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.

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 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.

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.

scholarly journals Analysis of the static and dynamic properties of wear-resistant Hardox 600 steel in the context of its application in working elements

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ł. Konat ◽  
R. Jasiński ◽  
B. Białobrzeska ◽  
Ł. Szczepański
Keyword(s):  
Transition Temperature ◽  
Impact Energy ◽  
Impact Test ◽  
Dynamic Properties ◽  
Charpy Impact ◽  
High Strength ◽  
Charpy Impact Test ◽  
Material Behavior ◽  
Significant Difference ◽  
The Impact

Abstract The article discusses the static and dynamic properties of high-strength, boron-containing Hardox 600 steel that is resistant to abrasive wear, both in its delivery state and after normalization. Since the available published material in the literature does not have any real mechanical indicators of the abovementioned steel, a static tension test was carried out at an ambient temperature. The steel’s tensile strength, yield strength, Young’s modulus, elongation and reduction of area were determined from the test. The Charpy impact test at temperatures of −40 °C, −20 °C, 0 °C, and +20 °C and fractographic analysis were performed to determine the transition temperature of ductility to brittleness. In dynamic load conditions, the assigned values of impact energy do not always truly determine the material behavior. Thus, the aim of the fractography was to provide precision when determining the behavior. A significant difference in the impact energy of the tested steel with respect to its heat treatment and ductile-brittle transition temperature was observed and determined based on the impact test result, as well as the nature of the fracture. On the basis of the determined structural and strength characteristics, an analysis of the possibility of application of Hardox 600 steel on selected elements of working machines was performed.

scholarly journals Impact resistance of steel materials to ballistic ejecta and shelter development using steel deck plates

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Kohei Tateyama ◽  
Shino Naruke ◽  
Hisashi Sasaki ◽  
Shinichi Torigata ◽  
...  
Keyword(s):  
Impact Energy ◽  
Impact Test ◽  
Impact Resistance ◽  
Protective Layer ◽  
High Strength ◽  
Steel Plates ◽  
Corrugated Plates ◽  
Shelter Construction ◽  
The Impact ◽  
Ballistic Ejecta

AbstractThe destruction caused by ballistic ejecta from the phreatic eruptions of Mt. Ontake in 2014 and Mt. Kusatsu-Shirane (Mt. Moto-Shirane) in 2018 in Japan, which resulted in numerous casualties, highlighted the need for better evacuation facilities. In response, some mountain huts were reinforced with aramid fabric to convert them into shelters. However, a number of decisions must be made when working to increase the number of shelters, which depend on the location where they are to be built. In this study, we propose a method of using high-strength steel to reinforce wooden buildings for use as shelters. More specifically, assuming that ballistic ejecta has an impact energy of 9 kJ or more, as in previous studies, we developed a method that utilizes SUS304 and SS400 unprocessed steel plates based on existing impact test data. We found that SUS304 is particularly suitable for use as a reinforcing material because it has excellent impact energy absorption characteristics due to its high ductility as well as excellent corrosion resistance. With the aim of increasing the structural strength of steel shelters, we also conducted an impact test on a shelter fabricated from SS400 deck plates (i.e., steel with improved flexural strength provided by work-hardened trapezoidal corrugated plates). The results show that the shelter could withstand impact with an energy of 13.5 kJ (2.66 kg of simulated ballistic ejecta at 101 m/s on impact). In addition, from the result of the impact test using the roof-simulating structure, it was confirmed the impact absorption energy is further increased when artificial pumice as an additional protective layer is installed on this structure. Observations of the shelter after the impact test show that there is still some allowance for deformation caused by projectile impact, which means that the proposed steel shelter holds promise, not only structurally, but also from the aspects of transportation and assembly. Hence, the usefulness of shelters that use steel was shown experimentally. However, shelter construction should be suitable for the target environment.

scholarly journals The Effect of Crystallinity on the Toughness of Cast Polyamide 6 Rods with Different Diameters

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 293
Author(s):  
Miklós Odrobina ◽  
Tamás Deák ◽  
László Székely ◽  
Tamás Mankovits ◽  
Róbert Zsolt Keresztes ◽  
...  
Keyword(s):  
Impact Strength ◽  
Impact Test ◽  
Charpy Impact ◽  
Polyamide 6 ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Tensile Impact ◽  
Different Diameters ◽  
The Impact ◽  
The Degree Of Crystallinity

The present paper concentrates on the toughness and the degree of crystallinity of the magnesium-catalyzed polyamide 6 rods cast in different diametres, which are commonly used for gear manufacturing. Its toughness cannot be regarded as a constant feature due to the casting technology. The mechanical properties of the semi-finished products are sensitive to the manufactured dimension, e.g., cast diameter, which are investigated by the Charpy impact test and tensile impact test. It is generally accepted that the impact strength and tensile-impact strength correlate with the degree of crystallinity beside many other material’s feature. Crystallinity is evaluated by Differential Scanning Calorimetry. The aim of this study is to determine the relationship between toughness and crystallinity of the magnesium-catalyzed cast PA6 rods with different diameters. For the research cast rods between 40 and 300 mm diameter were selected in seven-dimensional steps. Based on the results, it was found that the toughness depends strongly on the diameter size. Furthermore, it is proved that the crystallinity explains 62.3% of the variation of the Charpy’s impact strengths, while the tensile impact method was not suitable to detect the difference between the test samples.

Mechanical Properties of Vanadium Microalloyed High-Strength ASTM A694 Forgings

2017 ◽  
Author(s):  
K. C. Baker ◽  
R. M. Thompson ◽  
T. C. Gorrell
Keyword(s):  
Chemical Composition ◽  
Oil And Gas ◽  
Charpy Impact ◽  
High Strength ◽  
Oil And Gas Industry ◽  
Heat Treating ◽  
Manganese Steel ◽  
Material Test ◽  
Shear Area ◽  
The Impact

Recent upstream oil and gas industry experience has raised attention to substandard properties with high strength carbon steel forgings manufactured to the requirements of ASTM A694 and MSS-SP-44. As part of an internal investigation into quality of commodity pipeline flanges, three flanges certified as ASTM A694 grade F60 to F70, were purchased off-the-shelf from three different manufacturers for microstructural and mechanical property investigation. All three flanges were supplied with material test certificates indicating acceptable material properties. Tensile and Charpy impact specimens were extracted from various locations and orientations in each flange. All three flanges failed to meet yield strength requirements for the specified grade. The impact energy and shear area values were well below those reported on the material test certificates. The discrepancy between the sacrificial testing results and the material test certificates is attributed to the use of separately forged test blocks for quality testing instead of integral prolongations or a sacrificial production part, which is permitted by ASTM A694 and MSS-SP-44. Further investigation was made into the chemical composition and heat treating practices. The chemical composition can be characterized as high strength, low alloy steel (HSLA) by virtue of 0.05–0.08 wt. pct. vanadium added to a carbon-manganese steel with CE(IIW) ranging from 0.43 to 0.45. Advanced microscopy showed that the morphology of the vanadium precipitates was inadequate as a strengthener and deleterious to Charpy impact properties for the size of the flanges and the heat treatment practices applied.

CVN and DWTT Energy Methods for Determining Fracture Arrest Toughness of High Strength Pipeline Steels

2012 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Nonlinear Models ◽  
High Strength ◽  
Correction Method ◽  
Gas Pipeline ◽  
Pipeline Steels ◽  
Curve Model ◽  
Drop Weight Tear Test ◽  
Viable Approach ◽  
Fracture Arrest ◽  
Arrest Toughness

Battelle two curve model (BTCM) was developed in the 1970s and successfully used for determining arrest toughness for ductile gas transmission pipelines in terms of Charpy vee-notched (CVN) impact energy. Practice has shown that the BTCM is accurate only for pipeline grades up to X65, but not for high strength pipeline grades X70 and above. Different methods to improve the BTCM were proposed over the years. This paper reviews the BTCM and its modified methods in terms of CVN energy or drop weight tear test (DWTT) energy for determining arrest toughness of ductile gas pipeline steels, particularly for high strength pipeline steels X80 and beyond. This includes the often-used Leis correction method, the CSM factor method, Wilkowski DWTT method and others. The CVN and DWTT energy-based methods are evaluated and discussed through the critical analysis and comparison with full-scale experimental data. The objective is to identify reasonable methods to be used for determining the minimum fracture toughness required to arrest a ductile running crack in a modern high strength, high pressure gas pipeline. The results show that available nonlinear models to correlate the standard DWTT and CVN energies are questionable, and the Leis correction method is a viable approach for determining arrest toughness for high strength pipeline steels, but further study is needed for ultra-high pipeline grades. Suggestions for further improving the BTCM are discussed.

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