Fracture Toughness Characterization of HSLA Steel Weldments PDF Download

Author: Nick Pussegoda
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: P. L. Mangonon
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 408

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Author: J. F. Sovak
Publisher:
ISBN:
Category :
Languages : en
Pages : 150

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A study was conducted to assess the use of various toughness tests and criteria to predict the fracture behavior of weldments containing a low-toughness heat affected zone. Natural fatigue cracks were initiated and propagated to various sizes in 1-inch A537 Class I steel submerged-arc-welded (SAW) and shielded-metal-arc (SMA) butt-welded Tee joints having various weld reinforcement heights (surface cracked specimens). The most severe service temperature and loading rate of secondary containment shells for LNG ships was duplicated by testing the surface cracked specimens at -60 deg F at loading times of about a second. Fracture mechanics procedures and existing empirical correlations among tests were used to interpret the data. The fatigue crack initiation and propagation behavior observed during preparation of these specimens was consistent with published data. Fatigue crack initiation data were obtained at -60 def F. Elastic plastic behavior was observed in 15 out of 16 tests of the surface cracked weldments. The brittle fracture observed in the one test was analyzed and predicted from the lowest values of all the fracture toughness tests except for the KIc (3 point bend) test. Discussions and recommendations are given for assessing toughness results of weldments having a low-toughness zone 'masked' by adjacent high-toughness regions. (Author).

Author: William S. Pellini
Publisher:
ISBN: 9781581451290
Category : Steel
Languages : en
Pages : 46

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The state of knowledge of fracture-safe design for steels is examined in relation to the requirements for achieving practical solutions to general engineering problems. Analytical procedures evolved from fracture mechanics theory are demonstrated to provide for quantitative interpretations of engineering fracture toughness tests. It is thus possible to couple the procedural simplicity which is inherent to engineering tests with the analytical advantages of fracture mechanics theory. The coupling of these two approaches provides for practical advances in fracture-safe design which cover the totality of general engineering problems and requirements. The Charpy V test is shown to have applicability for use in the described fashion primarily in relation to the strength transition for high strength steels. The combined diagrams should serve the needs of both the materials and design fields. (Author).

Author: E. Lucon
Publisher:
ISBN:
Category : Crack resistance curves
Languages : en
Pages : 14

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The safety and reliability of large-diameter pipelines for the transport of fluid hydrocarbons is being improved by the development of high-strength steels, advanced weld technologies, and strain-based design (SBD) methodologies. In SBD, a limit is imposed on the applied strains rather than the applied stresses. For high-pressure pipelines, SBD requires an assured strength overmatch for the weld metal as compared to the base material, in order to avoid strain localization in the weldment during service. Achieving the required level of strength overmatch, as well as acceptable ductility and low-temperature fracture toughness, is a challenge as the pipe strength increases. Published studies show that low constraint geometries such as single-edge tension [SE(T)] or shallow-notched single-edge bend [SE(B)] specimens represent a better match to the constraint conditions of surface-breaking circumferential cracks in large-diameter pipelines during service (Shen, G., Bouchard, R., Gianetto, J. A., and Tyson, W. R., "Fracture Toughness Evaluation of High Strength Steel Pipe," Proceedings of PVP2008, ASME Pressure Vessel and Piping Division Conference, Chicago, IL, July 27-31, ASME, New York, 2008). However, the SE(T) geometry is not included in any of the most widely used elastic-plastic fracture mechanics (EPFM) test standards. A procedure has been developed for performing and analyzing SE(T) toughness tests using a single-specimen technique that includes formulas for calculating the J-integral and crack-tip opening displacement, as well as for estimating crack size using rotation-corrected elastic unloading compliance. Here, crack-resistance curves and critical toughness values obtained from shallow-crack SE(T) specimens (a0/W ? 0.25) are compared to shallow-crack (a0/W ? 0.25) SE(B) specimens. We believe that the SE(T) methodology is mature enough to be considered for inclusion in future revisions of EPFM standards such as ASTM E1820 and ISO 12135, although additional work is needed to establish validity limits for SE(T) specimens.

Author: Peter P. Puzak
Publisher:
ISBN:
Category : Steel
Languages : en
Pages : 36

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The yield strength range for steels from 180 to 210 ksi is currently covered by four weldable alloys of the following nominal chemical analysis: 18%Ni-8%Co-3%Mo maraging steel, 12%Ni-5%Cr-3%Mo maraging steel, 9%Ni-4%Co-0.20%C quenched and tempered (Q and T) steel, and 10%Ni-8%Co-2%Cr-1%Mo-0.10%C Q and T steel. Broad ranges of fracture resistance have been reported for these materials based on various fracture tests, and this report presents information for material selection and design guidance by providing an analysis of the interactions between the metallurgical and mechanical parameters that contribute to the fracture resistance of plate products. Definitions of the interaction between the metallurgical and the mechanical aspects are developed with the use of the Dynamic Tear (DT) test and the Ratio Analysis Diagram (RAD). (Author).

Author: Stephen M. Graham
Publisher:
ISBN: 9781423527633
Category :
Languages : en
Pages : 92

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Welds in marine structures are typically fabricated such that the yield strength of the weld metal is higher than the base plate (over-matched). Allowing the weld metal yield strength to be less than the base metal (under- matching) can increase productivity and weld metal toughness; however, there is some concern that under-matching increases the crack driving force and decreases the weld metal tearing resistance. This study examined fracture behavior of two HY-100 under-matched welds under dynamic loading. A new test fixture that provided greater control of specimen deflection during impact testing of SE(B) specimens was developed, as was a procedure for applying the Normalization Method to the analysis of dynamic fracture toughness tests. Successful application of Normalization involved using multiple specimens with varying ductile crack growth to establish the correct form for the plasticity function. The accuracy of the measured J(sub Id) was verified by comparing with multi- specimen J(sub Id) values. The results from these tests showed that the proximity of the crack tip to the fusion line had more effect on fracture behavior than mismatch level. Narrower fusion line margins led to lower tearing resistance and a greater propensity for fracture instability.

Author: R. W Judy (Jr)
Publisher:
ISBN: 9781581451399
Category : Aluminum alloys
Languages : en
Pages : 16

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Interpretations of fracture toughness characteristics as measured by various test procedures are presented for structural aluminum alloys. Quantitative definitions of the significance of engineering fracture toughness tests are provided by extension of analytical procedures evolved from fracture mechanics theory. The procedural simplicity of the engineering tests coupled with the analytical capabilities of fracture mechanics theory provides for a significant advancement in fracture-safe design procedures for aluminum alloys covering the full range of yield strength. (Author).

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 29

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In this report two methods of fracture analysis of welds will be emphasized, one addressing fatigue life testing and analysis of notches at welds, and the other addressing the final fracture of the welded component and the fracture toughness tests used to characterize final fracture. These fatigue and fracture methods will be described by referring to recent work from the technical literature and from the U.S. Army Armament Research, Development, and Engineering Center, primarily fracture case study and fracture test method development investigations. A brief general summary will be given of fatigue and fracture methods and concepts that have application to welded structures. Specific fatigue crack initiation tests and analysis methods will be presented, using example results from a welded stainless steel box beam of a cannon carriage. Recent improvements and simplifications in J.integral fracture toughness tests will be described, particularly those related to welds. Fracture toughness measurements for various stainless steel weld metals and heat treatments will also be described. (MM).

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 704

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