Evaluation of Fracture Initiation Energy in API X65 Pipeline Steel

2008 ◽  
Author(s):  
Sayyed H. Hashemi ◽  
Mohammad R. Jalali
Keyword(s):  
Fracture Energy ◽  
Pipeline Steel ◽  
Fracture Initiation ◽  
Pipe Material ◽  
Correction Factors ◽  
Steel Mill ◽  
Initiation Energy ◽  
Seam Weld ◽  
Energy Consuming ◽  
The Impact

In this paper, energy absorption characteristics of spiral welded gas pipeline steel are investigated under impact loading. Emphasise is given to energy consuming processes before fracture propagation in tested linepipe steel. The API X65 grade pipe was produced (by Sadid Pipe and Equipment Company) from thermo-mechanical controlled process (TMCP) coils supplied by a Korean steel mill. To measure material impact toughness, an instrumented Charpy machine was used. Experiments were conducted at room temperature on different sets of standard full size Charpy V-notched specimens taken from the pipe material, seam weld and heat affected zone. The instrumented Charpy machine was able to capture the load history in full during the fracture process of the test specimens resulting in a smooth load-time response. This eliminated the need for filtering used in similar test techniques. From the recorded test data the hammer displacement, impact velocity and fracture energy were numerically calculated. The numerical results showed good agreement between the instrumentation data and those read from dial indicator. From fracture energy plots it was found that the maximum and minimum fracture energy was associated with the pipe material and seam weld, respectively. In all test samples, a significant amount of energy was consumed in non-fracture related processes including indentation at the support anvils and at the impact point, bending of test specimen and crack initiation. From this finding, correction factors were suggested to account for considerable energy level of non-fracture related processes. This energy had been ignored apparently in conventional pipeline failure models calibrated in the past on low toughness pipe materials in which fracture initiation energy was negligible. The paper concluded with a comparison of suggested correction factors with those obtained by full-scale burst experiments on tough pipeline steels.

Measurement and Analysis of Impact Test Data for X100 Pipeline Steel

2006 ◽  
Vol 3-4 ◽  
pp. 369-376 ◽  
Author(s):  
S.H. Hashemi ◽  
I.C. Howard ◽  
J.R. Yates ◽  
R.M. Andrews
Keyword(s):  
Fracture Energy ◽  
Test Data ◽  
Impact Test ◽  
Pipeline Steel ◽  
Charpy Impact ◽  
Impact Testing ◽  
High Grade ◽  
Initiation Energy ◽  
Pipeline Steels ◽  
The Impact

Charpy upper shelf energy is widely used as a fracture controlling parameter to estimate the crack arrest/propagation performance of gas transportation pipeline steels. The measurement of this fracture criterion particularly for modern steels and its apportion into different components, i.e. fracture and non-related fracture energy, are of great importance for pipeline engineers. This paper presents the results of instrumented Charpy impact experiments on high-grade pipeline steel of grade X100. First, the instrumentation technique including the design and implementation of a strain gauge load-cell and the details of the data-recording scheme are reviewed. Next, the experimental data obtained from the Charpy impact machine so instrumented are presented and discussed. These include the test data from full and sub-sized Charpy V-notched specimens. The instrumented Charpy machine was able to capture the load history in full during the fracture process of the test specimens resulting in a smooth load-time response. This eliminated the need for filtering used in similar test techniques. From the recorded test data the hammer displacement, impact velocity and fracture energy were numerically calculated. The results showed that there was a significant drop in hammer velocity during the impact event. This resulted in a change in the fracture mode from dynamic to quasi-static which was more appreciable for full-size Charpy test samples. As a result, sub-sized specimens might be preferable for impact testing of this steel in order to guarantee the conditions of dynamic crack propagation in the specimen ligament. Accurate analysis of the instrumented impact test data showed that the ratio of crack initiation energy to propagation energy was around 30% for the X100 steel. It can be concluded that in impact testing of high-grade pipeline steel a significant portion of overall fracture energy is consumed in non-related fracture processes. This high fracture initiation energy should be accounted for if the current failure models are going to be used for toughness assessment of highstrength low-alloy gas pipeline steels.

Experimental Study of Charpy Impact Characteristics of High-Strength Spiral Welded Gas Pipeline

2006 ◽  
Author(s):  
Sayyed H. Hashemi ◽  
Mohammad R. Jalali
Keyword(s):  
Fracture Energy ◽  
Test Data ◽  
Impact Test ◽  
Charpy Impact ◽  
High Strength ◽  
Gas Pipeline ◽  
Pipe Material ◽  
Pipeline Steels ◽  
Seam Weld ◽  
The Impact

Charpy upper shelf energy is widely used as a fracture controlling parameter to estimate the crack arrest/propagation performance of gas transportation pipeline steels. The measurement of this fracture criterion particularly for modern steels and its apportion into different components (i.e. fracture and non-related fracture energy) are of great importance for pipeline engineers in order to transfer laboratory data from Charpy experiment to real structure. As the conventional Charpy impact test has only one output (i.e. the overall fracture energy) the instrumented test has been used to achieve full failure information from impact test samples. In this paper the results of instrumented Charpy impact experiments on high-strength spiral welded pipeline steel of grade API X70 are presented. First, the instrumentation technique including the design and implementation of a strain gauge load-cell and the details of the data-recording scheme are reviewed. Next, the experimental data obtained from the Charpy impact machine so instrumented are given. These include test data obtained at room temperature from different sets of standard full size Charpy V-notched specimens taken from the pipe material, seam weld and heat affected zone (HAZ). The instrumented Charpy machine was able to capture the load history in full during the fracture process of the test specimens resulting in a smooth load-time response. This eliminated the need for filtering used in similar test techniques. From the recorded test data the hammer displacement, impact velocity and fracture energy were numerically calculated. The numerical results showed good agreement between the instrumentation data and those read from dial indicator. From fracture energy plots it was found that the maximum and minimum fracture energy were associated with the pipe material and seam weld (in average), respectively. In all test samples a significant amount of energy was consumed in non-related fracture processes including crack initiation, bending and gross deformation of test specimen, and indentation at the support anvils and at the impact point. This non-related fracture energy should be accounted for if the current failure models are going to be used for toughness assessment of high-strength low-alloy gas pipeline steels.

Experimental Investigation of Charpy Impact Resistance in Rail Vehicle Steel Wheels

2006 ◽  
Author(s):  
A. Asadi Lari ◽  
S. H. Hashemi
Keyword(s):  
Fracture Energy ◽  
Test Data ◽  
Elastic Strain Energy ◽  
Charpy Impact ◽  
Fracture Initiation ◽  
Direct Result ◽  
Dynamic Crack ◽  
Rail Vehicle ◽  
The Impact ◽  
Total Fracture

In this research the Charpy impact properties of the two steel wheels of grade B2N and R7 were investigated. The dynamic toughness levels of test materials were measured experimentally according to the general recommendations of International Union of Railways (UIC) test standards. To do this, two sets of standard Charpy U-notch impact specimens were taken from the original rail vehicle steel wheels (made from B2N and R7) in their circumferential direction. As the conventional Charpy impact machine gives only one output (i.e., total fracture energy), an instrumented Charpy rig was used for conducting the impact experiments. This provided novel impact test data as well as full failure information (appeared for the first time in the literature for rail vehicle steel wheels). The obtained data included elastic strain energy, fracture initiation, and fracture propagation energy. All these parameters were calculated by double integration of load history captured by a high frequency digital oscilloscope during impact tests. The results showed that the impact toughness of both steel wheels was above the minimum toughness specified by the UIC leaflet. Detailed analysis of instrumented fracture test data showed that a significant portion of total measured Charpy energy (more than 75%) was consumed in fracture initiation and non-related fracture processes in each test material. This is a direct result of high strain-hardening capacity of B2N and R7 steel wheels and their characteristics, which allows the material to absorb high amounts of energy and to deform plastically before any fracture initiation. The total fracture energy of the R7 wheel steel was 160% higher than the B2N (21J against 13J), which was indicative of better dynamic crack resistance of R7 wheel material.

Estimation of Slant Tearing Energy for High-Grade Pipeline Steel From Instrumented Charpy Test Data and its Transferability to Large Structures

2006 ◽  
Author(s):  
Sayyed H. Hashemi ◽  
Ian C. Howard ◽  
John R. Yates ◽  
Robert M. Andrews ◽  
Alan M. Edwards
Keyword(s):  
Crack Initiation ◽  
Fracture Energy ◽  
Pipeline Steel ◽  
Crack Arrest ◽  
Correction Factors ◽  
Charpy Test ◽  
Pipeline Steels ◽  
Fracture Models ◽  
Slant Fracture ◽  
Tearing Energy

For several decades, the Charpy upper shelf energy has been used as a fracture controlling parameter to estimate the crack arrest/propagation performance of gas transportation pipeline steels. However, significant discrepancies have been observed between the results of full-scale burst experiments on modern pipeline steels and those predicted by Charpy-based fracture models. This indicates that fracture models calibrated in the past on lower-grade pipeline steels (Charpy toughness below about 100J) cannot be extrapolated beyond their calibration range to assess the fracture behaviour of higher-strength high-toughness steels. One reason for this is the high level of energy often required for crack initiation in these steels. Accordingly, in the short term different correction factors ranging from 1.4 to 2 have been proposed to refine these fracture prediction models. The use of alternative failure parameters like CTOA is currently under review. In this paper a novel experimental technique is given to apportion the upper shelf Charpy fracture energy into its different components, i.e. crack initiation energy and flat and slant tearing energy. The experimental data from instrumented Charpy tests on standard impact specimens made from an X100 grade pipeline steel is used to estimate crack initiation and propagation energy. The areas associated with flat tearing in the centre and slant shearing at the edges of the fracture surface of Charpy test specimens are estimated optically using a fine measurement grid with 0.5 mm spacing. The energy required for generating the flat and slant fracture areas is calculated by the use of associated multipliers, i.e. the specific flat and slant fracture energy (in terms of J/mm2). These are measured separately using flat and slant crack growth data from fracture tests on standard C(T) and modified DCB like specimens. The results showed that the Charpy energy from a test is dominated by non-crack propagation energies. Around 36% of the measured impact energy appeared to be associated with flat and slant tearing processes. As the latter is the important failure micro-mechanism in pipeline steel only that part of the overall Charpy shelf energy which is associated with slant shearing might be used to evaluate the crack growth resistance of modern steels. This suggests the possible use of correction factors for high toughness pipeline steels of the order of 1.7 to transfer the slant fracture energy measured on small-scale specimens to the real structures for predicting their crack arrest/propagation behaviour. The correction factor proposed here from the laboratory test programme agrees with those obtained from costly full-thickness burst experiments on similar class of pipeline steel.

scholarly journals A new approach to radon temporal correction factor based on active environmental monitoring devices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
T. Dicu ◽  
B. D. Burghele ◽  
M. Botoş ◽  
A. Cucoș ◽  
G. Dobrei ◽  
...  
Keyword(s):  
Radon Concentration ◽  
Residential Buildings ◽  
Indoor Radon ◽  
Smart Device ◽  
Correction Factors ◽  
Indoor Radon Concentration ◽  
Radon Measurements ◽  
The Impact ◽  
Monitoring Devices ◽  
Temporal Correction

AbstractThe present study aims to identify novel means of increasing the accuracy of the estimated annual indoor radon concentration based on the application of temporal correction factors to short-term radon measurements. The necessity of accurate and more reliable temporal correction factors is in high demand, in the present age of speed. In this sense, radon measurements were continuously carried out, using a newly developed smart device accompanied by CR-39 detectors, for one full year, in 71 residential buildings located in 5 Romanian cities. The coefficient of variation for the temporal correction factors calculated for combinations between the start month and the duration of the measurement presented a low value (less than 10%) for measurements longer than 7 months, while a variability close to 20% can be reached by measurements of up to 4 months. Results obtained by generalized estimating equations indicate that average temporal correction factors are positively associated with CO2 ratio, as well as the interaction between this parameter and the month in which the measurement took place. The impact of the indoor-outdoor temperature differences was statistically insignificant. The obtained results could represent a reference point in the elaboration of new strategies for calculating the temporal correction factors and, consequently, the reduction of the uncertainties related to the estimation of the annual indoor radon concentration.

Characterization of the fracture behaviour of X42 microalloyed pipeline steel

2015 ◽  
Vol 6 (5) ◽  
pp. 567-577
Author(s):  
Halil Ibrahim Ünal ◽  
Hakan Atapek ◽  
Baran Gürkan Beleli ◽  
Seyda Polat ◽  
Serap Gümüs ◽  
...  
Keyword(s):  
Fracture Behaviour ◽  
Pipeline Steel ◽  
Sheet Material ◽  
Sheet Steel ◽  
Grain Morphology ◽  
Tensile Fracture ◽  
Pipe Material ◽  
Content Type ◽  
Fracture Surfaces ◽  
Impact Tests

Purpose – The purpose of this paper is to investigate the fracture of grade X42 microalloyed steel used as pipe material after tensile test at room temperature and impact tests at 0, −20 and −40°C, respectively. Design/methodology/approach – In the first stage of the study, X42 steels in the form of sheet and pipe materials were selected and etched samples were characterized using light microscope. In the second stage, mechanical properties of steels were obtained by microhardness measurements, static tensile and impact tests and all the broken surfaces were examined by scanning electron microscope to determine the fracture type as a function of both microstructure and loading. Findings – The examinations revealed that: first, the sheet material had a typical ferritic-pearlitic matrix, second, the transverse section of the sheet steel exhibited a matrix consisting of polygonal ferrite-aligned pearlite colonies and the longitudinal one had elongated ferrite phase and pearlite colonies in the direction of rolling, third, ferrite and pearlite distribution was different from the sheet material due to multiaxial deformation in the pipe material, fourth, tensile fracture surfaces of the steels had typical dimple fracture induced by microvoid coalescence, fifth, impact fracture surfaces of the steels changed as a function of the test temperature and cleavage fracture mode of ferritic-pearlitic matrix became more dominant as the temperature decreased, and sixth, grain morphology had an effect on the fracture behavior of the steels. Originality/value – The paper explains the fracture behaviour of X42 microalloyed pipeline steel and its fractographical analysis.

Low Velocity Impact Resistance of CPVC Pipes Exposed to Natural Outdoor Weathering Conditions

2012 ◽  
Vol 445 ◽  
pp. 959-964
Author(s):  
Z. Khan ◽  
Necar Merah ◽  
A. Bazoune ◽  
S. Furquan
Keyword(s):  
Impact Resistance ◽  
Outdoor Exposure ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Pipe Material ◽  
Low Velocity ◽  
Impact Energies ◽  
The Impact ◽  
Impact Events ◽  
Outdoor Weathering

Low velocity drop weight impact testing of CPVC pipes was conducted on 160 mm long pipe sections obtained from 4-inch (100 mm) diameter schedule 80 pipes. Impact test were carried out for the base (as received) pipes and after their exposure to out door natural weathering conditions in Dhahran, Saudi Arabia. The results of the impact testing on the natural (outdoor exposure) broadly suggest that the natural outdoor exposures produce no change in the impact resistance of CPVC pipe material for the impact events carrying low incident energies of 10 and 20J. At the impact energies of 35 and 50J the natural outdoor exposures appear to cause appreciable degradation in the impact resistance of the CPVC pipe material. This degradation is noted only for the longer exposure periods of 12 and 18 months.

scholarly journals Effect of Ti(C, N) Particle on the Impact Toughness of B-Microalloyed Steel

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 868 ◽  
Author(s):  
Yu Huang ◽  
Guo-Guang Cheng ◽  
Shi-Jian Li ◽  
Wei-Xing Dai ◽  
You Xie
Keyword(s):  
Impact Toughness ◽  
Microalloyed Steel ◽  
Fracture Initiation ◽  
Sem Analysis ◽  
Number Density ◽  
Size Number ◽  
Microalloying Elements ◽  
The Impact ◽  
Ti Content ◽  
Scanning Electron

Simultaneously improving the toughness and strength of B-microalloyed steel by adding microalloying elements (Nb, V, Ti) has been an extensively usedmethod for researchers. However, coarse Ti(C, N) particle will precipitate during solidification with inappropriate Ti content addition, resulting in poor impact toughness. The effect of the size, number density, and location of Ti(C, N) particle on the impact toughness of B-microalloyed steel with various Ti/N ratios was investigated. Coarse Ti(C, N) particles were investigated to act as the cleavage fracture initiation sites, by using scanning electron microscopy (SEM) analysis. When more coarse Ti(C, N) inclusions were located in ferrite instead of pearlite, the impact toughness of steel with ferrite–pearlite microstructure was lower. Meanwhile, when the size or the number density of Ti(C, N) inclusions was larger, the impact toughness was adversely affected. Normalizing treatment helps to improve the impact property of B-microalloyed steel, owing to the location of Ti(C, N) particles being partly changed from ferrite to pearlite. The formation mechanism of coarse Ti(C, N) particles was calculated by the thermodynamic software Factsage 7.1 and Thermo-Calc. The Ti(C, N) particles formed during the solidification of molten steel, and the N-rich Ti(C, N) phase precipitated first and, then, followed by the C-rich Ti(C, N) phase. Decreasing the Ti and N content is an effective way to inhibit the formation of coarse Ti(C, N) inclusions.

scholarly journals How to Tackle the Relationship between Autoimmune Diseases and Diet: Well Begun Is Half-Done

Nutrients ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 3956
Author(s):  
Camilla Barbero Mazzucca ◽  
Davide Raineri ◽  
Giuseppe Cappellano ◽  
Annalisa Chiocchetti
Keyword(s):  
Immune System ◽  
Dietary Patterns ◽  
Eating Habits ◽  
The Body ◽  
Nutritional Interventions ◽  
Complex Interactions ◽  
Immune Mediated ◽  
Energy Consuming ◽  
The Impact ◽  
Ecological Correlation

Nutrition and immunity are closely related, and the immune system is composed of the most highly energy-consuming cells in the body. Much of the immune system is located within the GI tract, since it must deal with the huge antigenic load introduced with food. Moreover, the incidence of immune-mediated diseases is elevated in Westernized countries, where “transition nutrition” prevails, owing to the shift from traditional dietary patterns towards Westernized patterns. This ecological correlation has fostered increasing attempts to find evidence to support nutritional interventions aimed at managing and reducing the risk of immune-mediated diseases. Recent studies have described the impacts of single nutrients on markers of immune function, but the knowledge currently available is not sufficient to demonstrate the impact of specific dietary patterns on immune-mediated clinical disease endpoints. If nutritional scientists are to conduct quality research, one of many challenges facing them, in studying the complex interactions between the immune system and diet, is to develop improved tools for investigating eating habits in the context of immunomediated diseases.

The U. S.-Canada Free Trade Agreement: Impact on the U. S. Steel Industry

1994 ◽  
Vol 38 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Harold R. Williams ◽  
Thomas J. Botzman
Keyword(s):  
Free Trade ◽  
Multiple Linear Regression Model ◽  
Trade Agreement ◽  
Single Equation ◽  
Steel Mill ◽  
Iron And Steel ◽  
Explanatory Variables ◽  
Income Elasticities ◽  
Price And Income Elasticities ◽  
The Impact

This study empirically estimates the impact of the U. S.-Canada FTA on specific iron and steel exports and imports using quarterly data for the period January 1981 to December 1990. A single equation multiple linear regression model is used to quantify at the industry and industry segment levels the impact of the agreement. The dependent variables are the quantities of major steel products traded between the two nations. The explanatory variables include foreign price adjusted for the exchange rate and tariff rate, domestic price, and the industrial production index. Results include calculation of price and income elasticities, which vary considerably by industry segments. The impact of free trade, as modeled, varies widely from product to product. As such it has important implications not only for government policy and employment but also for the adjustment problems faced by both the large integrated steel mill and the minimill producers.

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