A comparison of as-welded and simulated heat affected zone (HAZ) microstructures

Celin, Roman; Burja, Jaka; Kosec, Gorazd

doi:10.17222/mit.2016.006

Cited by 15 publications

(10 citation statements)

References 9 publications

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“…Another issue is the fact that in a real welded joint, the HAZ regions are narrow in relation to the weldment, which makes it difficult to pinpoint the local where the material or component is most likely to fail during its service period. So, usually to assess and elucidate the effect of welding thermal cycles on the mechanical properties of HAZ, simulations of the welding temperature cycles are used as the appropriate approach 75 . However, as shown in this work, it does not mirror the behavior of the welded joint, because multipass welding presents a completely different behavior.…”

Section: Concerns About Safe Welding Proceduresmentioning

confidence: 99%

Investigation into the Impact Toughness of API 5L X80 Steel Weldments and its Relationship with Safe Welding Procedures

et al. 2020

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API 5L X80 steels are widely used in welded pipes in the petroleum industry. However, microstructural changes in the heat affected zone are a concern when welding such pipes due to the potential formation of regions with low toughness. Despite all the research concerning mechanical properties of welded joints, the acceptance criteria for the qualification of welding procedures are still limited. Welded joints do not always guarantee the safe operation of industrial equipment, because the current Standards adopted are not able to evaluate the properties at some critical regions of the welded joint. This work studied the characteristics of a girth welded joint and showed evidences of low toughness at 0.5 mm from the fusion line due to the micro-phases necklacing the prior austenite grain boundaries. As this feature is not considered by the current Standards for approval of welding procedures, this work proposes an alternative approach to improve the safety of welded structures.

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Section: Concerns About Safe Welding Proceduresmentioning

confidence: 99%

Investigation into the Impact Toughness of API 5L X80 Steel Weldments and its Relationship with Safe Welding Procedures

et al. 2020

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“…With such tools and methods, the weldability issue, regarding provision of optimum cooling time form 800 °C to 500 °C, e.g. t, become more feasible [7]- [10]. The problem of extraction of reliable specimen for toughness evaluation is shown on Fig.…”

Section: Fig3 Dependence Of Hardness On Strengthmentioning

confidence: 99%

“…For detailed investigation of HAZ properties and technological (Heat Input, Q, or cooling time, t) influence on the same, it is a common nowadays scientific practice to simulate and further evaluate any zone of interest within HAZ, which is basically determined by its welding thermocycler (s). Number of such studies [7]- [10]- [11]- [12] are performed, where it is shown that the weakest part of HAZ is CG-HAZ, with its peak temperatures around 1300 °C. In addition, grain-refinement effect within finegrained HAZ (FG-HAZ) with thermo-cycle peak temperature around 900 °C, as well as effect of subsequent passes (for mostly used multy-pass welding) on CG-HAZ is of particular importance (e.g.…”

Section: Cyclesmentioning

confidence: 99%

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Properties mismatching and distribution on structural steels welded joints

Hajro

Tasić

2018

Adv.Tech&Mat.

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The paper presents results of combined, conventional and non-conventional, approach for evaluation of mechanical and technological properties of structural steel's welded joints. The selected structural steels are in the range of most common used strength level(s), as well as corresponding various chemical composition concept(s) and processing routes. A short review regarding weldability is presented based on recommendation provided in EN 1011-2, manufacturers recommendation, and own results. However, even it is a well-known fact, mismatching of properties is presented rather to provide sense of its level for particular steel grades. Moreover, the level of under-matching of weakest weld zone (coarse grained heat affected zone), provided by mean of welding thermo-cycle simulation is presented. This is due to the fact that such estimation is not possible with everyday conventional (standardized) testing. The most important design and technological properties of welded joint(s) are considered; e.g. strength, ductility, hardness, microstructure and toughness.

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“…The most suitable way to produce sufficiently large volumes of material exhibiting a homogeneous microstructure of a certain type is the simulation of microstructures [2,[53][54][55]. Several research groups confirmed suitability of simulated material for mechanical tests [2,53,56]. They compared microstructures and hardness of real weld HAZs with simulated HAZ microstructures.…”

Section: Introductionmentioning

confidence: 99%

Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness

Lojen

Vuherer

2020

Metals

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Appropriate post weld heat treatment (PWHT) is usually obligatory when creep resistant steels are welded for thermal power plant components that operate at elevated temperatures for 30-40 years. The influence of different PWHTs on the microstructure, hardness, and impact toughness of simulated heat affected zone (HAZ) subzones was studied. Thereby, coarse grained HAZ, two different fine grained HAZ areas, and intercritical HAZ were subjected to 20 different PWHTs at temperatures 740–800 °C and durations 0.5–8 h. It was found that the most commonly recommended PWHT, of 3 h or less at 760 °C, is insufficient with respect to the hardness and impact toughness of coarse grained HAZ. To obtain a Vickers hardness ≤ 265 HV and impact toughness at least equal to the impact toughness of the base metal (192 J) in the coarse grained HAZ, it took 8 h at 740 °C, 4 h at 760 °C, more than 1 h at 780 °C, and 0.5 h and 800 °C. Even after 8 h at 800 °C, mechanical properties were still within the target range. The most recommendable post weld heat treatments at 780 °C for 1.2–2 h or at 760 °C for 3–4 h were identified. All specimens subjected to these treatments exhibited appropriate hardness, impact toughness, and microstructure.

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A comparison of as-welded and simulated heat affected zone (HAZ) microstructures

Cited by 15 publications

References 9 publications

Investigation into the Impact Toughness of API 5L X80 Steel Weldments and its Relationship with Safe Welding Procedures

Investigation into the Impact Toughness of API 5L X80 Steel Weldments and its Relationship with Safe Welding Procedures

Properties mismatching and distribution on structural steels welded joints

Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness

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