samples taken from the RPV wall enable a comprehensive material characterisation. The paper describes the investigation of trepans taken from the decommissioned WWER-440 first generation RPVs of the Greifswald NPP. Those RPVs represent different material conditions such as irradiated (I), irradiated and recovery annealed (IA) and irradiated, recovery annealed and re-irradiated (IAI). The working program is focussed on the characterisation of the RPV steels (base and weld metal) through the RPV wall. The key part of the testing is aimed at the determination of the reference temperature T0 following the ASTM Test Standard E1921-05 to determine the fracture toughness of the RPV steel in different thickness locations. In a first step the trepans taken from the RPV Greifswald Unit 1 containing the X-butt multilayer submerged welding seam and from base metal ring 0.3.1 both located in the beltline region were investigated. Unit 1 represents the IAI condition. It is shown that the Master Curve approach as adopted in ASTM E1921 is applicable to the investigated original WWER-440 weld metal. The evaluated T0 varies through the thickness of the welding seam. The lowest T0 value was measured in the root region of the welding seam representing a uniform fine grain ferritic structure. Beyond the welding root T0 shows a wavelike behaviour. The highest T0 of the weld seam was not measured at the inner wall surface. This is important for the assessment of ductile-to-brittle temperatures measured on sub size Charpy specimens made of weld metal compact samples removed from the inner RPV wall. Our findings imply that these samples do not represent the most conservative condition. Nevertheless, the Charpy transition temperature TT41J estimated with results of sub size specimens after the recovery annealing was confirmed by the testing of standard Charpy V-notch specimens. The evaluated Charpy-V TT41J shows a better accordance with the irradiation fluence along the wall thickness than the Master Curve reference temperature T0. The evaluated T0 from the trepan of base metal ring 0.3.1 varies through the thickness of the RPV wall. T0 increases from −120°C at the inner surface to −104°C at a distance of 33 mm from it and again to −115°C at the outer RPV wall. The KJc values generally follow the course of the MC, although the scatter is large. The re-embrittlement during 2 campaigns operation can be assumed to be low for the weld and base metal.

A Combined Model Approach for Estimating T0

2019 ◽  
Author(s):  
Marjorie Erickson
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Reference Temperature ◽  
Initiation Toughness ◽  
Correlation Model ◽  
Combined Model ◽  
Best Estimate ◽  
Curve Model ◽  
Asme Code ◽  
Model Approach

Abstract The current best-estimate model describing the fracture toughness of ferritic steels is the Master Curve methodology standardized in ASTM E1921. Shortly following standardization by ASTM, efforts were undertaken to incorporate this best-estimate model into the framework of the ASME Code to reduce the conservatisms resulting from use of a reference temperature based on the nil-ductility temperature (RTNDT) to index the plane strain fracture initiation toughness (KIc). The reference temperature RTT0, which is based on the ASTM E1921-defined T0 value, was introduced in ASME Code Cases N-629 (replaced by Code Case N-851) and N-631 to replace RTNDT for indexing the ASME KIc curve. Efforts are continuing within the ASME Code to implement direct use of the Master Curve model; using the T0 reference temperature to index an elastic-plastic, KJc fracture toughness curve. Transitioning to a direct T0-based fracture toughness assessment methodology requires the availability of T0 estimates for all materials to be assessed. The historical Charpy and NDT-based regulatory approach to characterizing toughness for reactor pressure vessel (RPV) steels results in a lack of T0 values for a large population of the US nuclear fleet. The expense of the fracture toughness testing required to estimate a valid T0 value makes it unlikely that T0 will ever be widely available. Since direct implementation of best-estimate, fracture toughness models in codes and regulatory actions requires an estimate of T0 for all materials of interest it is necessary to develop an alternative means of estimating T0. A project has been undertaken to develop a combined model approach to estimating T0 from data that may include limited elastic-plastic fracture toughness KJc, Charpy, tensile, ductile initiation toughness, arrest toughness, and/or nil-ductility temperature data. Using correlations between these properties and T0 a methodology for combining estimates of T0 from several sources of data was developed. T0 estimates obtained independently from the Master Curve model, the Simple T28J correlation model, and a more complex Charpy correlation model were combined using the Mixture Probability Density Function (PDF) method to provide a single estimate for T0. Using this method, the individual T0 estimates were combined using weighting factors that accounted for sample size and individual model accuracy to optimize the accuracy and precision of the combined T0 estimate. Combining weighted estimates of T0 from several sources of data was found to provide a more refined estimate of T0 than could be obtained from any of the models alone.

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