Toughness Evaluation on Seam Weld HAZ of High Strength UOE Linepipe

2006 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Toyohisa Shinmiya ◽  
Satoshi Igi ◽  
Joe Kondo
Keyword(s):  
Fracture Behavior ◽  
Structural Reliability ◽  
Base Material ◽  
High Strength ◽  
Small Scale ◽  
Seam Welding ◽  
Toughness Evaluation ◽  
Surface Notch ◽  
The Relationship ◽  
Haz Toughness

Heat affected zone (HAZ) along with the weld seam of LSAW has discrete microstructure and usually shows lower toughness than base material. Grain coarsening and formation of M-A constituents governs the HAZ toughness, and a lot of efforts have been made to improve HAZ toughness. However, it is impossible to completely reduce the effect of microstructural change by seam welding. Especially, higher strength or heavy wall linepipes which have richer chemistry tend to have lower HAZ toughness. Therefore, it is important to understand the relationship between microstructural characteristics and toughness of HAZ and fracture behavior of HAZ region in order to ensure the structural reliability of seam welded region. In this paper, fracture behavior of X70 grade heavy wall UOE linepipe was investigated. Wide plate tensile test was conducted with the surface notch introduced on to the coarse grain HAZ, as well as the small scale testing such as Charpy and CTOD test. Fracture mechanics analysis was also carried out to understand the critical condition for brittle fracture of HAZ, and compared with the experimental results.

Development and Properties of Ultra-High Strength UOE Linepipe

2004 ◽  
Author(s):  
Hitoshi Asahi ◽  
Takuya Hara ◽  
Eiji Tsuru ◽  
Hiroshi Morimoto ◽  
Yoshio Terada ◽  
...  
Keyword(s):  
Development Program ◽  
Transportation Cost ◽  
High Strength ◽  
Lower Bainite ◽  
Small Scale ◽  
Long Distance ◽  
Fine Grained ◽  
Girth Welding ◽  
Toughness Evaluation ◽  
The Cost

High-pressure operation through high strength linepipe reduces long distance transportation cost of natural gas. In order to maximize the cost reduction, X120 UOE pipe has been developed. Low C-Mo-B steel with fine-grained lower bainite (LB) microstructure realizes high strength, excellent low temperature toughness and good weldability. The technology was verified in small-scale commercial production or “mini-rolls”. Suitability for use as linepipe was demonstrated through an extensive development program that covers burst test, fracture toughness evaluation, girth welding technology, etc. A demonstration line was successfully constructed using the pipes manufactured in the “mini-rolls”.

A Critical View on the Significance of HAZ Toughness Testing

2004 ◽  
Author(s):  
Andreas Liessem ◽  
Marion Erdelen-Peppler
Keyword(s):  
Structural Reliability ◽  
Weld Seam ◽  
Test Procedure ◽  
Small Scale ◽  
Final Conclusion ◽  
Test Procedures ◽  
Current Test ◽  
Good Shape ◽  
Toughness Testing ◽  
Haz Toughness

Within the heat affected zone (HAZ) along the weld seam of LSAW linepipes discrete microstructural regions of reduced toughness can not be avoided and are commonly designated with the term Local Brittle Zones. The nature of these LBZ has been intensively investigated and the gathered knowledge is exploited in today’s steel technology, plate processing and pipe manufacturing. The HAZ toughness has been improved in general by reducing MA constituents and by austenite grain refinement. Nevertheless local areas of low toughness within the CGHAZ can not be avoided completely. They are statistically distributed in every pipe. Furthermore it seems to be widely accepted that the structural reliability of LSAW linepipe produced and inspected with state-of-the-art technology is not influenced as these areas of low toughness have a limited size and distribution. This has been demonstrated by numerous investigations including small scale (CVN, CTOD), wide plate and burst tests. The essence of these investigations is that the failure behaviour of linepipe containing part wall defects in the HAZ is toughness independent. So far researcher’s world is clear and in good shape. Nevertheless many linepipe specifications tend to stipulate stringent test requirements with regard to acceptance criteria for the HAZ. In the occurrences of test failures a re-test procedure for test lot acceptance is carried out. As a matter of fact the LBZ are present along the weld seam over limited areas in each pipe. Therefore such a re-test procedure is regarded to be inappropriate in terms of quality inspection as it randomly sorts out pipes just by the statistical chance. With regard to HAZ toughness the pipes failed by this test do not differ from those pipes accepted and released for dispatch. As a final conclusion it can be stated that the existing test procedures for the HAZ toughness testing of the main standards and specifications do not reflect the current developments with regard to improved HAZ toughness achieved by the development of optimised steel composition and with regard to the enhanced defect detection probability along with modern NDT inspection methods. An amendment of the current test procedures in this direction is proposed. Therefore proposals are made as start for a common discussion.

HREM interface studies in SiC-whisker-reinforced Al2O3 and Si3N4 ceramics

1988 ◽  
Vol 46 ◽  
pp. 734-735
Author(s):  
W. Braue ◽  
R.W. Carpenter ◽  
D.J. Smith
Keyword(s):  
Analytical Data ◽  
Base Material ◽  
High Strength ◽  
Ceramic Composites ◽  
Good Thermal Stability ◽  
All Ceramic ◽  
Sic Whiskers ◽  
Base Composite ◽  
C 30 ◽  
Si3n4 Ceramics

Whisker and fiber reinforcement has been established as an effective toughening concept for monolithic structural ceramics to overcome limited fracture toughness and brittleness. SiC whiskers in particular combine both high strength and elastic moduli with good thermal stability and are compatible with most oxide and nonoxide matrices. As the major toughening mechanisms - crack branching, deflection and bridging - in SiC whiskenreinforced Al2O3 and Si3N41 are critically dependent on interface properties, a detailed TEM investigation was conducted on whisker/matrix interfaces in these all-ceramic- composites.In this study we present HREM images obtained at 400 kV from β-SiC/α-Al2O3 and β-SiC/β-Si3N4 interfaces, as well as preliminary analytical data. The Al2O3- base composite was hotpressed at 1830 °C/60 MPa in vacuum and the Si3N4-base material at 1725 °C/30 MPa in argon atmosphere, respectively, adding a total of 6 vt.% (Y2O3 + Al2O3) to the latter to promote densification.

Microstructure of resistance spot welding of maraging steels

1990 ◽  
Vol 48 (4) ◽  
pp. 900-901
Author(s):  
I. Neuman ◽  
S.F. Dirnfeld ◽  
I. Minkoff
Keyword(s):  
Maraging Steel ◽  
Spot Welding ◽  
Lath Martensite ◽  
Base Material ◽  
Aging Treatment ◽  
High Strength ◽  
Maraging Steels ◽  
Heat Treated ◽  
Current Cycle ◽  
Welding Processes

Experimental work on the spot welding of Maraging Steels revealed a surprisingly low level of strength - both in the as welded and in aged conditions. This appeared unusual since in the welding of these materials by other welding processes (TIG,MIG) the strength level is almost that of the base material. The maraging steel C250 investigated had the composition: 18wt%Ni, 8wt%Co, 5wt%Mo and additions of Al and Ti. It has a nominal tensile strength of 250 KSI. The heat treated structure of maraging steel is lath martensite the final high strength is reached by aging treatment at 485°C for 3-4 hours. During the aging process precipitation takes place of Ni3Mo and Ni3Ti and an ordered solid solution containing Co is formed.Three types of spot welding cycles were investigated: multi-pulse current cycle, bi-pulse cycle and single pulsle cycle. TIG welded samples were also tested for comparison.The microstructure investigations were carried out by SEM and EDS as well as by fractography. For multicycle spot welded maraging C250 (without aging), the dendrites start from the fusion line towards the nugget centre with an epitaxial growth region of various widths, as seen in Figure 1.

Loading rate effect on fracture behavior of fiber reinforced high strength concrete using a semi-circular bending test

2020 ◽  
Vol 240 ◽  
pp. 117681
Author(s):  
Mehran Aziminezhad ◽  
Sahand Mardi ◽  
Pouria Hajikarimi ◽  
Fereidoon Moghadas Nejad ◽  
Amir H. Gandomi
Keyword(s):  
High Strength Concrete ◽  
Fracture Behavior ◽  
Loading Rate ◽  
High Strength ◽  
Rate Effect ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Strength Concrete

Analysis of fracture behavior of high-strength steels in tension after fire exposure

2021 ◽  
Vol 231 ◽  
pp. 111750
Author(s):  
Wen-Yu Cai ◽  
Jian Jiang ◽  
Yan-Bo Wang ◽  
Guo-Qiang Li
Keyword(s):  
Fracture Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Fire Exposure

scholarly journals Maternal toxoplasmosis and the risk of childhood autism: serological and molecular small-scale studies

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jamila S. Al Malki ◽  
Nahed Ahmed Hussien ◽  
Fuad Al Malki
Keyword(s):  
Neurodevelopmental Disorders ◽  
Repetitive Behavior ◽  
Saudi Arabian ◽  
Childhood Autism ◽  
Small Scale ◽  
Autistic Children ◽  
High Prevalence ◽  
Life Threatening ◽  
The Relationship ◽  
Delayed Language Development

Abstract Background Toxoplasmosis resulting from infection with the Toxoplasma parasite has become an endemic disease worldwide. Recently, a few studies have reported a high prevalence of Toxoplasmosis infections among Saudi Arabian women. This disease could become life threatening for pregnant women and for immunodeficient people. There is evidence that infections during pregnancy, especially in the early stages, are associated with neurodevelopmental disorders. Autism disorder represents one of the most common neurodevelopmental disorders worldwide; it is associated with delayed language development, weak communication interaction, and repetitive behavior. The relationship between prenatal toxoplasmosis and autism in childhood remains unclear. The present study aims to report a link between maternal toxoplasmosis and autistic offspring among Saudi Arabian women. Method Blood samples (36 maternal, 36 from their non-autistic children, and 36 from their autistic children) were collected for serological and molecular evaluation. Results A toxoplasmosis infection was reported for 33.34% of participants using an ELISA assay (5.56% IgG+/IgM+, 11.11% IgG−/IgM+, and 16.67% IgG+/IgM-); however, a nested PCR assay targeting B1 toxoplasmosis specific genes recorded positive tests for 80.56% of the samples. In addition, the present study detected several points of mutation of mtDNA including NADH dehydrogenase (ND1, ND4) and Cyt B genes and the nDNA pyruvate kinase (PK) gene for autistic children infected with toxoplasmosis. Conclusion Considering previous assumptions, we suggest that a maternal toxoplasmosis infection could have a role in the development of childhood autism linked to mtDNA and nDNA impairment.

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