Determination of the gross heat input in arc welding

Liskévych, Olga; Scotti, Américo

doi:10.1016/j.jmatprotec.2015.06.005

Cited by 24 publications

(21 citation statements)

References 9 publications

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“…The procedure applied to determine these actual welding thermal cycles is summarized as follows (more details can be found at Mishchenko [20]): [21]) multiplied by a thermal efficiency factor (g t ). However, intrinsic errors and difficulties to measure thermal efficiency have been demonstrated by Liskevych and Scotti [22] and Hurtig et al [23]. For this reason, and considering the use of resultant actual weld cross sections, in this work the heat input-related input parameter used in Rosenthal's equations is replaced by arc energy (q/v); (d) With the input parameters, the heating and cooling times and peak temperature profiles are traced for each desirable condition; (e) In order to facilitate script programming on Gleeble, the thermal cycle generated is discretized in linear stretches, as illustrated in Fig.…”

Section: Thermal Cycle Parameterization and Scriptmentioning

confidence: 99%

Welding thermal stress diagrams as a means of assessing material proneness to residual stresses

Міщенко

Scotti

2020

J Mater Sci

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In this work, the proposal and appraisal of a method to describe in a quantitative manner the phenomenon of thermal stresses formation in welding at different heat-affected zone (HAZ) regions and under different cooling rates, by means of physical simulation, are explained. Under the denomination of welding thermal stress diagrams (WTSD), initially the concept and experimental arrangements needed to use the idea, based on a Gleeble simulator, are revealed. An approach to determine more realistic thermal cycles (peak temperature and heating/cooling rates) is introduced and applied. The method assessment was carried out by using specimens of a HSLA quenchable steel subjected to different cooling rates (covering a wide range of typical welding heat inputs) and peak temperatures (representing regions progressively farther away from the fusion line). The different thermal stress (TS) curves proved the concept based on the justification of the results. In addition, it was physically demonstrated that TS curves are governed mainly by two complex concurrent phenomena, namely contraction under restriction of heated areas and the expansibility of phase transformation. It was concluded that due to this balance, the highest residual stress (RS) does not occur either at slowest cooling rate or at fastest cooling rate. Nevertheless, the highest RS may not occur at the coarse grain zone either. TS progressively drops along the HAZ regions away from critical regions, and even at sub-critical regions there is tensile RS. Complementarily, it was also concluded that WTSD by physical simulation allows one to determine the deformation behaviour of a material as a function of temperature. This information can be used as input or calibration in modelling for thermal stress generation in steels.

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Section: Thermal Cycle Parameterization and Scriptmentioning

confidence: 99%

Welding thermal stress diagrams as a means of assessing material proneness to residual stresses

Міщенко

Scotti

2020

J Mater Sci

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“…Even though being aware of the limitations of calorimetric methods for heat input measurement, as stated by Hurtig et al [11] and Liskevych et al [12], a fully automated cryogenic calorimeter, as described by Liskevych and Scotti [13], was used. Different from that recommended in the latter citation, all comparisons were carried out following just one test condition to economize resources, i.e.…”

Section: Stage 2: Constant × Pulsed Current In Gtaw Supported By Calomentioning

confidence: 99%

Active power measurement in arc welding and its role in heat transfer to the plate

Jorge

Gohrs²,

Scotti

2017

Weld World

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A contemporary paper claimed that a method using the resistance of impedance (active power) for arc power calculation is more accurate than the conventional approach, with consequences on the actual heat transfer to the plate. However, despite the comprehensive reasoning, no heat-related results are shown in this intriguing paper to support the claim. Thus, the aim of this work was to apply the proposed method for determining the weight of active power in the total arc power. A series of weldments was carried out, by using GTAW in constant and pulsed current modes and short-circuiting GMAW with different inductance settings. The effect of the active power on the heat transfers to the plate was assessed by both bead crosssection geometries and calorimetry. The results showed that even a significant fraction of active power of the total power was reached, no changes in bead geometry or heat input were found. A review of the assumptions used in the primal paper showed that an arc is better represented by an ER circuit than by an RLC circuit. As a conclusion, the arc as a reactance-free load presents no component such as nonactive power and the conventional approaches are accurate methods to measure arc power, representing the actual active power.

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“…The long welding time prolongs the period for the formation of aluminum‐rich intermetallic compounds . It was stated that measurable heat input using calorimetric methods corresponds only to absorbed heat by the base material . Since more energy is supplied to the arc parallel with increasing the heat input, the weld bead is enlarged, which results in decreased toughness of welded area .…”

Section: Introductionmentioning

confidence: 99%

Pulsed metall inert gas (MIG) welding and its effects on the microstructure and element distribution of an aluminum matrix reinforced with SiC composite material

Ulukoy

2017

Materialwissenschaft Werkst

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This study aims to demonstrate the effects of pulsed current on the welding pool and fusion zone microstructures of the aluminum 2014 alloy matrix composite material reinforced with 14 and 20 vol% SiC particles. A programmable synergic controlled MIG welding machine with pulsed power supply was used. One hundred Ampere and 120 Ampere pulsed current values were used to determine the effect of heat input on microstructures. A 1 mm diameter SG‐AlSi5 wire was used as filler material. The microstructures were studied using a scanning electron microscope (SEM) with energy dispersive X‐ray (EDX) spectroscopy, and the phase analyses were performed via X‐ray diffraction analyzer (XRD). The study showed that increasing the SiC rate has a greater effect on the formation of Al4C3 phase than increasing the heat input values. Al4C3 formation was not formed as a needle‐like structure.

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Determination of the gross heat input in arc welding

Cited by 24 publications

References 9 publications

Welding thermal stress diagrams as a means of assessing material proneness to residual stresses

Welding thermal stress diagrams as a means of assessing material proneness to residual stresses

Active power measurement in arc welding and its role in heat transfer to the plate

Pulsed metall inert gas (MIG) welding and its effects on the microstructure and element distribution of an aluminum matrix reinforced with SiC composite material

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