Influence of Weld Oxides on Ductility and Fracture Toughness of Electric Resistance Welded Joint

It is important for the design engineer to realize that scatter and variability of materials properties are inevitable and must be dealt with appropriately. On occasion, data must be subjected to statistical treatments and probabilities determined. The fracture toughness of pipe steel has great effect on the safety of welded pressure pipe. The fracture toughness test of circumferential welded joint was carried out in this paper for X65 pressure pipe steel. The fracture toughness experimental results were analyzed by using computer program developed by ourselves. The distribution of weld fracture toughness of X65 pressure pipe steel which may accord with normal distribution, lognormal distribution or weibull distribution can be determined by calculating the results only one time. The program, which plays an important role in structure reliability analysis, can be used to determine the probability statistic distribution of the mechanical properties. The calculated results indicate that the weld fracture toughness of the X65 pressure pipe steel can either accord with normal distribution, lognormal distribution or weibull distribution, but the optimum fitting distribution of the fracture toughness is weibull distribution.

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Fracture Assessment of Welded Joint With Geometrical Discontinuity Using the Weibull Stress

Volume 7: Operations, Applications, and Components ◽

10.1115/pvp2006-icpvt-11-94047 ◽

2006 ◽

Cited By ~ 1

Author(s):

Satoshi Igi ◽

Takahiro Kubo ◽

Masayoshi Kurihara ◽

Fumiyoshi Minami

Keyword(s):

Fracture Toughness ◽

Brittle Fracture ◽

Welded Joint ◽

Fracture Toughness Test ◽

Geometrical Condition ◽

Stress Criterion ◽

Toughness Test ◽

Fracture Assessment ◽

Geometrical Discontinuity ◽

Weibull Stress

Recently the Weibull stress is used as a fracture driving force parameter in fracture assessment. The Weibull stress is derived from a statistical analysis of local instability of micro cracks leading to brittle fracture initiation. The critical Weibull stress is expected to be a critical parameter independent of the geometrical condition of specimens. Fracture toughness test using 3-point bending and tensile tests of welded joint specimens with geometrical discontinuity were conducted in order to study the applicability of fracture assessment procedure based on Weibull stress criterion. Steel plates prepared for this study had tensile strength of 490 MPa for structural use. Two kinds of welded joint specimens, “one-bead welded joint” and “multi-pass welded joint” were prepared for fracture toughness test by using gas metal are welding. In tensile test specimen, corner flaws were introduced at the geometrical discontinuity part at where stress concentration is existed. Three dimensional elastoplastic finite element analyses were also carried out using the welded joint specimen models in order to calculate the Weibull stress. The critical loads for brittle fracture predicted by the Weibull stress criterion from CTOD test results of one-bead and multi-pass welded joint specimens show fairly good agreement with experimental results of welded joint specimens with geometrical discontinuity.

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Mechanical Properties and Fracture Toughness of Aluminum Vessels by Friction Stir Welding

Fracture Methodologies and Manufacturing Processes ◽

10.1115/pvp2004-2296 ◽

2004 ◽

Author(s):

Masahito Mochizuki ◽

Masao Toyoda ◽

Masayuki Inuzuka ◽

Hidehito Nishida

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Crack Initiation ◽

Base Metal ◽

Welded Joint ◽

Stir Zone ◽

Crack Initiation And Propagation ◽

Friction Stir ◽

Fine Grained ◽

Initiation And Propagation

Mechanical properties and fracture toughness in friction stir welded joint of vessels of structural aluminum alloy type A5083-O are investigated. Welded joint from 25 mm-thick plate is fabricated by one-side one-pass friction stir. Charpy impact energy and critical crack-tip opening displacement (CTOD) in friction stir weld are much higher than those of base metal or heat-affected zone, whereas mechanical properties such as stress-strain curve and Vickers hardness do not have a conspicuous difference. Effects of microstructure on crack initiation and propagation are studied in order to clarify the difference of fracture toughness between stir zone and base metal. Both tensile test and bending test show that the fine-grained microstructure in stir zone induces to increase ductile crack initiation and propagation resistance by analyzing fracture resistance curves and diameter of dimples in fracture surface. It is found that high fracture toughness value in stir zone is affected fine-grained microstructure by friction stirring.

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Fracture toughness of CA6NM alloy, quenched and tempered, and of its welded joint without PWHT

Welding International ◽

10.1080/09507110802543344 ◽

2009 ◽

Vol 23 (3) ◽

pp. 166-172 ◽

Cited By ~ 4

Author(s):

Walter Jesus Paucar Casas ◽

Sérgio Luiz Henke ◽

Nilceu Novicki

Keyword(s):

Fracture Toughness ◽

Welded Joint

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Correlation of microstructure and fracture toughness of advanced 9Cr/CrMoV dissimilarly welded joint

Materials Science and Engineering A ◽

10.1016/j.msea.2015.04.011 ◽

2015 ◽

Vol 638 ◽

pp. 240-250 ◽

Cited By ~ 23

Author(s):

Qian Guo ◽

Fenggui Lu ◽

Xia Liu ◽

Renjie Yang ◽

Haichao Cui ◽

...

Keyword(s):

Fracture Toughness ◽

Welded Joint

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A Non-Destructive Evaluation Method: Measuring the Fixed Strength of Spot Welded Joint Points by Surface Electric Resistivity

ASME 2010 Pressure Vessels and Piping Conference: Volume 5 ◽

10.1115/pvp2010-25235 ◽

2010 ◽

Author(s):

Akira Shimamoto ◽

Keitaro Yamashita ◽

Hirofumi Inoue ◽

Sung-mo Yang ◽

Masahiro Iwata ◽

...

Keyword(s):

Tensile Strength ◽

Spot Welding ◽

Evaluation Method ◽

Welded Joint ◽

Electric Resistivity ◽

Electric Resistance ◽

Non Destructive Evaluation ◽

Nugget Diameter ◽

Zinc Plating ◽

Non Destructive

Destructive tests are generally applied for evaluating fixed strength of spot welding nuggets on zinc plating steel, which is swidely used as the primary automobile structural material. Destructive tests, however, are expensive and time consuming. This paper discusses a non-destructive method for evaluating of welded joints fixed strength by utilizing surface electric resistance. A nugget tester has developed by authors for this purpose. The non-destructive method focuses on surface electric resistance decreasing rate; α, and effect of the corona bond. Nugget diameter is estimated by RQuota calculated from variation of resistance and constant representing the area of the corona bond. Since maximum tensile strength is correlated with the nugget diameter, it is inferred from the estimated nugget diameter.

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Analysis on Fracture Toughness of the L360QS/N08825 Bimetallic Composite Pipe Welded Joint

Advances in Materials Science and Engineering ◽

10.1155/2019/2983506 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13

Author(s):

Bin Wang ◽

Hongxia Lan ◽

Bobo Lei

Keyword(s):

Electron Microscopy ◽

Fracture Toughness ◽

Large Scale ◽

Welded Joint ◽

Fracture Morphology ◽

Dislocation Slip ◽

Crack Tip Opening Displacement ◽

Opening Displacement ◽

Bimetallic Composite ◽

Composite Pipe

The fracture toughness of the weld and heat-affected zone (HAZ) of the L360QS/N08825 composite pipe welded joint was evaluated by a crack tip opening displacement (CTOD) test. The fracture morphology, microstructure, and inclusion near fracture zones were observed by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). The grain size and grain orientation of the crack propagation zone in the weld were investigated by electron back-scattered diffraction (EBSD). The results revealed that the average CTOD values of the weld and HAZ samples were relatively high, and a greater dispersion of CTOD values of the HAZ samples is due to the pop-in phenomenon in the P–V curve. The fracture surfaces of the weld and HAZ samples showed the characteristics of ductile fracture to a certain extent, whereas the fracture of the CTOD sample with the pop-in phenomenon exhibited a quasicleavage feature. High-density dislocation and a large number of inclusions were observed in the near fracture zone of the weld and HAZ samples. The stress concentration, caused by hindering the dislocation slip, was the main reason for microcrack formation. The existence of large-size grains and large-scale small-angle grain boundary in the weld implies that the cracks propagate toward the weld.

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