scholarly journals Fatigue Properties of Cruciform and Flange-gusset Joints Using Normal and High Strength Steels

2020 ◽  
Author(s):  
Balázs József Mecséri ◽  
Balázs Kövesdi
Keyword(s):  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Steel Grade ◽  
Fatigue Properties ◽  
Test Results ◽  
Stress Range ◽  
Fatigue Lifetime ◽  
Cruciform Joints ◽  
Normal Strength

The objective of this paper is to investigate and compare the fatigue behavior of Normal Strength Steel (NSS) and High Strength Steel (HSS) welded specimens (cruciform and flange gusset joints). Numerous specimens were tested in the framework of the research project. The experimental S-N curves of the test specimens are determined and analyzed by mathematical statistics to consider the uncertainties and scatter of test results. Statistical analysis of the S-N curves showed that the fatigue behavior of as-welded flange gusset joints is identical in the cases of HSS and NSS specimens, which means that there is no difference in the fatigue lifetime depending on the steel grade. However, the as-welded HSS cruciform joints can be more favorable and their fatigue lifetime is longer than the specimens made from NSS, if the stress range is below 100 MPa. The current study shows that the fatigue behavior of as-welded HSS details depends on the geometry of the investigated specimens and its fatigue lifetime can be larger in the small stress range region than for NSS specimens.

Manufacturing of X100 Pipes for the TAP Project

2006 ◽  
Author(s):  
Hans-Georg Hillenbrand ◽  
Andreas Liessem ◽  
Fabian Grimpe ◽  
Volker Schwinn
Keyword(s):  
Research Work ◽  
High Strength Steels ◽  
Strain Curve ◽  
High Strength ◽  
Steel Grade ◽  
Economic Viability ◽  
Test Results ◽  
Stress Strain Curve ◽  
Line Pipe ◽  
Temperature Ageing

The application of high strength steels like X100 are considered as an economical necessity in order to supply large volumes of gas over long distances in a competitive manner. The development of the grade X100 started more than 10 years ago and has progressed significantly. Therefore the focus of actual development and research work is focused on questions regarding the installation and the service behaviour of such high strength steels. In this context the TAP project has been launched by the ENI group in order to provide answers regarding the economic viability, the technological reliability and the real possibility of constructing high pressure pipelines with this newly developed steel grade. In this paper the manufacturing of line pipe in grade X100 for the TAP project including the two fibre reinforced crack arrestors will be summarized and the production results regarding strength and toughness we presented. Furthermore the analysis of tensile test results regarding the influence of specimen type, anisotropy and the effect of thermal treatment (low temperature ageing) on the stress-strain curve will be discussed.

Frequency Effects on Gigacycle Fatigue Properties of High-Strength Steels

2004 ◽  
Author(s):  
Yoshiyuki Furuya ◽  
Saburo Matsuoka ◽  
Takayuki Abe
Keyword(s):  
Fatigue Test ◽  
Testing Machine ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Test Results ◽  
Frequency Effects ◽  
Fracture Region ◽  
Fish Eye

This report will reveal a series of fatigue test results for high-strength steels at 100 Hz and 20 kHz and discuss frequency effects on gigacycle fatigue properties. The 20 kHz fatigue testing machine is an effective tool to conduct gigacycle fatigue tests in a reasonable term, while frequency effects have to be carefully investigated before applying the machine. The fatigue tests were conducted for two kinds of high-strength steels, that were a low-alloy steel and a spring steel. These fatigue test results showed that the frequency effects were negligible even at 20 kHz in case of fish-eye fracture. The fatigue properties in the fish-eye fracture region showed a good agreement between the 100 Hz and 20 kHz tests. Besides, ODAs (Optically Dark Areas) were also observed on the fracture surface even in 20 kHz tests and no difference was found in the ODA sizes between the 100 Hz and 20 kHz tests. These results meant that the 20 kHz tests could provide us appropriate results at least in the fish-eye fracture region. Therefore, the 20 kHz tests were applicable on the evaluation of gigacycle fatigue properties in high-strength steels.

Development of High Steel Grade Seamless X100 Weldable

2008 ◽  
Author(s):  
Alfonso Izquierdo ◽  
Hector Quintanilla ◽  
Gilles Richard ◽  
Ettore Anelli ◽  
Gianluca Mannucci ◽  
...  
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Limit State ◽  
High Strength Steels ◽  
High Strength ◽  
Steel Grade ◽  
Technological Evolution ◽  
Complex Design ◽  
Exploration And Production ◽  
Girth Welds

The technological evolution in the offshore sector points out a trend towards an increasing use of high strength steels (grade 80ksi and higher), for both pipelines and risers. Pipeline specifications for deepwater offshore fields demand developments in design criteria (i.e. limit state design), welding, installation, and laying technologies. As long as the market goes deeper in offshore exploration and production, the market trend is to use heavier pipes in steel grade X65/X70 and some technological limits from several fronts are faced and more attractive becomes for the market to have a lighter high strength 100ksi seamless steel grade. The joint industrial program (JIP), termed “Seamless 100 ksi weldable” launched by Tenaris in order to address the complex design issues of high strength Q&T seamless pipes for ultra deep water applications has been finalized. The 100ksi steel grade has been achieved in two wall thickness 16 mm and 25 mm. The main results from both phase I devoted to the development and production of seamless pipes with minimum 100ksi and phase II devoted to evaluate the high strength seamless pipe weldability will be addressed in this paper. Main microstructural features promoting the best strength-toughness results obtained from phase I and the results from phase II, where the heat affected zone (HAZ) characterization made using stringent qualifying configuration such as API RP2Z and the promising results after qualifying the girth welds simulating a typical offshore operation and the Engineering Critical Assessment for installation will be addressed. The results from this development are of interest of all oil & gas companies who are facing as an output from the design project analysis the need to have high strength seamless pipes.

scholarly journals Gigacycle Fatigue Properties of Hydrogen Charged High Strength Steels

2013 ◽  
Vol 99 (7) ◽  
pp. 494-501 ◽  
Author(s):  
Hisashi Hirukawa ◽  
Yoshiyuki Furuya
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Fatigue Properties

Fatigue-Corrosion of High Strength Steels in Synthetic Seawater under Cathodic Protection

2020 ◽  
Vol 841 ◽  
pp. 294-299
Author(s):  
Sergio Lorenzi ◽  
Cristian Testa ◽  
Marina Cabrini ◽  
Francesco Carugo ◽  
Luigi Coppola ◽  
...  
Keyword(s):  
Cathodic Protection ◽  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Loading Frequency ◽  
Offshore Pipelines ◽  
Synthetic Seawater ◽  
Steel Grades ◽  
Protection Potential ◽  
Fatigue Corrosion

The paper is aimed to the study of the corrosion-fatigue behavior of high strength steels for offshore pipelines. Tests have been performed in order to study fatigue crack growth in synthetic seawater under cathodic protection. The tests have been carried out on three different steel grades from 65 to 85 ksi with tempered martensite and ferrite-bainite microstructures. The effect of stress intensity factor, cathodic protection potential and cyclic loading frequency is shown.

Study of Fatigue Behavior for Spot Welded Tensile Shear Specimens of Advanced High Strength Steels

2012 ◽  
Vol 83 (10) ◽  
pp. 988-994 ◽  
Author(s):  
Gert Weber ◽  
Stephan Brauser ◽  
Holger Gaul ◽  
Michael Rethmeier
Keyword(s):  
Fatigue Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Shear ◽  
Advanced High Strength Steels ◽  
Spot Welded

Reliability of Burst Limit States for Damaged and Corroded High Strength Pipelines

2006 ◽  
Author(s):  
Marc A. Maes ◽  
Mamdouh M. Salama ◽  
Markus Dann
Keyword(s):  
Limit State ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
Limit States ◽  
Lower Strain ◽  
Margin Of Safety ◽  
Normal Strength ◽  
The Impact

High strength steels (X100 and X120) that are being considered for high pressure gas pipelines differ from conventional steels by exhibiting lower work hardening capacity, lower strain to failure and softening of their HAZ. These differences impact burst limit state and tensile limit state, in addition to crack arrest. In this paper, the impact of the variations in mechanical properties on the reliability of pipe limit states involving ductile burst of damaged or corroded pipe is examined. The paper presents the results of burst limit state analysis using state-of-the-art plastic burst models of strain hardening pipe and considering all the uncertainties that impact the margin of safety of pipes subject to internal pressure. Intact pipes, corroded pipes and externally damaged pipes are considered. A case study comparing the differences between normal strength (X60) pipeline and high strength (X100) pipeline is also presented.

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