Crack Arrest Toughness of Two High Strength Steels (AISI 4140 and AISI 4340)

1982 ◽  
Vol 13 (4) ◽  
pp. 657-664 ◽  
Author(s):  
E. J. Ripling ◽  
J. H. Mulherin ◽  
P. B. Crosley
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
Aisi 4140 ◽  
Arrest Toughness ◽  
Aisi 4340

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.

Dynamic Ductile Tearing in High Strength Pipeline Steels

1996 ◽  
Author(s):  
F. Rivalin ◽  
A. Pineau
Keyword(s):  
Crack Propagation ◽  
High Strength Steels ◽  
High Strength ◽  
Pearlitic Steel ◽  
Crack Arrest ◽  
Full Scale ◽  
Ductile Crack ◽  
Safety Level ◽  
Dynamic Conditions ◽  
Pipe Burst

The study of rapid ductile crack propagation and crack arrest is a central point if one wants to reach a higher safety level in pipelines. Correlations between Charpy tests and full scale burst tests proved to be unsuccessful in predicting pipe burst for recent high strength steels. This paper presents an experiment which allows to test large SENT specimens under dynamic loading, and to characterize steel resistance against rapid ductile crack propagation by a classical energetic parameter, called the crack propagation energy, R, proposed by Turner. The R parameter proved to be characteristic of the rapid crack propagation in the material, for a given specimen and loading configuration. Failure of the specimen under dynamic conditions occurs by shearing fracture which is the same as in a full scale burst test. An example is given for an X65 ferritic-pearlitic steel loaded under static and dynamic conditions. A fracture mode transition is shown following the loading rate. From a metallurgical point of view, shearing fracture occurs by nucleation, growth and coalescence of voids, as for classical ductile fracture.

Impact of Yield to Ultimate Ratio on the Reliability of Burst Limit States

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

In order to reduce arctic construction and transportation costs, high strength steels (> X80) have been advocated for use in high pressure gas pipelines. These steels differ from conventional steels by exhibiting lower work hardening capacity, lower strain to failure and possible softening of their HAZ. These differences can 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 several pipe limit states involving burst 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. The analysis focuses on different design check equations (DCE) which “control” the safe usage of the pipe. In addition, the paper looks at how external or internal damage or corrosion affects the burst capacity differently for medium versus high-strength pipelines steels.

scholarly journals Architecture of high-strength aluminum–matrix composites processed by a novel microcasting technique

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Chenwei Shao ◽  
Shuo Zhao ◽  
Xuegang Wang ◽  
Yankun Zhu ◽  
Zhefeng Zhang ◽  
...  
Keyword(s):  
Yield Strength ◽  
High Performance ◽  
Aluminum Matrix ◽  
High Strength Steels ◽  
High Strength ◽  
Material Design ◽  
Crack Arrest ◽  
Aluminum Matrix Composites ◽  
Cast Aluminum ◽  
The Matrix

AbstractAs important lightweight structural materials, cast aluminum alloys have been largely used in the transportation and aerospace industries. In general, Al–Si-based alloys comprise more than 90% of all castings due to their excellent castability and corrosion resistance. However, even though various reinforcements have been introduced, the strength of these alloys is not that high, which severely limits their use for certain high-performance applications. Here, we report on a new strategy and technology to reinforce Al–Si alloys to increase their yield strength into the ~400–660 MPa range, a level that is 29–113% higher than that of all current cast Al–Si alloys, laboratory or commercial, and comparable to that of many high-strength steels but with ~40% lower density. By introducing continuous Ti–6Al–4V reinforcements into the Al–Si matrix through a novel microcasting process, the yield strength of the resulting alloy can be enhanced to between 4 and 6 times higher than that of the pure Al–Si alloy. The extraordinary reinforcing effect originates from the occurrence of multiscale strengthening mechanisms, including macroscale compound strengthening (the rule of mixtures amended by crack arrest mechanism), mesoscale strain-gradient strengthening, and microscale interface-affected-zone and nanoparticle strengthening. The core principle of our material design is to make all components of the composite fully participate in plastic (compatible) deformation, and thus, continuous reinforcements, instead of discrete reinforced structures (e.g., particles, whiskers, and short fibers), were introduced into the Al–Si alloy. Combined with 3-D printing technology, the present microcasting process can realize strengthening at the designed position by architecting specific reinforcements in the matrix.

Modelling Cleavage Fracture in High Strength Steels and Their Welds

2005 ◽  
Vol 482 ◽  
pp. 171-174 ◽  
Author(s):  
Rodolfo-Martín Rodriguez ◽  
I. Ocaña-Arizcorreta ◽  
A. Martín-Meizoso
Keyword(s):  
Fracture Toughness ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
High Yield ◽  
Matrix Interface ◽  
High Yield Strength ◽  
Weakest Link ◽  
Different Types ◽  
Fracture Nucleation

High strength steels are characterized by their high yield strength, but to guarantee a safe design, a sufficiently large fracture toughness value is also required. In this paper, the fracture toughness of three high strength steels (sy= 460-890 MPa) and their welds has been studied at low temperatures. Experimental results have been used to validate a statistical “weakest link” fracture model. The model takes into account the possibility of fracture nucleation in different types of particles and brittle phases, as well as the crack-arrest factors at the different microstructural barriers (particle-matrix interface and grain boundaries).

Applicability of Existing Models for Predicting Ductile Fracture Arrest in High Pressure Pipelines

2006 ◽  
Author(s):  
John Wolodko ◽  
Mark Stephens
Keyword(s):  
High Pressure ◽  
Ductile Fracture ◽  
High Pressures ◽  
Fracture Propagation ◽  
High Strength Steels ◽  
High Strength ◽  
Full Scale ◽  
Stage Of Development ◽  
Fracture Arrest ◽  
Arrest Toughness

The ductile fracture arrest capability of gas pipelines is seen as one of the most important factors in the future acceptance of new high strength pipeline steels for high pressure applications. It has been acknowledged for some time that the current methods for characterizing and predicting the arrest toughness for ductile fracture propagation in high strength steels are un-conservative. This observation is based on the inability of existing models to predict the required arrest toughness in full-scale ductile fracture propagation tests. While considerable effort is currently being applied to develop more accurate methods for predicting ductile facture arrest, the resulting models are still in a preliminary stage of development and are not immediately amenable for use by the general engineering community. As an interim solution, a number of authors have advocated the empirical adjustment or reformulation of the existing models for use with the newer, high strength pipe grades. While this approach does not address the fundamental issues surrounding the fracture arrest problem, it does provide methods that can be used in the near term for analysis and preliminary design. The desire to use these existing methods, however, is tempered by the uncertainty associated with their applicability in situations involving high pressures and/or high toughness materials. In an attempt to address some of these concerns, a statistical analysis was conducted to assess the accuracy of a number of available fracture arrest models by comparing predictions to actual values determined from full-scale fracture propagation experiments. From the results, correction factors were developed for determining the required toughness levels in high pressure applications that account for the uncertainty in the theoretical prediction methods.

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