Effect of Strength Matching and Strain Hardening Capacity on Fracture
                    Performance of X80 Line Pipe Girth Welded Joint Subjected to Uniaxial Tensile
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Motohashi, Hiroyuki; Hagiwara, Naoto

doi:10.1115/1.2746402

Cited by 13 publications

(3 citation statements)

References 3 publications

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“…Also of the friction stir welded joints, Cho et al [22] and Khodaverdizadeh et al [23] took the strain hardening exponent as a measure to assess the effectiveness of the welding parameters. Motohashi and Hagiwara [24] strain and fracture behavior of a X80 line pipe welded joint. Nielson et al [25] investigated the plastic flow localization in the 6005A aluminum alloy welds and was finally related to the damage development by numerical modelling.…”

Section: Introductionmentioning

confidence: 99%

Effect of microstructure on strain hardening and strength distributions along a Cr–Ni–Mo–V steel welded joint

Zhu

Xuan

2015

Materials & Design (1980-2015)

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Section: Introductionmentioning

confidence: 99%

Effect of microstructure on strain hardening and strength distributions along a Cr–Ni–Mo–V steel welded joint

Zhu

Xuan

2015

Materials & Design (1980-2015)

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“…Therefore, it is evidently necessary to make further investigations on its possible use with crack defects when there are defects located in the HAZ and bond, in order to establish a strain-based design method for pipeline girth welds in which the effect of strength mismatches is taken into consideration. Furthermore, as we have previously reported [21], the crack growth driving force in girth welds is affected by a range of factors in addition to strength matching, including work-hardening capability, HAZ softening and the groove bevel angle and these factors must be taken into consideration.…”

Section: Required Strength Matchingmentioning

confidence: 97%

Study on ductile crack initiation limit from notch root of pipeline girth welded joints with strength mismatch

Motohashi

Yatabe

2012

Welding International

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This study investigated ductile crack initiation limit of pipeline girth welded joints with different strength mismatches. The ductile crack initiation limit for the girth welded joints was evaluated by conducting three-point bending fracture toughness tests and wide plate tensile tests with a surface notch. In addition, effect of heat input on the ductile crack initiation limit of weld metal (WM) was evaluated on the assumption that a welding condition would be varied in the field in the actual pipeline construction. As the results, the equivalent plastic strain at the notch tip for the ductile crack initiation of the threepoint bending tests was consistent with those of the wide plate tests, and the heat input hardly affected the ductile crack initiation limit within the range of this study. This meant that the ductile crack initiation limit of the pipeline girth welded joints with strength mis-match was able to be estimated using the equivalent plastic strain obtained from the three-point bending tests. Based on these results, we proposed a procedure to determine the rational fracture toughness requirements which took into account the difference in the plastic constraint between standard fracture toughness test and pipeline girth welded joints. This procedure was also possible to determine the required strength matching level for a strain-based design for girth welded joint containing surface notch in the centre of the WM in terms of preventing the ductile crack initiation.

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“…One of the new concepts for American Petroleum Institute (API) X100 grade line pipe steels was the strain-based design (SBD) approach [1]. In order to fulfill the increasing demands for the harsh environmental applications, such as the artic and seismic area, the SBD was considered as a key solution for the X100 line pipe steels.…”

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Direct Observation of the Strain Aging Effects Using the in-situ Heating and Straining Stage for TEM

et al. 2015

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One of the new concepts for American Petroleum Institute (API) X100 grade line pipe steels was the strain-based design (SBD) approach [1]. In order to fulfill the increasing demands for the harsh environmental applications, such as the artic and seismic area, the SBD was considered as a key solution for the X100 line pipe steels. Even though the strength could be diminished during the processing or designing, large uniform elongation is the key requirement for those applications. Many researchers have been focused on the alloy design to fabricate line pipe steels meeting both the transport efficiency and the performance by combining with microstructure and mechanical property analysis [2].Full size X100 steel plate and pipe with 32mm thickness were selected and investigated in this study. The pipe shaping was achieved through UOE (U-ing, O-ing, and Expansion) piping process. The plastic deformation history of the surface was different from that of the center during the process. Tensile stress was applied to bottom of the plate along the transverse direction (TD) which corresponds to outer side of the pipe. On the contrary, compressive stress was applied to top of the plate along the TD. Due to this uneven deformation history, from the surface to the center, it was expected that the dislocation density and structure were different through the thickness. Furthermore, the tensile stress along the TD led to compressive stress along the longitudinal direction (LD), resulting in the Bauschinger effect [3]. The UOE process is typically followed by the anti-corrosion coating process, which requires heating the pipe up to 200-250°C. In that temperature range, solute atoms, such as carbon and nitrogen, can be diffused into the dislocation cores [4]. The yield point phenomena were revealed during the following tensile test on LD. Therefore, it is believed that the deformation behavior was determined by the result of the competition between the strain aging and the Bauschinger effect.The average grain size was measured by using scanning electron microscope (SEM). The dislocation structures of the plate and pipe were observed and analyzed with selecting several layers through the thickness by using transmission electron microscope (TEM). To investigate both the strain and the thermal effect on the strain aging behavior of SBD X100 steels, in-situ heating and straining TEM stage was designed and applied to test the steels. Each step of process conditions, such as heating and applying stress, was simulated in the TEM while observing the microstructural change. The strain aging behavior and the Bauschinger effect were directly confirmed by observing dislocation motions.

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Effect of Strength Matching and Strain Hardening Capacity on Fracture Performance of X80 Line Pipe Girth Welded Joint Subjected to Uniaxial Tensile Loading

Cited by 13 publications

References 3 publications

Effect of microstructure on strain hardening and strength distributions along a Cr–Ni–Mo–V steel welded joint

Effect of microstructure on strain hardening and strength distributions along a Cr–Ni–Mo–V steel welded joint

Study on ductile crack initiation limit from notch root of pipeline girth welded joints with strength mismatch

Direct Observation of the Strain Aging Effects Using the in-situ Heating and Straining Stage for TEM

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