Establishing the Correlation Between Charpy Impact Energies for Different Sized Specimens of Modern Pipeline Steels

2014 ◽  
Author(s):  
Aida Nonn ◽  
Holger Brauer
Keyword(s):  
Impact Energy ◽  
Fracture Behavior ◽  
Damage Mechanics ◽  
Damage Model ◽  
Charpy Impact ◽  
Model Parameters ◽  
Principal Stresses ◽  
Gtn Model ◽  
The One ◽  
The Impact

The safety assessment of flawed pressurized pipes requires the knowledge of toughness properties which are usually provided in terms of impact energy from standard full-sized CVN notch specimens. For pipes with wall thickness less than 10mm different Charpy standards allow for the application of sub-sized specimens. However, it is still not fully clear how the impact energy from sub-sized specimens can be used to evaluate the fracture resistance of the pipes and how this energy correlates to the one from the full-sized specimen. Although different empirical correlations between sub-sized and full-sized specimens exist in the literature their validity is questionable since they are based on the results for older generation of steels. In the recent years the application of damage mechanics models has been promoted to assess the fracture behavior and deformation capacity of pipelines. The main advantage of these models can be found in their capability to link the damage evolution and the underlying stress/strain condition. In this paper damage mechanics approach is applied to describe fracture behavior of X65 pipeline material. Within the damage mechanics approach, Gurson-Tvergaard-Needleman (GTN) model is considered to be adequate for the simulation of ductile fracture. For brittle fracture, GTN model is extended by a propagation criterion which examines if the cleavage fracture stress is reached by the maximal principal stresses. The model parameters are calibrated and verified by means of load-displacement curves obtained from instrumented impact tests on different sized CVN specimens. This damage model is subsequently employed to simulate ductile-brittle transition behavior.

Investigation on Impact Energy of S30403 Austenitic Stainless Steel at Different Temperatures

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Zhiwei Chen ◽  
Caifu Qian ◽  
Guoyi Yang ◽  
Xiang Li
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cross Section ◽  
Test Temperature ◽  
Impact Energy ◽  
Welded Joint ◽  
Charpy Impact ◽  
Base Plate ◽  
Charpy Impact Energy ◽  
The Impact

In this paper, a series of impact tests on S30403 austenitic stainless steel at 20/−196/−269 °C were performed to determine the effects of cryogenic temperatures on the material properties. Both base plate and welded joint including weld and heat-affected zone were tested to obtain the Charpy impact energy KV2 and lateral expansion rate at the cross section. It was found that when the test temperature decreased from 20 °C to −196 °C or −269 °C, both the Charpy impact energy KV2 at the base plate and welded joint decreased drastically. Specifically, the impact energy KV2 decreased by 20% at the base plate and decreased by 54% at the welded joint from 20 °C to −196 °C, but the impact energy of base plate and welded joint did not decrease, even increased when test temperature decreased from −196 °C to −269 °C. Either at 20 °C or −196 °C, the impact energy KV2 with 5 × 10 × 55 mm3 specimens was about 0.53 times that of the 7.5 × 10 × 55 mm3 specimens, much lower than 2/3, the ratio of two specimens’ cross section areas.

Evaluations of Ductile and Cleavage Fracture Using Coupled GTN and Beremin Model in API X70 Pipelines Steel

2019 ◽  
Author(s):  
Youn-Young Jang ◽  
Ji-Hee Moon ◽  
Nam-Su Huh ◽  
Ki-Seok Kim ◽  
Woo-Yeon Cho ◽  
...  
Keyword(s):  
Ductile Fracture ◽  
Cleavage Fracture ◽  
Fracture Behavior ◽  
Pipeline Steel ◽  
Model Parameters ◽  
Experiment Data ◽  
Local Approach ◽  
Gtn Model ◽  
Weibull Parameters ◽  
X70 Pipeline Steel

Abstract This paper is aimed to characterize ductile and cleavage fracture behavior of API X70 pipeline steel and investigate applicability of a micro-damage mechanics model to simulate static and dynamic crack propagation of single-edge notched tension (SENT) and drop-weight tear test (DWTT) specimens, as well as a local approach to describe cleavage fracture behavior. Gurson-Tvergaard-Needleman (GTN) model was applied to simulate ductile fracture behavior of SENT and DWTT specimens, where GTN model has been widely known for well-established model to characterize micro-damage process of void nucleation, growth and coalescence. As for a local approach, Beremin model was considered to estimate probability of cleavage fracture. In this regard, this study was especially focused on abnormal fracture appearance of DWTT specimen. In the present study, firstly, experiment data from tensile specimen test was used to obtain plastic flow curve (i.e. stress and strain curve). And load-CMOD and J-integral/CTOD resistance curves obtained from SENT test were used to characterize static ductile fracture and calibrate GTN model parameters for X70 pipeline steel. And the calibrated GTN model parameters were verified by comparing experiment data from DWTT test such as load-displacement and crack length-time curves with those from FE analysis. To accommodate dynamic effect on material properties, rate-dependent stress-strain curves were considered in FE analyses. To describe cleavage fracture, the Weibull stress was calculated from FE analyses of DWTT and Weibull parameters were calibrated by comparing with probability distribution of cleavage fracture from experiment data of DWTT specimen. Using Weibull parameters, the whole of cleavage fracture probability can be estimated as ductile shear area of DWTT specimen increases.

Elastic–plastic-damage model of nano-indentation of the ion-irradiated 6061 aluminium alloy

2020 ◽  
Vol 29 (8) ◽  
pp. 1271-1305
Author(s):  
A Ustrzycka ◽  
B Skoczeń ◽  
M Nowak ◽  
Ł Kurpaska ◽  
E Wyszkowska ◽  
...  
Keyword(s):  
Damage Evolution ◽  
Damage Mechanics ◽  
Ion Irradiation ◽  
Damage Model ◽  
Indentation Test ◽  
Gtn Model ◽  
Damage Level ◽  
Nano Indentation ◽  
Wide Range ◽  
Radiation Induced

The paper presents experimental and numerical characterization of damage evolution for ion-irradiated materials subjected to plastic deformation during nano-indentation. Ion irradiation technique belongs to the methods where creation of radiation-induced defects is controlled with a high accuracy (including both, concentration and depth distribution control), and allows to obtain materials having a wide range of damage level, usually expressed in terms of displacements per atom (dpa) scale. Ion affected layers are usually thin, typically less than 1 micrometer thick. Such a low thickness requires to use nano-indentation technique to measure the mechanical properties of the irradiated layers. The He or Ar ion penetration depth reaches approximately 150 nm, which is sufficient to perform several loading-partial-unloading cycles at increasing forces. Damage evolution is reflected by the force-displacement diagram, that is backed by the stress–strain relation including damage. In this work the following approach is applied: dpa is obtained from physics (irradiation mechanisms), afterwards, the radiation-induced damage is defined in the framework of continuum damage mechanics to solve the problem of further evolution of damage fields under mechanical loads. The nature of radiation-induced damage is close to porosity because of formation of clusters of vacancies. The new mathematical relation between radiation damage (dpa) and porosity parameter is proposed. Deformation process experienced by the ion irradiated materials during the nano-indentation test is then numerically simulated by using extended Gurson–Tvergaard–Needleman (GTN) model, that accounts for the damage effects. The corresponding numerical results are validated by means of the experimental measurements. It turns out, that the GTN model quite successfully reflects closure of voids, and increase of material density during the nano-indentation.

Crack Initiation and Growth in Bimetallic Girth Welds

2014 ◽  
Author(s):  
Antonio Carlucci ◽  
Nicola Bonora ◽  
Andrew Ruggiero ◽  
Gianluca Iannitti ◽  
Domenico Gentile
Keyword(s):  
Crack Initiation ◽  
Damage Mechanics ◽  
Damage Model ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Model Parameters ◽  
Ductile Crack ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Girth Welds

Bimetallic girth welds are characteristics of clad pipe technology. When dealing with propagation issues, fracture mechanics concepts usually are no longer applicable as a result of the extensive and non-homogeneous plastic deformation along bi-material interface that occur at the crack tip even below design allowables. In this study, ductile crack initiation and propagation in bi-material girth welds was investigated using a Continuum Damage Mechanics (CDM) model proposed by Bonora [1]. For the base, weld and clad metal, ductile damage model parameters have been determined by means of inverse calibration technique using fracture data obtained on smooth and round notched tensile bar specimens. Firstly, the damage model was validated predicting ductile crack growth occurring in single end notch (SEN(T)) geometry sample comparing the applied load vs crack mouth opening displacement with experimental measurements. Successively, the model was used to investigate ductile crack initiation and propagation for under clad circumferential weld crack under remote tension.

Microstructure and Toughness of Weld CGHAZ Under Different Heat Input for X90 High Strength Pipeline Steel

2016 ◽  
Author(s):  
Liuqing Yang ◽  
Yongli Sui ◽  
PeiPei Xia ◽  
Die Yang ◽  
Yongqing Zhang
Keyword(s):  
Impact Toughness ◽  
Impact Energy ◽  
Heat Input ◽  
Pipeline Steel ◽  
Charpy Impact ◽  
Optical Microscope ◽  
Granular Bainite ◽  
Alloy Content ◽  
Welding Heat Input ◽  
The Impact

Two kinds of industry trial X90 pipeline steel which had different chemical composition were chosen as experimental materials, and the grain coarsening, microstructure evolution characteristics and the variation rules of low-temperature impact toughness in weld CGHAZ of this two steel under different welding heat input were studied by physical thermal simulation technology, SEM, optical microscope and Charpy impact test. The results show that microstructure in weld CGHAZ of 1# steel is mainly bainite ferrite (BF) and most of the M/A constituents are blocky or short rod-like; the grains of 2# steel are coarse and there is much granular bainite (GB), meanwhile M/A constituents become coarse and their morphology is changing from block to elongated laths; alloy content of X90 pipeline steel under different welding heat input has great effect on the grain size of original austenite, and when heat input is lower than 2.0KJ/mm, Charpy impact toughness in CGHAZ of lower alloy content pipeline steel is good; as heat input increases, impact toughness in CGHAZ of 1# steel is on the rise, and it is high (between 260J and 300J) when heat input is between 2.0KJ/mm and 2.5KJ/mm and the scatter of impact energy is small; impact toughness of 2# steel decreases gradually and the impact energy has obvious variability.

scholarly journals Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process

2017 ◽  
Vol 62 (2) ◽  
pp. 1341-1346 ◽  
Author(s):  
K.-A. Lee ◽  
Y.-K. Kim ◽  
J.-H. Yu ◽  
S.-H. Park ◽  
M.-C. Kim
Keyword(s):  
Heat Treatment ◽  
Impact Toughness ◽  
Selective Laser Melting ◽  
Impact Energy ◽  
Charpy Impact ◽  
Melting Process ◽  
Laser Melting ◽  
Average Impact ◽  
Before And After ◽  
The Impact

AbstractThis study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs) on microstructure and impact toughness of the material. Initial microstructural observation identified prior-βgrain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment,αandβphase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.

scholarly journals Application of a GTN Damage Model Predicting the Fracture of 5052-O Aluminum Alloy High-Speed Electromagnetic Impaction

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 761 ◽  
Author(s):  
Fei Feng ◽  
Jianjun Li ◽  
Peng Yuan ◽  
Qixian Zhang ◽  
Pan Huang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
High Speed ◽  
Fracture Behavior ◽  
Volume Fraction ◽  
Damage Model ◽  
Weight Ratio ◽  
Model Parameters ◽  
Highly Nonlinear ◽  
Gtn Damage Model ◽  
Increasing Demand

An increasing demand exists within the automotive industry to utilize aluminum alloy sheets because of their excellent strength-weight ratio and low emissions, which can improve fuel economy and reduce environmental pollution. High-speed automobile impactions are complicated and highly nonlinear deformation processes. Thus, in this paper, a Gurson-Tvergaard-Needleman (GTN) damage model is used to describe the damage behavior of high-speed electromagnetic impaction to predict the fracture behavior of 5052-O aluminum alloy under high-speed impaction. The parameters of the GTN damage model are obtained based on high-speed electromagnetic forming experiments via scanning electron microscopy. The high-speed electromagnetic impaction behavior process is analyzed according to the obtained GTN model parameters. The shape of the high-speed electromagnetic impaction in the numerical simulations agrees with the experimental results. The analysis of the plastic strain and void volume fraction distributions are analyzed during the process of high-speed impact, which indicates the validity of using the GTN damage model to describe or predict the fracture behavior of high-speed electromagnetic impaction.

Impact Toughness of 0.3 Mass% Carbon Tempered Martensitic Steels Evaluated by Instrumented Charpy Test

2014 ◽  
Vol 783-786 ◽  
pp. 1033-1038
Author(s):  
Shigeto Takebayashi ◽  
Kohsaku Ushioda ◽  
Naoki Yoshinaga ◽  
Shigenobu Ogata
Keyword(s):  
Impact Toughness ◽  
Temperature Dependence ◽  
Impact Energy ◽  
Charpy Impact ◽  
Waveform Analysis ◽  
Charpy Impact Energy ◽  
Martensitic Steels ◽  
Tempering Temperature ◽  
Wide Range ◽  
The Impact

The effect of tempering temperature on the impact toughness of 0.3 mass% carbon martensitic steels with prior austenite grain (PAG) size of about 6 μm and 30 μm were investigated. Instrumented Charpy impact test (ICIT) method was used to evaluate the impact toughness. The tempering temperature of 723K gives the largest difference in the Charpy impact energy at room temperature (RT) between the specimens with two different PAG sizes. Investigation of the test temperature dependence of Charpy impact energy in the 723K tempered steels shows a steep transition at around 200 K for the 6 μm PAG specimen, while it shows a continuous slow transition in a wide range of temperature for the 60 μm PAG specimen. ICIT waveform analysis shows that the fracture propagation energy in stead of the fracture initiation energy mainly controls the temperature dependence of the impact energy. The carbide size distribution in these two specimens was investigated by SEM and TEM. The 60 μm PAG specimen shows the distribution of coarser carbides than does the 6 μm PAG specimen, which seems to be the main reason for the observed difference between them in the Charpy impact energy and the other properties of impact fracture.

COUPLED ANALYSIS OF DAMAGE IN MULTIPHASE MEDIA

2012 ◽  
Vol 04 (02) ◽  
pp. 1250008
Author(s):  
MARZIYEH FATHALIKHANI ◽  
BEHROUZ GATMIRI
Keyword(s):  
Damage Model ◽  
Coupled Analysis ◽  
Model Parameters ◽  
State Variables ◽  
Damage Development ◽  
Water Conductivity ◽  
Internal Length ◽  
Finite Element Program ◽  
Independent State ◽  
The Impact

In this paper, the theoretical framework of a coupled thermo-hydro-mechanical damage model dedicated to non-isothermal unsaturated porous media is presented. The damage variable is a second-order tensor, and the model has been formulated in independent state variables. The approach combines thermodynamic and micromechanical theories. The behavior laws have been derived from a postulated expression of Helmholtz free energy. The damaged rigidities have been computed by applying the Principle of Equivalent Elastic Energy (PEEE). Internal length parameters have been introduced in the expressions of liquid water conductivity, to account for cracking effects on fluid flows. Damage has been assumed to have an isotropic influence on air and heat flows, through the inelastic component of volumetric strains. The damage model has been implemented in θ-Stock Finite Element program. Some numerical studies are conducted to the impact of the thermal and mechanical loading on the evaluation of response of the unsaturated bentonite, and investigation of model parameters effect on damage development.

Glass Bottle Fracture Behavior by Underwater Shock-Wave - Effect of Micro-Bubble on the Fracture Behavior -

2018 ◽  
Vol 774 ◽  
pp. 303-306
Author(s):  
Yoshifumi Ohbuchi ◽  
Sota Sugahara ◽  
Shigeru Tanaka ◽  
Shinichi Enoki ◽  
Genj Hotta ◽  
...  
Keyword(s):  
Shock Wave ◽  
Fracture Behavior ◽  
Experimental Result ◽  
Glass Bottle ◽  
Underwater Shock Wave ◽  
Small Glass ◽  
Micro Bubble ◽  
Underwater Shock ◽  
The One ◽  
The Impact

In order to promote the recycling of the one way glass bottles, the impact fracture by using the pulse power underwater shock-wave with micro bubble was examined. It is reported that the pressure of underwater shock-wave with micro-bubble increases. From the experimental result, the glass bottle‘s crushed experiment was executed in the water with micro-bubble. As a result, the small glass fragments (Cullet) increased and it was shown that the micro-bubble in the water promoted the bottle fracture.

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